The following information is provided to assist in designing proper emergency lighting systems effectively and economically by using the smallest permissible wire size for load circuits.
When remote lighting fixtures and/or exit signs are connected to emergency lighting units, circuit runs must be of sufficient size to maintain a proper operating voltage to all lamps.
The National Electrical Code limits voltage to drop to a maximum of 5% of nominal. The Wire Size Guide Catalogue Sheet is a table that lists the maximum
length or wire run based on systems voltage, wire gauge and total wattage on the run.
To determine the maximum length of a wire run not listed, divide the
value of the load in watts into the constant listed at the bottom of each row.
Example, the maximum wire run for #10 wire on a 12 volt system, with a 54 watt load,
is 3397 ÷ 54 or 62 feet.