Use of weld cable

[dm9289]

We are getting materials together for a VFD installation, and we wanted a wire that was flexible. This cable will be in its own conduit to avoid interference. The price of the VFD specific cable was in the $40 per foot range for 250kcm so the local warehouse suggested using weld cable. In 630 IV I did not see it as being prohibited but it just did not seem correct any help out there?

Thank you
Dave

 

[augie47]

NEC recognized conductors are listed in Table 310.104(A).
It''s double your "weld cable" will be there but it is possible it has a recognized rating also.
Often for flexibility folks will use "DLO" cable which has the recognized "RHW" rating also.
There is, however, a lot involved in VFD cables other than flexibility.

https://www.southwire.com/products/DLODieselLocomotiveCableoem.htm

 

[don_resqcapt19]

We are getting materials together for a VFD installation, and we wanted a wire that was flexible. This cable will be in its own conduit to avoid interference. The price of the VFD specific cable was in the $40 per foot range for 250kcm so the local warehouse suggested using weld cable. In 630 IV I did not see it as being prohibited but it just did not seem correct any help out there?

Thank you
Dave

Welding cable, unless additionally marked at RHW of RHH (or other insulation type found in the NEC) cannot be used for NEC applications. Also note that standard terminations are not suitable for use with finely stranded conductors like this.

 

[dm9289]

NEC recognized conductors are listed in Table 310.104(A).
It''s double your "weld cable" will be there but it is possible it has a recognized rating also.
Often for flexibility folks will use "DLO" cable which has the recognized "RHW" rating also.
There is, however, a lot involved in VFD cables other than flexibility.

https://www.southwire.com/products/DLODieselLocomotiveCableoem.htm

Thank you im in 310.014 now could not find the double your weld cable but did find the RHW. I have used the DLO did not find it in the code book but I liked it

 

[dm9289]

Welding cable, unless additionally marked at RHW of RHH (or other insulation type found in the NEC) cannot be used for NEC applications. Also note that standard terminations are not suitable for use with finely stranded conductors like this.

Thank you I will make sure. I think I may have found low cost VFD

 

[augie47]

Thank you im in 310.014 now could not find the double your weld cable but did find the RHW. I have used the DLO did not find it in the code book but I liked it

DLO won't be in the NEC as it's not recognized by the NEC but if it carries the added RHW listing it is approved.

 

[Jraef]

And good luck pulling DLO though conduit... It tends to grip the walls, even with lots of lube.

I'd say that at least 75% of the VFD problems I have to deal with are caused by people wanting the benefits of the VFD, but not wanting to take the time and/or spend the money to install them correctly, including the wiring. Read this document before you start. It's not specific to the brand, it's a compilation of valuable information gathered from 30+ years of experience by Reliance and Allen Bradley drive technical support and field service people on how to avoid the most common mistakes. It applies to ALL makes and models of VFDs, no exceptions.

http://literature.rockwellautomation.com/idc/groups/literature/documents/in/drives-in001_-en-p.pdf

 

[dm9289]

Thanks for the info in my case its only a 15 ft pull but good article

 

[dm9289]

DLO won't be in the NEC as it's not recognized by the NEC but if it carries the added RHW listing it is approved.

OK thanks

 

[augie47]

In the day or two I've been around here I've picked up on one point. VFD = listen to Jraef

 

[qcroanoke]

In the day or two I've been around here I've picked up on one point. VFD = listen to Jraef

Ditto!

 

[SceneryDriver]

And good luck pulling DLO though conduit... It tends to grip the walls, even with lots of lube.

I've had to put welding cable / DLO in conduit a couple of times, and hands down the best pulling lube is baby powder. Place the cable and a liberal amount of baby powder in a large garbage bag, and "shake-n-bake." The baby powder removes the "tack" from the cable jacket. Also makes the electrical room smell all clean and fresh, as a bonus.

Using a turkey baster to "puff" some additional baby powder into the conduit helped as well.

Pull was about 20', with almost 360deg of bends. It was actually a very easy pull, all things considered.


rpoet

 

[don_resqcapt19]

I have never tried baby powder or talc to pull conductors.

I did few 1500 and 1750 HP DC motors, that had 700 volt armatures and used 535.3 kcmil DLO for the conductors. Four pulled in 4" rigid conduit about 125-150' long with three 90s. We used Yellow 77 and did not have any issues with the pull.

I did keep some baby powder around for use with rubber voltage rated gloves.

 

[Andy Delle]

What is the voltage rating of welding cable. IIRC, the actual voltage is less than 50 volts.

I ran into a similar problem on large UPS installations. 600v THHN doesn't safely cut it when you have a battery feed of +/- 540v to ground.

We ended up using 500mcm "rail road" cable. The stuff used in the traction electrical system. It is 2kv rated.

 

[don_resqcapt19]

What is the voltage rating of welding cable. IIRC, the actual voltage is less than 50 volts.

Some is rated at 100 volts and other is rated at 600 volts.

I ran into a similar problem on large UPS installations. 600v THHN doesn't safely cut it when you have a battery feed of +/- 540v to ground.

We ended up using 500mcm "rail road" cable. The stuff used in the traction electrical system. It is 2kv rated.

Rail road cable is also known as DLO "Diesel Locomotive" cable. It is available in 1 and 2 kv rated.