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dgajr 07-17-2010 04:59 PM

Need help sizing Generator cable
 
I could use some help in determining what size conductor I need to make a generator cable. This cable will only be 15' long and will be connecting a PTO generator (150A breaker) to a transfer switch. I would like to use welding cable (more flexible and easier to manage).

What size conductor would the welding cable need to be. It seems to me that welding cable has a higher rated amperage spec than a comparable size THHN...etc. I was planning to use 1/0 THHN, but am unsure that I am reading the tables for the welding cable properly.

Thanks in advance.

David

mpoulton 07-19-2010 05:43 PM

Welding cable ratings are based on low duty-cycle use out in open air, hence the high ratings compared to THHN. THHN ratings are for continuous use enclosed in conduit or walls. If this cable is to be used out in the open, I would probably be comfortable with #2 welding cable for 150A. I've used #4 welding cable for 100A cables like this and it didn't get too hot. That's not an official code-based answer, just an experience-based opinion. The official code-based answer is to not use welding cable for generator hookups.


Quote:

Originally Posted by dgajr (Post 470971)
I could use some help in determining what size conductor I need to make a generator cable. This cable will only be 15' long and will be connecting a PTO generator (150A breaker) to a transfer switch. I would like to use welding cable (more flexible and easier to manage).

What size conductor would the welding cable need to be. It seems to me that welding cable has a higher rated amperage spec than a comparable size THHN...etc. I was planning to use 1/0 THHN, but am unsure that I am reading the tables for the welding cable properly.

Thanks in advance.

David


frenchelectrican 07-20-2010 01:07 AM

Is this generator is single phase or triphase unit ??

And how many KW it have also ?

For 150 amp rated cable you will need at least 55mm˛{ 1/0 AWG } or larger.

Check with the generator dealer sometime they will have proper sized cable to fit your generator and IIRC you should have Anderson plug or Pin and Sleeve connector on it.

The Pin and Sleeve is more expensive but it is very rugged hard to get it destory it

But the Anderson plug is pretty much restricted to single phase useage.

But on triphase verison they do come in either Delta or Wye connection so becarefull with connection at the first time.

The THHN/THWN conductor is not very fexiable at all especally with larger size.

I will not recommend that you use the welding cable due they are only rated to handle secondary voltage not the primary voltage like your normal electrical system is.

Unless you get DLO { Diesel Locomovite } cable they are pretty flexiable but they do come in somehow odd size cables and you may need specail connectors.

Most of the larger generators I installed I used either THHN/THWN or DLO or others as needed.

Merci.
Marc


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