Electrical wiring for Landing lights

G

Gary Brink

New member
I am finishing my second wing on a 14-13-2 and am in the process of putting in the landing lights. There are no old wires in the wing but it looks like there were two wires. Why couldn't I use one heavier wire with a the braided metal shield to run the lights? Simply use the shield for the ground and the wire to the "hot" side of the light. Then I could run a six inch "jumper" for the hot and another to the ground on the second light? I assume there is a reason for two wires so can someone straighten me out? :?
Gary
 
Gary, good idea BUT it won't handle the amperage. Do this and run the lights for some time and you will pop the breaker. Keep it up and you will have a smoker. Two 16 gauge wires one hot ,one ground and you will be ok. Landing lights like auto car lights draw a lot of current so protect your plane and yourself. Curses RED BARON. :mrgreen: LYNN
 
I would guess that the two wires were there for each of the two lights - landing and taxi. Both were probably shielded wires running from separate switches out to the lights.

Assuming that each of the lights will be 100W bulbs, I went to the trusty AC-43.13 and ran the numbers. 100W @ 13 volts comes out to just under 8 Amps per bulb. Using 10 Amps as a safety factor, and a 0.5 V drop for 25 ft (12 ft out, 12 ft back), the Feds say that #12 wire would do it for each light under continuous operation. Running the derating values for bundled wire (shielded wire is about as tight a bundle as you can get two wires into), I computed that the 2 wire bundle of #12 wire running at 100% power could handle 30 amps max without overheating a MIL-Spec wire rated at 150 deg C at 10,000 ft at ambient of 60 deg. C.

This was a quick computation and you should run the numbers yourself to be sure, then run them past a friendly IA for further verification.

Dave York
 
You must log in or register to reply here.
Back
Top