PORTABLE STAGE EQUIPMENT.
The general rule is that all wires in theaters must be in conduit or
armored cable. Metal molding is not considered suitable for the stage
side of the theater. There are, however, stage requirements which make
the use of some sort of flexible and portable connection necessary and
for such purposes stage cables are allowed. All wiring that can be
permanently fastened to battens or fastened in other ways; or that is
run inside of posts or statuary, must be in conduit or armored cable.
The National Electrical Code Rules are quoted in this chapter wherever
they apply and should be followed, not only because these rules outline
the best practice but because, throughout the country, inspections will
generally be governed by these requirements. Even where the local rules
vary somewhat from these rules, it will be found that all apparatus
constructed according to them will be favored to a considerable extent.
_Anvil Sparks._--These are sometimes produced by arranging the anvil as
one pole of a circuit and the hammer as the other. When the hammer
leaves the anvil, the spark occurs. A resistance must always be inserted
in the circuit if a light or power circuit is employed. One of the most
successful methods of producing anvil sparks is shown in Figure 180.
When the hammer strikes the anvil the spring follows and strikes the
head of the hammer; and when it rebounds the spark occurs. If it is not
desired to use a power circuit the spark may be obtained from batteries
by the use of a spark coil. Sparks in dueling scenes may be produced in
much the same manner.
In some cities the inspection laws require all arcs or sparks, used on
the stage, to be enclosed. So far as the authors are aware no really
satisfactory method of enclosing anvil sparks has ever been made up. If
such an enclosure is to be constructed it must be borne in mind that it
must not spoil the illusion nor mar the tone in case the anvil is tuned
for use in singing acts. A special combination of metals is on sale at
stage-supply dealers by which sparks can be produced without the use of
current.
[Illustration: FIGURE 180.]
_Arc Lamps._--In Figure 181, there is shown an open or flood lamp, also
known as the “Olivet”. This style of lamp is used on the stage only for
general illumination. As the light from this lamp spreads in all
directions it must be brought close to the part to be illuminated and
this usually brings it close to the scenery.
All portable stage lamps are hand feed and require close attention on
the part of operators. While traveling it sometimes occurs that only
high voltage such as 500 or 600 volts is available and in such a case a
suitable number of lamps must be connected in series. Hand-feed arc
lamps are difficult to start under such circumstances and the following
method is often resorted to: Place the carbons of all the lamps
connected in series the proper distance apart and connect a small fuse
across each gap. When the current is turned on it will melt the fuses
and establish the arc.
[Illustration: FIGURE 181.]
[Illustration: FIGURE 182.]
In Figure 182 we have an illustration of what is known as the _spot_ or
_lens lamp_. This style of lamp is used on the stage, on bridges, or “in
front” (in front being the term by which the balcony or galleries are
designated in this case). In the figure a “Sciopticon” attachment is
shown which is removable. Even very unpretentious shows carry at least
one spot lamp and the largest shows often carry 30 or 40 open and spot
lamps. Arc lamps are often imitated by an incandescent lamp placed
within a suitable globe with the hood made up in the shape of an arc
lamp.
[Illustration: FIGURE 183.]
Figure 183 is a cut of a stereopticon outfit. Dissolving views require
at least two lamps and sometimes three, the third being for the purpose
of providing a frame for the views or adding an extra effect, such as
falling snow. Two lamps at least are always in use at the same time and
it is necessary to provide cables of sufficient carrying capacity for
two or three lamps, as the case may be.
_The National Electrical Code Rules for Arc Lamps to be Used on the
Stage._
Must be constructed entirely of metal except where the use of approved
insulating material is necessary.
Must be substantially constructed, and so designed as to provide for
proper ventilation, and to prevent sparks being emitted from lamps when
same are in operation; and mica must be used for frame insulation.
Front opening must be provided with self-closing hinged door frame, in
which wire gauze or glass must be inserted, except in the case of lens
lamps, where the front may be stationary, and a solid door be provided
on back or side.
Must be so constructed that neither carbons nor live parts will be
brought into contact with metal of hood during operation, and arc-lamp
frames and standards must be so installed and protected as to prevent
the liability of their being grounded.
Switch on standard must be so constructed that accidental contact with
any live portion of same will be impossible.
All stranded connections in lamp and at switch and rheostat must be
provided with approved lugs.
Rheostats must be plainly marked with their rated capacity in volts and
amperes, and, if mounted on a standard, must be raised to a height of at
least three inches above the floor. Resistance must be enclosed in a
substantial and properly ventilated metal case which affords a clearance
of at least one inch between the case and the resistance element.
A competent operator must be in charge of each arc lamp, except that one
operator may have charge of two lamps, when they are not more than ten
feet apart and are so located that he can properly watch and care for
both lamps.
Each lamp should be provided with its own fuses and switch.
_Baby Spot Lamp._--This is the name given to a small lens lamp in which
an incandescent lamp is used instead of an arc lamp. Such a lamp cannot
be used for projection very well but is well suited to illuminate parts
of an act that do not require very bright illumination. It is sometimes
used to take the place of proscenium side lights. In one well-known
production twelve such lamps were used upon scaffolding directly above
the proscenium opening. The incandescent lamp is movable for the purpose
of focusing; but it not being a “point source”, no such accurate
focusing is possible as with arc lamps.
_Batteries._--Both primary and secondary, or storage, batteries are
extensively used upon the stage. Small dry cells are often used to ring
bells or light miniature lamps in the hair or clothes of the chorus. The
electromotive force of a cell is independent of the size and depends
only upon the materials used; but the current which a battery can
deliver varies directly with its size. If we wish to increase the
voltage we must connect several cells in series, as indicated in Figure
184; if we have sufficient voltage but lack current we must connect, as
in Figure 185. As a general rule, in any circuit, we must connect the
battery so that its resistances shall most nearly equal the resistance
of the device which it feeds. This means that if the resistance of the
device is greater than that of the battery we must connect our battery
in series; if it is less we must connect the cells in multiple, as
indicated by Figure 185.
When connecting cells in multiple those of the same kind should always
be selected. Any cell whose electromotive force is not fully equal to
the others will absorb energy and be charged by the others. The
resistance of small cells is high and it is best, where size is not
objectionable, to use large cells. Storage, or secondary batteries, have
low resistance and are capable of delivering very strong currents, even
though the voltage be low. The heat is proportional to the square of the
current and a certain amperage, with two volts back of it, will produce
just as much heat in given resistance as the same amperage with several
hundred volts. The sparking in case of a broken circuit or a fuse
blowing would, however, be hardly noticeable with the low voltage.
[Illustration: FIGURE 184.]
[Illustration: FIGURE 185.]
No definite rule is given concerning the fusing of low-voltage storage
batteries, but it is good practice to insert a double-pole fuse in each
branch circuit; the fuse to be small enough to protect the smallest wire
fed through it. The capacity of storage batteries is usually given in
“ampere hours”. A 60-ampere-hour battery, for instance, can deliver
three amperes for twenty hours or ten amperes for six hours. With every
battery there is, however, a certain maximum rate of discharge which
should not be exceeded. The battery should not be allowed to run down
too low and should be kept well charged. It is best to follow the
instructions which the makers send out with them.
_Bells._--Electric bells are used on the stage for many purposes.
Sometimes they are used as musical instruments, the gongs being properly
tuned; at other times they are provided to ring in connection with
certain acts; and they are also used for the purpose of signaling. When
signals are to be given, which the audience must not hear, it is better
to provide buzzers.
[Illustration: FIGURE 186.]
Bells can be arranged to operate from power circuits by placing an
incandescent lamp, or some other suitable resistance, in series with
them; but it is not advisable to do so. It is not safe from a
fire-hazard point of view, and also not very practical, since in many
places alternating current only can be had and the ordinary bell does
not operate well with it. Batteries should always be used for bells and
other low-voltage devices.
Where it is desired to operate a number of bells together, they may be
arranged in series, as shown in Figure 186, in which the vibrator of one
bell is cut out of circuit so that the vibrations of this bell are
governed by those of the other. Sets of bells properly tuned are often
scattered about and controlled from a keyboard. There are usually
eighteen bells in such a set.
_Blinding Lights._--In certain acts it is necessary for the actor to
work part of the time unseen by the audience. This may easily be
arranged for by the use of a number of bright lights placed between him
and the audience. These lights, when burning, blind the audience so that
they cannot see beyond them. The lamps must be placed in reflectors
which throw all light toward the audience. They are arranged either upon
the floor of the stage or around cabinets or other devices. The blinding
effect depends upon the contrast between the front and the rear of the
lamps. Lights should be very bright but the quantity of light must not
be sufficient to cause reflected light from the front to illuminate the
back of the stage. Where emergency lights are kept burning during the
performance it is quite difficult to carry out the blinding effect for
any considerable length of time.
_Brackets._--Brackets are made up in any of the three ways shown in
Figure 187. If the stem is large enough to admit the cable, which should
be used to the pin-plug connector, no splice of any kind will be
necessary. If the bracket stem is too small for this, fixture wire must
be used and a connection from it to the cable must be made. If this is
made, as at the extreme right, the back of the canopy must be enclosed
in substantial metal. On no account should fixture wire be allowed to
extend outside of the stem. The bracket must have some provision by
which it can be made to hold its proper position when in place.
Sometimes hooks are provided for this purpose and at other times it is
held in place by screws in the scenery, as suggested by the back of the
canopy shown at _A_.
_National Electrical Code Rule for Lights on Scenery._
Where brackets are used they must be wired entirely on the inside;
fixture stem must come through to the back of the scenery and end of
stem be properly bushed.
[Illustration: FIGURE 187.]
_Bunch Lights._--Bunch lights are made up according to the plans shown
in Figure 188. They are used only on the stage. No very brilliant
illumination can be obtained from them. In one well-known production a
bunch light containing one hundred 32 c.-p. lamps was used without
obtaining the result desired. The light cannot be concentrated as can
that from arc lamps. Bunch lights, however, have the advantage of not
requiring so much attention as arc lamps and can often be used on a
shallow stage where arc lamps would be out of place. Bunch lights are
sometimes made double, two on one stand; two colors can thus be used at
the same time and certain color changes facilitated. Color effects or
changes in colors are brought about by inserting colored gelatine slides
in front of the lights.
_National Electrical Code Rules for Bunch Lights._
Must be substantially constructed of metal and must not contain any
exposed wiring.
[Illustration: FIGURE 188.]
The cable, feeding same, must be bushed in an approved manner where
passing through the metal, and must be properly secured to prevent any
mechanical strain on the connection.
_Chandeliers._--The rule which requires all wiring about brackets to be
enclosed, naturally would apply here also. In connection with chain
fixtures, which are at present very popular, this requirement is
generally overlooked if good reinforced cord is used. Ordinary fixture
wire or flexible cord should not be used. The weakest part of a chain
fixture is indicated in Figure 189 by the arrow. The opening at this
place is, as a rule, too small and not well reamed out. Fixtures used on
the road are constantly giving way at this point. The opening should be
large enough to pass reinforced cord and should be well reamed out. If
the opening cannot be made large enough to give the wire a little free
movement, it is advisable to wrap tape around the wire and the metal in
such a way as to prevent all motion of the wire at this point. The same
observations also apply to the other end where the cord enters the
socket.
[Illustration: FIGURE 189.]
[Illustration: FIGURE 190.]
[Illustration: FIGURE 191.]
Another frequent source of trouble with chandeliers is found at the end
of the stem where connection is made to the cable which feeds the
fixture. See Figure 190. Very often fixture wire is brought out here,
but this will soon break. The stage cable, or reinforced cord, should be
run down to the bottom of the fixture and connections there made to the
wires leading to the various arms. There are many fixture hooks made up
after the manner shown in Figure 191 which have a small opening for the
wire at the point indicated by the arrow. This opening is always too
small and in such a case it is best to arrange a tee as shown. A
chandelier must always be hung in such a manner as to avoid strain
coming on the electrical conductors.
[Illustration: FIGURE 192.]
_Colors._--Where a certain color is wanted, during the whole show, from
a certain light source, the incandescent lamps themselves may be
colored. Prepared colors for this purpose are on the market and it is
best to use them. Where the colors in a scene change rapidly there must
be some colored material available which can be quickly interposed
between the light and the scene. The manner in which this is done for
bunch lights is indicated in Figure 188. The same method is also used in
connection with open-arc lamps, but for spot lights there is another
method, shown in Figure 192. This is a so-called color wheel and the
colors can be changed by simply revolving the wheel until the proper
color is in front of the lens. An automatic color wheel is on the market
which allows the operator to control colors at a distance by means of an
electric circuit and magnet. This device cannot be used with flood lamps
and has the further disadvantage of casting unavoidable shadows during
the change of colors. Where detachable color holders are used, it is
possible to change from one color to another by almost imperceptible
degrees by holding the frame in the hand and bringing it gradually from
a distance to the front of the lamp. In this manner the shadows cast by
the frame can be avoided and the color brought very gradually into the
scene.
[Illustration: FIGURE 193.]
_Dimmer Box._--The dimmer box, as the name implies is a box which
contains the resistances required for dimming lights used on the stage.
It comes into service only with the more pretentious shows which carry
foot-lights or border-lights. A typical wiring diagram is shown in
Figure 193. This diagram supposes that not more than three colors are
used. A small candle power incandescent lamp should always be installed
in the box so that the operator may see what is necessary in dark
scenes. This lamp should have its own fuse protection. This is a point
very often overlooked by operators. The box is usually made of wood and
lined with metal. It should be deep and nearly square, so as to occupy a
minimum of space. If a shallow box is used, it will be necessary to
place the switches in a separate compartment from the fuses, so that the
latter may be always enclosed, even while the dimmers and fuses are
being operated.
[Illustration: FIGURE 194.]
Provisions should be made for the cables to lead out through suitable
bushings at the side instead of over the top of the box as is so often
done. In some dimmer boxes the slip connectors are fitted into the side
of a box so that the male end may be inserted from outside. This makes
it unnecessary to bush the cables through the box.
_Electric Sign Imitations._--These are used mostly in representations of
city night scenes. A flasher sign can be imitated by cutting small round
holes in the curtain to outline the reading matter on the sign. Behind
these holes a moon box is placed, the lamps in it being on a flasher or
controlled by “skeedoodle” sockets, thus giving the effect of an
electric sign on a flasher. In case the effect of a steady burning sign
is wanted the flasher is omitted.
Electric signs imitating falling water have in turn been imitated
according to the plan outlined in Figure 194. On the side nearest the
audience is the curtain _A_, upon which the sign is painted and in which
there are a number of holes representing the electric lamps in the
original sign; behind this curtain is a grating _B_, also full of holes;
and behind this revolves a spiral _C_, so arranged as to obstruct
intermittently the light which is behind it. The object is to imitate,
as nearly as possible, the action of the lights in the original sign.
_Electric Stage Effects._--A large number of stage effects can be
produced by properly painted mica discs which are caused to move in
front of the lens of a spot light arranged for the purpose. A view of
such a contrivance is given in Figure 182 and is known as the
“Sciopticon”. The effects are changed by clockwork which is adjustable
as to speed. The device is arranged to slip in front of the lenses and
can be attached in a moment.
A list of some of the effects obtainable is given below:
Avalanche
Climbing monkeys
Cyclone with flying objects
Falling leaves
Fireworks
Flame
Flowing water
Flying birds
Lightning
Moving clouds
Niagara Falls
Ocean waves
Rainbow
Rain
Rising fire and smoke
Rolling lava
Sand storm
Snow storm
Swimming fish
Twinkling stars
Volcano
Water falls
The above list is given to illustrate the possibilities of this method
of producing effects. They are, however, rather expensive and some of
them require several machines to be in operation at the same time.
_Explosions._--Nearly all explosions are set off by the melting of a
fuse through an electrical short circuit. The explosive powder is placed
above, encloses the fuse, and is ignited when the fuse blows.
[Illustration: FIGURE 195.]
Such explosions are often forbidden by inspectors but there is no danger
from them if the powder, etc., is enclosed in a suitable wire mesh open
on all sides. This will not interfere with the explosion and will
prevent the flame, which lasts but an instant, from coming in contact
with scenery or people. Where such explosions are used they are
generally the most important part of the act, and every possible
precaution must be taken to avoid the chance of failure. They are,
therefore, often arranged on two circuits with a throw-over switch so
that in case one fuse fails the circuit can be immediately closed on the
other. See Figure 195. It requires some time to throw-over a switch, and
in order to make doubly sure that the fuse will blow at the right time,
two fuses and two separate wires may be used and connected at the same
time by a simple double-pole switch. The latter arrangement has the
disadvantage that one of the wires might be broken, or the contacts bad,
without the defect ever being noticed until the other wire also fails
and the explosion misses entirely.
It is best to use the throw-over switch and to use the wires for the
first connection in alternation so that a defect may be noticed at once.
If the same wire were used each time the throw-over switch would be open
to the same objection as the double-pole switch. In selecting fuses for
this work it must be borne in mind that the powder which is placed over
the fuse has a certain cooling and conducting effect, and that often,
therefore, a fuse which would readily blow if in the open would not blow
if covered with metallic powder.
_Face-O-Graph._--This is an arrangement of two powerful arc lamps with
the necessary lenses and objective by which the face of an actor can be
projected upon a screen. This effect is very trying to the face and eyes
of the actor. The face must be brought very close to the arc lamps and
must be held upside down during the performance. From forty to fifty
amperes are used in each arc lamp. The optical principle is explained in
another chapter.
_Festoons._--Festoons should be made up as shown in Figure 196.
Weatherproof sockets are generally used because the common brass shell
sockets have too many parts that are liable to work loose on account of
the constant handling the festoons are subjected to with traveling
productions. The use of porcelain sockets, however, should be avoided;
mica sockets seem to be generally preferred. The soldering also should
be carefully done and only at the end, as indicated by the arrow in the
cut. The branch wires are often taped to the main cable as indicated,
but often also, circular loom is slipped over the cable in such a manner
that the branch wires are supported by it. Short lengths of loom must be
slipped on the cable before the tapes are made. A really well made
festoon will last a long time and give very little trouble; while a
poorly made one will cause much annoyance and much unfavorable comment
from inspectors. Most of the festoon troubles are due to poor support of
the branch wires. A single festoon does not often carry more than ten or
twelve lights and usually not more than six or eight.
[Illustration: FIGURE 196.]
A certain style of shade is very much in vogue in connection with
festoon lamps and this shade makes the use of lamp guards impossible. If
the shade is made of gelatine there will be but little need for the
guard, but celluloid shades should not be allowed. All combustible
material that is to come near the lamp or the socket should be
fireproofed.
_The National Electrical Code Rule for String or Festooned Lights._
Wiring of same must be of approved type; joints to be properly made,
soldered, and taped, and staggered where practicable. Where lamps are
used in lanterns or similar devices, approved guards must be employed.
_Fire Dance._--This effect is generally illuminated from below the
stage, the light being thrown upward through glass. Special arc lamps,
equipped with powerful reflectors, are often used and generally several
of them are required to produce the proper effect. If spot lamps are to
be used they should not be turned upward but instead reflectors placed
at an angle of forty-five degrees, should be provided to throw the light
upward. See Figure 197. If a spot lamp is turned upward, the heat of the
arc rising will be great enough to make condenser breakage a very
serious problem. It is also difficult to keep a horizontal arc working
properly.
[Illustration: FIGURE 197.]
_Fireflies._--The “fireflies” are miniature incandescent lamps strung
about among the scenery and on the clothing or in the hair of
performers. No attempt should be made to operate these from any other
source than a low-voltage, low-amperage battery. It is best to subdivide
them as much as possible to avoid short circuits. A short circuit on one
lamp would put out a group of one hundred as quickly as it would ten.
Such lamps are often arranged on a keyboard by which single lamps or
small groups may be lighted intermittently, thus giving the effect of
fireflies flitting about.
_Fireplaces._--The commonest and best fireplace is made up of a few
lights arranged in regular strip fashion, the strip being placed in a
practical fireplace filled with coal or large pieces of glass, such as
broken pieces of lenses. For a very simple effect, red colored globes
are used. The effect can be enhanced by using lamps of amber, red, and
white and connecting each lamp to a dimmer which can be worked off the
stage. This is capable of producing a flaming effect. A further
enhancement of the effect is sometimes produced by placing colored
asbestos about the lights. This or other suitable material can be made
to represent glowing ashes very nicely. Very often the illumination of
the fireplace is by means of colored globes strung about among the logs.
For this purpose they must be equipped with strong guards and wired with
stage cable. Actual gas flames are also often mixed in with the electric
illumination. In a mechanical way the effect of flame is often imitated
by colored cloth so arranged that a small fan motor placed beneath it
can blow it upward.
In a certain well-known production, an imitation of the crater of a
volcano is made by arranging a number of fan motors under a large piece
of silk which rests upon a frame and revolves over the motors. Parts of
this silk are provided with pockets and are loose so that they may be
blown upward to represent flame while the major portion only undulates,
representing a sea of molten lava. Strips with red lights are used to
intensify the effect.
A small motor operating a suitable ratchet has been used to imitate the
sounds of wood crackling in the fire. “Chemical smoke” is also often
used to enhance the effect. This can be purchased of supply houses.
_Flat Irons._--See “Heaters”.
_Flowers._--On the vaudeville stage, electrically lighted flowers are
sometimes used. These are often wired by simply running fixture wire or
flexible cord along a wire stem and fastening a small socket to it.
Flowers lighted in this manner, however, will not be allowed in theaters
where there is inspection. A better method is shown in Figure 198.
Armored cord is used for the stem and a miniature socket is placed at
the end. All splices are within the junction box which supports the
stems. Instead of the armored cord ordinary fixture tubing may be used.
Baskets of flowers and small bouquets are generally lighted from
batteries.
[Illustration: FIGURE 198.]
_Fountains._--The illumination for electrically lighted fountains is
sometimes obtained from incandescent lamps, but no very showy effects
can be produced with them. Where they are used in a manner which
subjects them to moisture they must be wired in waterproof conduit and
fittings and the lamps must be covered by a watertight globe. For
brilliant effects arc-lamp illumination is necessary and the arc must of
course be below the water. As arc lamps when tilted upward break
condensers very rapidly, the light is usually reflected upward by means
of mirrors set as indicated in Figure 197.
_Fuses._--There is no part of the electrical equipment of a traveling
production so much abused as the fuse. It is provided primarily for the
protection of apparatus and should never be of greater capacity than is
needed to carry the load put upon it. There is nothing whatever gained
by the use of larger fuses. If the load is not in excess of six amperes,
a six ampere fuse will carry it as readily as a twenty ampere fuse. If a
short circuit occurs the twenty ampere fuse will blow as readily as the
six ampere fuse and, in addition, will cause destruction of a socket or
whatever may be the cause of the trouble as well as an increased fire
hazard. Notwithstanding the above, it is a rare exception when one finds
the circuits of a traveling outfit properly fused. For this there are
two reasons. One is that, owing to frequent handling and moving, fuses
work loose; and thus, to the natural heat produced by the load, there is
added a certain amount of heat produced in the poor contacts. Trouble of
such a nature can be lessened by the use of larger fuses, but only to a
very small extent. It is far better to go over one’s fuses two or three
times a week and tighten the screws and contacts to avoid this trouble
than to use over-large fuses.
Another reason for the overfusing, of plugging boxes especially, is
found in the fact that arc and incandescent plugs are interchangeable.
If, therefore, each circuit is fused at thirty amperes one need not
worry about which pocket an arc lamp is connected to. This practice is,
however, very bad, a table lamp, for instance, with a thirty-ampere fuse
behind it would be likely to cause flash and smoke enough to alarm an
audience. Some provisions should be made so that one can easily
distinguish between arc and incandescent pockets or divisions in
plugging boxes. The main requisite which determines the style of fuse to
be installed for stage effects is that of quick renewal in case of
blow-out.
[Illustration: FIGURE 199.]
_Gas Globes._--Electric light is so convenient on the stage that even
gas light is imitated by it. In one production in which it was desirable
to show the front of a theater illuminated by gas, the gas globes were
made up of cloth cut as shown in Figure 199. Behind each imitation globe
a small incandescent lamp was arranged.
_Glass Shades._--An imitation of these for small desk or table lamps is
often made by placing a strip of colored gelatine between two layers of
wire mesh. The wire screen keeps the gelatine straight and the whole is
more serviceable than glass and less liable to break.
_Heaters._--Under this head come flatirons and water heaters. Flatirons
are carried by many actors who cause much trouble by connecting them to
lighting circuits. In many places the house electrician prevents their
use by fusing his lighting circuits so low that the addition of a
flatiron immediately blows the fuse. If used at all, the flatirons
should be of the smaller kind. Small heaters are also extensively used
upon the stage.
_National Electrical Code Rule for Electric Heaters._
It is often desirable to connect in multiple with the heaters and
between the heater and the switch controlling the same, an incandescent
lamp of low-candle power, as this shows at a glance whether or not the
switch is open, and tends to prevent its being left closed through
oversight.
Must be protected by a cut-out and controlled by indicating switches.
Switches must be double-pole except when the device controlled does not
require more than 660 watts of energy.
Must never be concealed; but must at all times be in plain sight.
Special permission may be given in writing, by the Inspection Department
having jurisdiction, for departure from this rule.
Flexible conductors for smoothing irons and sadirons and for all devices
requiring over 250 watts must have an approved insulation and covering.
For portable heating devices the flexible conductors must be connected
to an approved plug device, so arranged that the plug will pull out and
open the circuit in case any abnormal strain is put upon the flexible
conductor. This device may be stationary, or it may be placed in the
cord itself. The cable or cord must be attached to the heating
apparatus in such a manner that it will be protected from kinking,
chafing, or like injury at or near the point of connection.
Smoothing irons, sadirons, and other heating appliances that are
intended to be applied to inflammable articles, such as clothing, must
conform to the above rules so far as they apply. They must also be
provided with an approved stand, on which they should be placed when not
in use.
Stationary electric heating apparatus, such as radiators, ranges, plate
warmers, etc., must be placed in a safe location, isolated from
inflammable materials, and be treated as sources of heat. Devices of
this description will often require a suitable heat-resisting material
placed between the device and its surroundings. Such protection may best
be secured by installing two or more plates of tin or sheet steel with a
one-inch air space between or by alternate layers of sheet steel and
asbestos with a similar air space.
Must each be provided with name-plate, giving the maker’s name and the
normal capacity in volts and amperes.
_Lighthouse Effect._--To increase the effect of a lighthouse painted
upon the scenery, a strip of suitable length with one light at each end
is provided. The strip circuit contains a flasher so that both lights
are turned on and off at regular intervals. One lamp must be behind the
head of the lighthouse, the other where the reflection of the upper
light would appear in the water.
_Lightning._--The standard method of producing lightning effects upon
the stage is by means of the device shown in Figure 200. A magnet and
the arc-striking carbons are arranged in series and take current through
a resistance. Normally the carbons are in contact and when the switch is
closed the current passes through the magnet and carbons. The current
energizes the magnet and causes the upper carbon to separate from the
lower, thus striking the arc. The arrangement must be such that the arc
is immediately broken, thus de-energizing the magnet; this allows the
movable carbon to close the circuit again, thus repeating the operation.
This device if uninterrupted will give a rapid succession of lightning
effects and it may be suspended in the wings as it is entirely
automatic. At the right of Figure 200 is shown another lightning striker
which is operated by hand.
[Illustration: FIGURE 200.]
Where it is not prohibited, a very good lightning effect can be obtained
by arranging a file and a piece of carbon as opposite poles of the
circuit and scraping them together. It is a bad practice, however, to
strike an open arc on any stage. There should always be wire mesh around
it to prevent the escape of sparks.
Automatic strikers can be purchased which will make an open arc lamp
produce good lightning effects. Another method of producing lightning is
that of flashing some of the border lights. This will do in an emergency
but does not compare with the other methods. Sometimes the effect of a
bolt of lightning striking a certain place is imitated by an arc sliding
swiftly down a wire. In order to strike the arc at the proper moment,
the apparatus being somewhere up in the flies, a small fuse is connected
from one carbon to the other. The current when turned on passes through
the fuse, melts it, and establishes the arc. The carbons are incased in
a very small wire-mesh enclosure and the whole device is made to slide
swiftly down a tight wire leading to the proper place. The more
pretentious shows often use several lightning machines to avoid the
monotonous effect of all lightning strokes coming from the same
direction. One resistance may be made to serve for any number of
lightning machines provided only one machine is used at a time.
[Illustration: FIGURE 201.]
_Lugs._--Lugs must be provided for all leads where more than 30 amperes
are used. It is even more necessary to follow this rule in connection
with portable theater equipment than with other wires because they are
more apt to work loose.
For the connections to the arc lamp and rheostats it is not practicable
to use soldered lugs because no solder will stand the heat. Two styles
of lugs that may be used are shown in Figure 201. The cuts will also
explain the manner of connecting the lugs. At the left, the bare lugs
are shown; in the center the copper of the conductors is shown inserted
into the lugs, and at the right the whole conductor is shown bent back,
the metal of the lug catching over the insulation to keep it from
fraying out. The wires feeding arc lamps are always asbestos covered and
this covering fits loosely to the wire and must be held in some such
manner. A stock of such lugs should always be carried, as the leading-in
wires to arc lamps, using heavy currents, frequently burn off.
[Illustration: FIGURE 202.]
_Moon Boxes._--These boxes are generally made up as shown at the left in
Figure 202. The opening is from twelve to fourteen inches in diameter.
Four lamps give very good illumination. The frame must be provided with
hooks so that it may be suspended at any desired part of the scenery. It
is always hung close behind a curtain and must be so arranged that the
lamps cannot touch the curtain. The wires should be entirely enclosed
in metal of No. 20 sheet metal gauge after the manner of strips. Very
cheap productions often carry moon boxes made up of an incandescent lamp
fastened in a tin dish, similar to the one shown at the right in Figure
202.
_Moonlight on Water._--This and all similar effects can be produced
through the “Sciopticon” but this requires the use of an arc lamp and is
expensive. A cheap way of producing the effect is illustrated in Figure
203, which represents a metal cylinder, perforated as shown, inside of
which there are a number of incandescent lamps colored to suit. The
cylinder is slowly revolved and the moving shadows and streams of light
thrown upon the scene produce the effect.
[Illustration: FIGURE 203.]
[Illustration: FIGURE 204.]
A somewhat similar method of producing this effect, as also that of a
waterfall, is illustrated in Figure 204. In this case a spiral capable
of being moved by clock work is revolved about an electric lamp and
gives the effect of falling water. Both of these devices work behind
curtains.
_Musical Acts._--There are numerous musical acts upon the road in which
the beat of the music is emphasized by lighting colored lamps in time
with the tunes. It is advisable to arrange all such acts to operate by
batteries. In many places inspectors will not allow high-voltage
contacts to be used open, and it is often difficult to enclose them in a
practical manner. By using dry batteries the apparatus is taken out of
the jurisdiction of inspectors and all danger of fire is also
eliminated.
_Musical Bells._--Sets of musical bells properly tuned and connected to
a keyboard from which they can be operated electrically are carried in
stock by dealers in theatrical supplies. Sets are usually made up of
eighteen bells and they may be played from a distance.
_Oil Lamps._--These have been imitated by arranging a small battery
inside of the base of the lamp. This battery would supply current only
during the short time that the lamp was being carried about. The base of
the lamp is also fitted with electrical contacts which rest upon similar
contacts fitted into the table, and through which the lamp is kept
burning by a storage battery while it is resting upon the table. A small
dry battery, such as is placed in the base of an oil lamp, would not
keep the light burning for a long enough time.
_Pin-Plug Connectors._--These are provided to connect cables to effects
used on the stage. The essential points of a good connector are: It
should grip the whole cable, thus making it unnecessary to strip the
outer braid from any exposed part of the cable; and it should offer no
live screws or contacts on the outside. These conditions are fulfilled
by the connector shown in Figure 205. In some of these connectors,
however, the part that grips the cable (indicated by the arrow) is made
of metal, and this, if forced down too tight, may cut into the cable
and cause a short circuit. Several instances of this kind have been
known to occur. Pin-plug connectors must always be connected so that the
projecting pins are dead when the plug is disconnected.
[Illustration: FIGURE 205.]
[Illustration: FIGURE 206.]
A special warning against the use of such connectors as are illustrated
at the right of Figure 205 is necessary. Their cheapness brings them
into use very often, especially with acts that do not carry competent
electricians. The wires are always working loose; projecting ends are
bare, and if the connector is twisted, a short circuit results. Where
they must be used in an emergency, they should be heavily taped, the
tape being placed between the conductors and all around the plug, as
shown in the figure.
Branch-off connectors such are shown in Figure 206 are often used to tap
off lights from the main cable. Where plug connectors are used for arc
lamps they must be made up as shown in Figure 207. The asbestos-covered
wires necessary to be used with arc lamps cannot be used in cable but
must be separately connected.
[Illustration: FIGURE 207.]
_The National Electrical Code Rules for Pin-Plug Connectors._
Must be of an approved type, so installed that the female part of the
plug will be on the live end of the cable, and must be so constructed
that tension on the cable will not cause serious mechanical strain on
the connections.
_Plugging Boxes._--Plugging boxes are used to obviate the necessity of
running a large number of wires over the stage to the different stage
pockets. They are also a necessity because many theaters are not
equipped with a sufficient number of stage pockets to accommodate all of
the devices large productions carry. The plugging box should be
fireproof; should have self-closing doors so that there may be no
liability of open fuses being left among the scenery where they are
used. Most of the plugging boxes in use at the present time are arranged
for link fuses. A link fuse, however, requires more time to install than
a cartridge fuse and the latter would therefore seem much more
desirable. A cut of a much-used plugging box is shown in Figure 208.
[Illustration: FIGURE 208.]
_The National Electrical Code Rules for Portable Plugging Boxes._
Must be constructed so that no current-carrying part will be exposed,
and each receptacle must be protected by approved fuses mounted on slate
or marble bases and enclosed in a fireproof cabinet equipped with
self-closing doors. Each receptacle must be constructed to carry thirty
amperes without undue heating, and the bus-bars must have a carrying
capacity equivalent to the current required for the total number of
receptacles, and approved lugs must be provided for the connection of
the master cable.
_Rheostats._--Portable stage equipment being intended for use in all
parts of the country must be adjustable to all kinds of lighting
systems. For this reason it is not practicable to use auto-transformers
as is commonly the case where arc lamps are fed from alternating-current
circuits. Simple rheostats or resistances are therefore always used.
With these it is immaterial whether the current be alternating or direct
except in so far as the quantity is concerned.
Alternating current being less efficient in the production of useful
light than direct current, the amperage must be greater and this
produces a greater loss in voltage, the loss being always proportional
to the product of current times resistance. The drop in voltage over a
certain resistance is therefore always greater, when an
alternating-current arc is used, than it is with direct; but as the
alternating-current arc operates at a lower voltage than the direct this
is not objectionable and simple resistances give satisfactory results
whether used with one kind of current or the other. The traveling show
must also be prepared for different voltages and a suitably arranged
group of resistances is very convenient in this respect.
Figure 209 shows a box made by the Chicago Stage Lighting Company
containing a number of resistances which may be connected in various
ways to obtain different results. In Figure 210 at _A_ is given a
diagram representing the wire in a single section. One such section
placed in series with an arc lamp will give a certain current. If we
connect two of them in parallel, as in _B_, we shall obtain not quite
double the current, since this arrangement does not affect the
resistance of the arc which also influences the current strength. If the
connections are made as in _C_, we shall have but half the current
obtainable by the use of one section, or the same current in case we are
dealing with double the voltage. If _A_ is suitable for 110 volts, then
_C_ is suitable for 220 volts and _D_ for 550. In _E_ we have the
connection which would give us, for 220 volts, the same current _B_
would give with 110. It can thus be seen that a group of such
resistances can be made to fit an arc lamp to almost any voltage that is
likely to be met with.
[Illustration: FIGURE 209.]
Nothing but metal and porcelain must be used in the construction of
these resistances and they must be on stands which raise them well above
the floor. The connections to the resistances should ordinarily be made
with asbestos cable. It is necessary to keep close watch of the wire
used to make up the resistance especially if it becomes very hot during
a run. A resistance in which the wire becomes red hot should not be
used. There are productions in which it is necessary to place the arc
lamps and their rheostats directly in the way of flying paper used to
make “snow”. In such cases the resistances must be tightly enclosed.
This destroys the ventilation and they will readily become overheated.
For use with such productions resistances may be specially wound and
arranged, or they may be made separate from the arc and placed in a safe
location.
[Illustration: FIGURE 210.]
_Stage Cables._--Stage cables are subject to very rough usage, but there
are some very good makes on the market, and by purchasing the best, one
can expect long service. Cuts of various kinds of cable likely to be
used upon the stage are given in Figure 211. _A_ is the ordinary stage
cable; _B_ is used for heaters; _C_ is reinforced cord; and _D_ is the
parallel cord. The last two must not be used on the floor. The size of
the wire to be used depends upon the apparatus which the cable must
supply and can be determined from Table VII which gives the carrying
capacities. Only approved cables should be used.
[Illustration: FIGURE 211.]
_Strips._--Strips are used for the illumination of special parts of the
scenery. They usually contain from one to twelve lights. A strip is
subject to rough usage and should be strongly made. Cuts of several
kinds of strips are given in Figure 212. The chief trouble with strips
is found to be in the working loose of screws which hold the sockets in
place, and the connection at the point at which the cable leaves the
strip.
_The National Electrical Code Rules for Strips._
Must be constructed of steel of a thickness not less than No. 20 U. S.
sheet metal gauge, treated to prevent oxidation, and suitably stayed and
supported and so designed that flanges will protect the lamps.
[Illustration: FIGURE 212.]
Cables must be bushed in a suitable manner where passing through the
metal, and must be properly secured to prevent serious mechanical strain
on the connections.
Must be wired in approved conduit or armored cable, each lamp receptacle
being enclosed within an approved outlet box, or the lamp receptacles
may be mounted in an iron or steel box, metal to be of a thickness not
less than No. 20 U. S. sheet metal gauge, treated to prevent oxidation,
so constructed as to enclose all wires. Wires to be soldered to lugs of
receptacles.
[Illustration: FIG. 213.]
_Sunrise._--Sunrise effects may be produced by means of the Sciopticon,
but a cheaper method is often resorted to. This is illustrated in Figure
213 and consists of a roll of suitably colored silk which may be
unrolled in front of an arc lamp. To produce sunrise it is unrolled in
one direction, the darkest colors coming first and gradually giving way
to lighter. For sunset it is worked the other way. In special cases a
similar sheet of colored silk wide enough to cover open arcs has been
stretched from the floor to the top of the scenery and several arc lamps
arranged behind it in such a manner that they could be gradually raised,
thus producing the same effect with more impressiveness, but with a much
greater quantity of light.
[Illustration: FIGURE 214.]
[Illustration: FIGURE 215.]
_Switches._--Knife switches on the stage are generally required to be
enclosed. It is not sufficient to provide a box with a cover that can be
closed, but the switch should be in a box which need not be opened to
operate the switch. See Figure 214. Often it is necessary to install
switches in a length of stage cable so that the switch may be portable.
Such switches should be installed as shown in Figure 215, in which a
flush switch is shown in a regular metal enclosure.
[Illustration: FIGURE 216.]
_Table Lamps._--The table lamp is a small device, but it causes a great
deal of annoyance and trouble. The bottom of the lamp should be enclosed
with metal, especially if there are any splices. The stem where the wire
enters should be well reamed out (see the arrow in Figure 216) and there
should be a strong well-fastened bushing where the wire leaves the lamp.
The hard-rubber bushings which come with the common table lamps do not
remain in place very long and are frequently broken or lost. Stage cable
is generally required upon the stage, but it is customary, in connection
with these lamps, to allow a good grade of reinforced cord or even fine
silk-covered cord, provided it is not long enough to trail on the floor
where it might be stepped upon. The glass shades which are often called
for in connection with the lamps also cause much trouble; and to avoid
this trouble, colored gelatine has been used, backed up with fine wire
screen to keep it in place. This of course cannot always be done because
many lamps are not suited to it.
_Time Beaters._--This is a small keyboard located at the orchestra
leader’s stand; it controls the light which may be back of the stage and
indicates the time to the chorus behind scenes.
_Water Falls._--The devices shown in Figure 204 for use as moonlight on
the water can also be used to produce the effect of a waterfall or of
water rippling downstream.