Automotive wire in controle panel build?

[SavageBrewer]

I asked this question before in a reply but did not get an exact answer. I am building a control panel that will run on 240/120 volts at 30 amps max. Really the load draws closer to 20 amps. I have about 100 feet of 10 gauge automotive wire. First, can this wire be used inside the control panel? Second, what is the difference between automotive wire and household wire, other than the thickness of the strands? I am calling on all those electrical gurus to help me with this one please.

 

[bolts]

I asked this question before in a reply but did not get an exact answer. I am building a control panel that will run on 240/120 volts at 30 amps max. Really the load draws closer to 20 amps. I have about 100 feet of 10 gauge automotive wire. First, can this wire be used inside the control panel? Second, what is the difference between automotive wire and household wire, other than the thickness of the strands? I am calling on all those electrical gurus to help me with this one please.

I used marine wire (local source, flexible, it was nice) -- however the key considerations are if it's rated for the amperage, voltage and environment. In my case it is rated for 300V and it was appropriate for the temp/environment. I used 10 gauge pre-fused and 16 gauge after fuses (1a and 2a fuses).

Somebody else will chime in I'm sure If I've misguided you

 

[SavageBrewer]

Well I don't have a rating for voltage on the wire. I know it is used for transit buses. I don't know. I guess I will find out when I power it up for the first time.

 

[thargrav]

If the insulation is under-rated you may not know right away - it may fail later. You need to find out it's rating before you use it.

 

[porcupine73]

Main difference will likely be the insulation. It probably does have enough dielectric strength and heat rating to use it, but if the wire does not have anything printed on the insulation, I would not use it in this application. Inside the panel you can't need too much wire right, so I would spend the few $ and just get the appropriate THHN, THWN etc. insulated wire in bulk at the hardware store.

 

[RichBenn]

I say don't use it. It will handle the current (amps), but there are different standards for insulation for 12V automotive vs. 240 V.

 

[SavageBrewer]

So I used an Ampprobe mega ohm meter on insulation test. Set the test for 1000 volts. Attached the positive lead to the wire and the negative lead to the insulation. Ran the test and the results were O. L. ( out of limit.) This concludes that the insulation should be adequate. Now I feel more comfortable about using the wire. Thanks for all the help everyone.

 

[RichBenn]

So I used an Ampprobe mega ohm meter on insulation test. Set the test for 1000 volts. Attached the positive lead to the wire and the negative lead to the insulation. Ran the test and the results were O. L. ( out of limit.) This concludes that the insulation should be adequate. Now I feel more comfortable about using the wire. Thanks for all the help everyone.

Did you read the other posts?

I can get almost any insulation to survive 1000V, but that doesn't mean it's safe or recommended in a given application. There are many elements involved in getting an insulation rating - heat, flammability, dielectric breakdown, abrasion resistance, etc.

BTW, just so you know I'm not blowing smoke, I designed electronics products for industrial applications for 25 years. I wouldn't put that wire in my control box. Spend the extra and do it right.

 

[SavageBrewer]

Did you read the other posts?

I can get almost any insulation to survive 1000V, but that doesn't mean it's safe or recommended in a given application. There are many elements involved in getting an insulation rating - heat, flammability, dielectric breakdown, abrasion resistance, etc.

BTW, just so you know I'm not blowing smoke, I designed electronics products for industrial applications for 25 years. I wouldn't put that wire in my control box. Spend the extra and do it right.

Sorry about that. I was just wondering if the test was a good way of seeing if the wire was ok to use. I am going to use THHN wire instead. I understand that the risk of using inferior wire is not worth it. Thank you again for all the help.

 

[porcupine73]

So how'd it go? The toughest situation for the insulation would be where it is near another conductor of a different phase, or less so, ground. If it's just spaced > 1 inch in air it will probably be fine, but if it is resting against the metal grounded panel anywhere, I would not want any unrated/unknown insulation that case, though 120V rms to ground is not likely to cause an issue ... you certainly wouldn't do that in say 480V phase to phase or higher, the risk gets much higher that it will punch right through inferior insulation ... the megger test can be helpful, but ideally the wiring needs to be very close something grounded ... else it isn't very likely it will leak much just into the air < 1000v. Megger tests are much more informative in shielded cable for like >10kv applications thought it can indicate obvious issues with lower voltage / unshielded cabling as well.

 

[SavageBrewer]

So how'd it go? The toughest situation for the insulation would be where it is near another conductor of a different phase, or less so, ground. If it's just spaced > 1 inch in air it will probably be fine, but if it is resting against the metal grounded panel anywhere, I would not want any unrated/unknown insulation that case, though 120V rms to ground is not likely to cause an issue ... you certainly wouldn't do that in say 480V phase to phase or higher, the risk gets much higher that it will punch right through inferior insulation ... the megger test can be helpful, but ideally the wiring needs to be very close something grounded ... else it isn't very likely it will leak much just into the air < 1000v. Megger tests are much more informative in shielded cable for like >10kv applications thought it can indicate obvious issues with lower voltage / unshielded cabling as well.

So, I decided to replace all the auto wire with thhn 600 volt wire. After calling the manufacturer of the auto wire, they told me they didn't know the voltage rating of their own wire. That kind of scared me so I played it safe and took the advice of everyone and used the proper wire. It didn't cost that much more but the work of removing the old wire and installing the new wire was a pain. I should of just used the right wire in the first place. Lesson learned. Thank you for all the help everyone. You guys are great.

 

[FTG-05]

Good decision. There are certain things in life you can fork with and get away with it. Electricity isn't one of them.

Good luck with your project!