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I recently added a relay for the high beams on my 1961. The lights would flicker before adding the relay is why the relay was installed and the lights work well now. I've felt the wires after the relay to make sure nothing is ready to burn and the wires have felt warm, which I expected. But how warm should they be? I've used an IR gun to measure the wire temps, but I have no base line.
Does anyone have an idea of the temp range to look for?
I recently added a relay for the high beams on my 1961. The lights would flicker before adding the relay is why the relay was installed and the lights work well now. I've felt the wires after the relay to make sure nothing is ready to burn and the wires have felt warm, which I expected. But how warm should they be? I've used an IR gun to measure the wire temps, but I have no base line.
Does anyone have an idea of the temp range to look for?
TIA.
If any wire is detectably warm, it is undersized for the amount of current it's carrying.
Let's go back to this flicker you were trying to address with the relay. To me a flicker indicates an intermittent condition, not low light output. The usual relay mod is intended to provide more current to the headlights without overpowering the headlight switch. So I'm wondering what specific mods you made to the wiring, and why that would address the flickering problem. ... I guess I'm saying there is more to this than warm wires, but I"d be hesitant to use those circuits until everything is sorted out.
If I remember correctly, the wires to the headlights are 18 gauge and should be good for 5 amps.
What headlamps are you using? You need to connect an amp meter and measure the current draw.
Another problem if you are using the old wiring harness is that the stranded wires tend to break at the connectors, so you might check wires where they are crimped onto the connectors and see if any strands are broken.
Charles
If I remember correctly, the wires to the headlights are 18 gauge and should be good for 5 amps.
Charles
My memory is that high beams consume about 55 Watts, whether standard or halogen. That's nearly 4 Amps if the generator is producing ~14 Volts. If both our memories are functioning properly, 18 ga. wire wouldn't have a lot margin.
My memory is that high beams consume about 55 Watts, whether standard or halogen. That's nearly 4 Amps if the generator is producing ~14 Volts. If both our memories are functioning properly, 18 ga. wire wouldn't have a lot margin.
They are the original wires. The relay's purpose is to take the load off of the light & dimmer switch since they're only required to carry enough to energize the relay.
Let's go back to this flicker you were trying to address with the relay. To me a flicker indicates an intermittent condition, not low light output. The usual relay mod is intended to provide more current to the headlights without overpowering the headlight switch. So I'm wondering what specific mods you made to the wiring, and why that would address the flickering problem. ... I guess I'm saying there is more to this than warm wires, but I"d be hesitant to use those circuits until everything is sorted out.
No mods to wiring circuit. I'll check the current draw.
The flicker was from the breaker in the headlight switch opening and closing due to current flow through it.. Adding the relay moved the current draw out of the headlight switch and to the relay outputs. Very common issue and very common fix. The question as to wire temp is directly related to wires not large enough for continuous draw from the lights. Warm won't hurt anything, but larger wire will not get as warm.
Adding the relay should have made the lights brighter and brighter means more current through the wire.More current through the wire means warmer wire. Larger wire means cooler wire. I think you may be chasing a problem that is not a problem.
Last edited by 65GGvert; Nov 24, 2020 at 02:33 PM.
They are the original wires. The relay's purpose is to take the load off of the light & dimmer switch since they're only required to carry enough to energize the relay.
I'm a EE; I understand how it all works.
Others' comments not withstanding, no wire in your car should get warm to the touch. The only possible exception would be the (+) cable to the starter. With extended cranking, it will get warm.
For your headlight wiring, you should determine if the current being drawn by the headlights is normal. If it's too high, determine why and fix that.
If the current is not abnormal, consider replacing the wire which is getting warm with a wire which is at least one size larger. e.g. if it is currently 18 ga, replace it with 16 ga.
I have read elsewhere on this forum about aftermarket light switches that activate the circuit breaker under "normal" loads, so perhaps that was all that was happening. But it is also conceivable that the circuit breaker was activating because there was an unusally large load on the circuit. For example, a small or intermittent short circuit could add to the normal load. If that were the case, that could account for the warm wire after the relay was installed. .... Data on the current draw should show whether or not this is the case.
You can't go wrong with 10ga, just about everywhere. The engineers job, is to minimize cost and weight and use the smallest suitable wire for any given application.
Remember, $1 saved on each of 10 million cars is $10 million more profit.
Others' comments not withstanding, no wire in your car should get warm to the touch. The only possible exception would be the (+) cable to the starter. With extended cranking, it will get warm.
For your headlight wiring, you should determine if the current being drawn by the headlights is normal. If it's too high, determine why and fix that.
If the current is not abnormal, consider replacing the wire which is getting warm with a wire which is at least one size larger. e.g. if it is currently 18 ga, replace it with 16 ga.
Jim,
I'm not saying you're wrong.. but you have to agree that every wire carrying any current warms.. "feeling warm" means different things to different people.
An average person can perceive a 1 degree F change in temp.
I often feel a cord/wire to get a sense for how much current is flowing.
The cord to my vacuum cleaner gets pretty damn warm.
If any wire is detectably warm, it is undersized for the amount of current it's carrying.
See now this is what you get from an engineer. Jim knows that if the plastic insulation on a wire is warm than the copper conductor it covers is hot. A hot conductor is giving up what might otherwise be light to heating a wire. And the margin for safety is exceeded, a wire that runs hot will likely burn its insulation during a momentary short and go up in an instant if a hard one. Those are two good reasons not to design a circuit with undersized conductor.
On the other hand mass produced goods by necessity are engineered to use the smallest possible wire size and length given copper is a commodity. I have many cars with factory wiring that is woefully deficient mostly in the blower and charging and ammeter areas, our Corvettes are no strangers to it either.
65Gvert is correct however, it really isn't a problem. Its how they did it.
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Wire Temperature
