Electrical question help please!

[Dulcesuenos]

I was checking our wiring had an issue with a gauge light. And noticed the feed wire to our navigation lights switch is warm. Yes our nav lights are on we are doing an overnight. The wire is about a #8 maybe a 6. Is this normal? It wasnt red hot but fairly warm. Not a place to be concerned miles offshore in the dark...

[Sandero]

#6 of #8 awg for lighting an instrument? That's insanely thick.

[Dulcesuenos]

Its whatever size fits a yellow butt splice connector.
And it's the feed wire for the nav lights switch, theres a mid mast light two forward running lights and a stern running light 4 lights total about 35+' apart biggest concern is should the wire feeding the switch be warm?

[St. Elsewhere]

For an 8 or 6 ga wire to get warm would require 40 amps, or more flowing through it. Could the heat have come from something else? I would verify the size of the wire, and put an amp clamp on it to read the current flow. If there is that much current in it surely there is more than nave lights involved.

[Dulcesuenos]

Maybe its a #10 wire then.

[Kettlewell]

Yellow connectors are usually for 10-12 gauge wire. If they are regular incandescent bulbs they could all be around 25 watts or 2 amps each, meaning a total of 8 amps. It would be worth it to put an amp meter on the line with the lights on to see what it reads, and do the same with the lights off.

[model 10]

Where are you? Perhaps it's hot out. You should place a cold beer in one hand and a #10 wire in the other.

[Dulcesuenos]

Ty kettleworth, lol Guy, were off Pine island heading to our new berth in the keys.

[Ziggy]

3 incandescent nav lights could draw as much as 8A in total (25W each).
Yellow insulated terminals are usually for AWG #10 or #12 wire.
I could definitely see how a #12 wire could get warm.

[Dulcesuenos]

Originally Posted by Ziggy

3 incandescent nav lights could draw as much as 8A in total (25W each).
Yellow insulated terminals are usually for AWG #10 or #12 wire.
I could definitely see how a #12 wire could get warm.

Is it a concern?

[St. Elsewhere]

Originally Posted by Dulcesuenos

Is it a concern?

At 8 amps a #12 wire should not get warm. If it is quite warm the concern would be that current is going somewhere else too. If it is not real hot the concern is not fire safety, but if it is drawing 20 amps (the level where a #12 gets warm) the battery is going down a lot faster than it should for running nav lights.

[Zil]

12 awg wire will carry 23 amps for 40 feet (or more) and stay at ambient temperature.

[Cheechako]

Probably a #10. A little warm is not the end of the world. The best fix may be to go to more energy efficient bulbs in your lights.

[Wotname]

Is there a terminal connector or a switch or circuit breaker near where you are feeling the heat?

It is possible you have some unwanted resistance (corrosion etc) which is getting hot and the heat is travelling along the wire. Run your hand (carefully & slowly) along the wire in either direction to see if the temperature changes at any point.

[Dennis.G]

Originally Posted by Zil

12 awg wire will carry 23 amps for 40 feet (or more) and stay at ambient temperature.

Actually, any wire with a current must be above ambient temperature. Temperature rise will be proportional to I^2*R. Actual temperature rise will depend on effectiveness of losing the generated heat (i.e., in free air, in conduit, in a wire bundle, type of insulation etc.).

For 12 AWG a simple calculation (with assumptions) is:

Temp rise (in C) = I^2 * 0.0365

for 10 AWG use 0.0208