Sizing portable generator breaker and wire.

[Nutmegger]

At the moment we are looking to install a Reliance TWB2006DR panel (to replace an existing 200A disconnect), which provides an interlock between the 200A utility main and a 60A generator breaker.
The customer is looking to have an L14-30R box installed for their current genny.
So, to "supply" that L14-30 inlet, are we OK to size the wire between the inlet and the breaker to 60A (6 AWG) and to use that 60A breaker? I know that Reliance makes the 200/30A interlock panel but it would be good to have some room for expansion.
Whether this is OK or not (using a 60A breaker and wire for a 30-amp inlet), what is the code rererence?

 

[ramsy]

At the moment we are looking to install a Reliance TWB2006DR panel (to replace an existing 200A disconnect), which provides an interlock between the 200A utility main and a 60A generator breaker.
The customer is looking to have an L14-30R box installed for their current genny.
So, to "supply" that L14-30 inlet, are we OK to size the wire between the inlet and the breaker to 60A (6 AWG) and to use that 60A breaker? I know that Reliance makes the 200/30A interlock panel but it would be good to have some room for expansion.
Whether this is OK or not (using a 60A breaker and wire for a 30-amp inlet), what is the code rererence?

If your local code adopts NFPA-70, the section for wire size is 445.13(A)

If listed instructions for L14-30R won't allow => 30A, or accept 60A wire, the section is 110.3(B)

 

[suemarkp]

If the generator has internal overcurrent protection and a built in L14-30 receptacle, I don't see how 445.13(A) applies. You'd just use a 30A rated cord from generator to inlet. At the inlet, you can go larger than #10 if you want, but I'm not so sure the L14-30 inlet screws will take anything larger than a #10 or maybe a #8. I think #6 would be impossible, and the inlet box may not be large enough for box fill depending on what it was designed to accommodate.

My generator has a 50A receptacle and so I used a 50A inlet. #6 wire works for that, although it landed in a 60A breaker on the transfer switch. That doesn't really matter, as the protection of the conductors from inlet to transfer switch is done via the generator overcurrent device (50A)and not the size of the breaker in the transfer switch.

 

[infinity]

I have a 50 amp inlet with #8 MC cable between it and the 50 amp CB at the panel. The generator has a L14-30 receptacle so I use a cord with a molded L14-30 cord cap and a 50 amp on the other end. I'm not sure that the back-fed OCPD at the panel is addressed directly by the NEC.