300 kW generator 480 volt w/ 600-amp breaker...2-sets of 4/0 wire

[mallard duck]

I have a project to install a 480 volt, 250/500 kW UPS between the transfer switch and the 600-amp MDP. The problem I found is the wiring from the 600-amp 100% rated GE breaker Spectra SGHA36AT0600 at the switchgear is feeding the ATS with 2 sets of 4/0. Between the 300 kW generator's 600-amp breaker is the same 2-sets of 4/0 and between the ATS and the MDP is the same.

Can someone tell me I am wrong to think all this wire and 2 inch conduit will need to be replaced with 300 KCM in 2-1/2" conduit.

 

[augie47]

Depending on your calculated load, a 250 kmil might be adeqaute, but not 4/0s

 

[mallard duck]

I am going to hate breaking the news to the customer as the generator was only put in a couple years back. Saw no. 1 THHN wire in 1-1/2" conduit on the 225-amp breaker in the MDP also, feeds a sub-panel. He will be spending more money on corrections. This generator already feeds a large computer room along with the HVAC units for that area.

 

[cal40]

wiring methods once inside a generator enclosure

wiring methods once inside a generator enclosure

I'm wondering once inside the genrator enclosure . Can we free-air from our pipes stubbed up out of slab (inside enclosure) to our disconnect switch . We have (2) sets of 600 mcm not much room for any 4" seal tight or greenfield connections or terminations . The generator is a 500KW deisel , double walled tank , above ground . The inspectors asking for it be in seal tight to protect it from the elements (we are inside the enclosure already) . Any thoughts ??

 

[augie47]

are you asking about conductors inside the generator cabinet ?

 

[cal40]

Wiring Methods inside generator cabinets

Wiring Methods inside generator cabinets

I'm wondering once inside the genrator enclosure . Can we free-air from our pipes stubbed up out of slab (inside enclosure) to our disconnect switch . We have (2) sets of 600 mcm not much room for any 4" seal tight or greenfield connections or terminations . The generator is a 500KW deisel , double walled tank , above ground . The inspectors asking for it be in seal tight to protect it from the elements (we are inside the enclosure already) . Any thoughts ??

.

 

[GearMan]

I have a project to install a 480 volt, 250/500 kW UPS between the transfer switch and the 600-amp MDP. The problem I found is the wiring from the 600-amp 100% rated GE breaker Spectra SGHA36AT0600 at the switchgear is feeding the ATS with 2 sets of 4/0. Between the 300 kW generator's 600-amp breaker is the same 2-sets of 4/0 and between the ATS and the MDP is the same.

Can someone tell me I am wrong to think all this wire and 2 inch conduit will need to be replaced with 300 KCM in 2-1/2" conduit.

I find it odd that the main line breaker for the generator is 600A, seems high. Also, is the rating plug in the SGHA breaker full 600A? If it was a 400A chip (SRPG600A400) and 400A gen cb, this would make more sense. Just having a hard time thinking the wrong wire size would not have been caught. What is the rating on the ATS? Just a thought.

 

[GearMan]

I am going to hate breaking the news to the customer as the generator was only put in a couple years back. Saw no. 1 THHN wire in 1-1/2" conduit on the 225-amp breaker in the MDP also, feeds a sub-panel. He will be spending more money on corrections. This generator already feeds a large computer room along with the HVAC units for that area.

Check the rating plug on this breaker. Probably a Spectra with a lower amp plug.

 

[ActionDave]

I'm wondering once inside the genrator enclosure . Can we free-air from our pipes stubbed up out of slab (inside enclosure) to our disconnect switch . We have (2) sets of 600 mcm not much room for any 4" seal tight or greenfield connections or terminations . The generator is a 500KW deisel , double walled tank , above ground . The inspectors asking for it be in seal tight to protect it from the elements (we are inside the enclosure already) . Any thoughts ??

Welcome to the forum. Sorry for any ambiguity but the short answer is, "Yes" and, "It depends."

What kind of generartor? How is it to be used?

 

[ron]

I find it odd that the main line breaker for the generator is 600A, seems high. Also, is the rating plug in the SGHA breaker full 600A? If it was a 400A chip (SRPG600A400) and 400A gen cb, this would make more sense. Just having a hard time thinking the wrong wire size would not have been caught. What is the rating on the ATS? Just a thought.

Good point. Also check if there adjustments on the trip unit for long time pickup, which will further adjust a trip plug/sensor.