lights and motors

Printed From: the12volt.com
Forum Name: Lights, Neon, LEDs, HIDs
Forum Discription: Under Car Lighting, Strobe Lights, Fog Lights, Headlights, HIDs, DRL, Tail Lights, Brake Lights, Dashboard Lights, WigWag, etc.
URL: https://www.the12volt.com/installbay/forum_posts.asp?tid=822
Printed Date: July 05, 2025 at 3:39 AM

Topic: lights and motors

Posted By: sbean31
Subject: lights and motors
Date Posted: May 17, 2002 at 7:30 PM

I have branched into emergency vehicle installations for local PD and fire depts. I am having trouble with overheating in the power block. After a period of time, the wire is melting the fuse block. I currently use 4 awg PWR and GND. The lights are capable of drawing 80 amps at max draw. Any suggestions for keeping the wire from meltdown status.

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admit nothing,deny everything
make counter-accusations

Replies:

Posted By: the12volt
Date Posted: May 18, 2002 at 7:32 AM

Hi sbean31, the 4 gauge wire is more than adequate for the amount of current draw you have. What type of fuses and fuse block are you using? If you're using an ATC or AGC type fuse and fuse block, you should step up to an AGU or ANL type fuse and fuse block. Let us know.

the12volt

Posted By: HotRod53F100
Date Posted: May 18, 2002 at 8:10 PM

Also to add to what has already been said, anytime that you have a loose or bad connection, you get heat. Make real sure that everything is as clean and tight as possible. When you get to higher amps like you are, any loose connection will generate heat.

As I look at my spec book...4 gauge single strand copper wire is good for 105 amps but 4 gauge 3 strand copper wire is rated for 70 amps. This info was originally extracted form the National Electrical Code. Maybe your not large enough?

The problem that you describe sounds like a connection problem to me, especially if it only melts on the end. An overcurrent situation will allow it to melt anywhere along the wire, not just on the end.

Good Luck!

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HotRod

Posted By: markb
Date Posted: May 20, 2002 at 12:02 PM

sbean31- Hey, I do Police cars and stuff full time for EECo. If I read your question right, I have a solution. First of all, use an adequate breaker right at your 12-volt source. Then run that to a big ol' power relay switched at ignition or with an override. use this to power up your fuse panel. I use breakers on all high current wires. I only fuse the low amp wires I use to control my relays for components. The way I see it, the fewer high current wires in the cab the better. I actually use 75 amp relays and breakers for my high draw lights. No problems. Only switch your low current relay control wires for activation.

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-Mark