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The Basics of Electricity
Electrical power is often the limiting
factor when determining how much lighting and sound can be
done in a particular venue. It is important not to assume
that sufficient power is always easily accessible. Many buildings,
both new and old, do not have enough electrical service to
power large, elaborate shows.
One of the first steps in audiovisual
planning is determining the amount and kind of electrical
power that is available. The number of receptacles (outlets)
is not an indication of the amount of power available. Without
a wiring diagram, you cannot know whether each receptacle
represents a separate circuit, or (at the other extreme) every
outlet is on the same circuit. When doing a site evaluation
or walk-through at a venue, ask that the house electrician
be available for your audiovisual contractors to meet with.
The electrician will be able to answer their questions regarding
the type, amount and location of electrical power in the venue.
This information will help the contractors provide you with
accurate estimates as to the amount of equipment they can
safely and reliably power using house power. If there is not
enough power in the venue, your contractors will suggest renting
a portable electrical generator to provide electricity for
the event.
A quick
high school physics refresher
Wattage = Volts
x Amps
Wattage
is the amount of power it takes to power a device; the quantity
of power. A 100-watt bulb requires 100 watts of power.
Voltage
is the density at which power flows through electrical cable.
120 volt is the common household voltage.
Amperage is the speed
at which the power moves through electrical cable.
Essentially, power = density x speed.
The denser and more quickly that power is delivered, the stronger
it will be.
There are many different factors that
determine the viability of house power for your event. One
common event planner mistake is to get one piece of information
and assume the rest. Just because the building gets "industrial
strength" voltage (220v) instead of "household level"
voltage (120v) does not mean there will be enough. The presence
of 20 amp circuits (as opposed to 15 amp circuits) does not
guarantee plentiful power. All of the factors together, including
the number of circuits, determine total wattage available
for lights, sound, and other uses at an event.
When discussing electrical power with a venue,
ask if there are separate charges for electricity and, if
so, make certain that these charges are presented to you (in
writing!) for approval prior to the event. Hotels are notorious
for adding significant charges for electrical power (hundreds
of dollars or more) without prior notification. Although any
responsible audiovisual company will alert the planner to
the possibility of suhc charges, because the discussions generally
take place with a hotel electrician, your contact at the hotel
(or other venue) may not know what your contractors have ordered
until after the event. Avoid surprises and ask about it early.
Discuss electrical power requirements
with your venue staff as well as your contractors early in
the planning process to avoid last-minute surprises.
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