[Shiner]

We have been using welding cable for motor lead wire and to wire through drives and associated components for years due to its flexibility and increased ampacity rating vs thhn of the same AWG or O . Recently it came about that this was no longer a recommended use for the cable without explanation. Does anyone know the reasoning behind stopping this use?

[RussB]

Shiner, on 08 August 2012 - 10:26 AM, said:

We have been using welding cable for motor lead wire and to wire through drives and associated components for years due to its flexibility and increased ampacity rating vs thhn of the same AWG or O . Recently it came about that this was no longer a recommended use for the cable without explanation. Does anyone know the reasoning behind stopping this use?

Likely because companies like Lapp and others sell a cable, similar but better suited for this application. Of course you pay a little more for it than THHN but likely less than welding cable.

[Shiner]

I know there are alternatives, this just happens to be a size thing on our end where we have done many of these the same. Now we are being told by listing agencies, not by cable manufacturers, that welding cable is no longer acceptable. UL lists it in their handbook as an acceptable use, so I was trying to find out why they are going away from this. Could it be something with the amount of stranding vs how much drives are being used in motors now and the frequency of the switching does something with the skin effect of the higher strand count.....pulling at straws here but we kind of want to know the engineering behind this decision.

[RussB]

Shiner, on 08 August 2012 - 01:31 PM, said:

I know there are alternatives, this just happens to be a size thing on our end where we have done many of these the same. Now we are being told by listing agencies, not by cable manufacturers, that welding cable is no longer acceptable. UL lists it in their handbook as an acceptable use, so I was trying to find out why they are going away from this. Could it be something with the amount of stranding vs how much drives are being used in motors now and the frequency of the switching does something with the skin effect of the higher strand count.....pulling at straws here but we kind of want to know the engineering behind this decision.

Ask the agency that states that it is not approved. They likely have no valid scientifically provable reason, or it is because the weld cable producers do not want the expense of their testing as it will add price to the weld cable and put it out of competition with other weld cable producers who are not interested in selling their welding cable against the "approved" industrial cable manufacturers.
In other words it is likely do to more governmental regulations, as I tried to imply in my first "PC" reply. :(

This post has been edited by RussB: 08 August 2012 - 03:25 PM

[drforsythe]

This is just a guess, but weld applications are typically very low voltage with very high current for short durations. Drive applications have high voltage output (spikes to 1.5xVin) and constant current levels. Could it be that the jacketing on weld cables are not rated for the high spikes that drives produce? That is one of the key reasons for purchasing inverter-rated motors over standard motors.

[OkiePC]

You want DLO cable. Same stuff as far as workability, with good ratings, listings and of course higher price, 2KV rated is what we've used, it's easy to work with, at certain sizes may require special attention when selecting crimp lugs, but get the word welding out of your spec and all will be fine except the dent in your wallet. You can also get it cabled for large motors with various numbers of power wires for AC and DC motors.

Generic Google Results for Diesel Locomotive Cable: https://www.google.c...iw=1278&bih=754

This post has been edited by OkiePC: 10 August 2012 - 08:28 PM

[Giz99]

You will find that the welding cable does not have any rating on it. If you look in your electrical code you will not find welding cable mentioned for continuous current carrying applications. The DLO able is a great multi strand cable but it can be expensive.

[Mendon Systems]

I have been using Radnor welding cable for that application. It is rated for 600 volts and 105 C.
Radnor cable
I suspect that RussB has the correct answer. The people that make DLO cable greased a few palms!

This post has been edited by Mendon Systems: 27 September 2012 - 04:00 PM

[cHud]

Think the main reason was mentioned above. Typically welding cables are rated to 600V. Where as normal motor cables are usually rated to 1000V.

[Giz99]

The insulation on welding cable is not designed for continuous use. My electrical inspector will fail any installation which uses welding cable for a non welding application. His reasoning is that it is not identified in any of the tables in the electrical code.

[marcinski]

For application like yours we are using only two kinds of motor lead wire.
1. SRML wire for high temperature, hazardous locations and flexibility.
2. Sil-a-blend from Radix, same as above.
Never had anybody complain.