800 amp, Right?

[ptonsparky]

My bedside copy of the NEC happens to be'08.

Dairy customer with an 800 amp 480v generator that went TU. Oil in the water. They use it for load shedding and standby. Salesman called today confirming the crane will be onsite to remove old and set new and informs me that the install might be a bit more involved than discussed. I'll need some extra wire. He has the splices.

That was an 800, right?

Yes. The new one is 1200. Well turn the setting down, though.

I see this set up as needing GFP plus somewhat larger than two 500s per phase.

Yes?

 

[templdl]

My bedside copy of the NEC happens to be'08.

Dairy customer with an 800 amp 480v generator that went TU. Oil in the water. They use it for load shedding and standby. Salesman called today confirming the crane will be onsite to remove old and set new and informs me that the install might be a bit more involved than discussed. I'll need some extra wire. He has the splices.

That was an 800, right?

Yes. The new one is 1200. Well turn the setting down, though.

I see this set up as needing GFP plus somewhat larger than two 500s per phase.

Yes?

Does the application actually need 1200A? Why did they opt for a 1200a genset as a replacement? If not then use the existing installation protected for 800a. Just because the genset has the capacity of 1200a doesn't mean that you have to use it.
If the extra capacity is required at a later date then address it at that time.

 

[gk351]

I assume the line side of that feed has some sort of protection besides the generator CB. (disco, MDP, etc) if that is protected to 800A, wouldnt that cover you? Come to think of it, shouldnt wire size be 600Cu parallel since the service is 800A? I thought 800A and larger required parallel conductors to be rated at full amperage capacity, therefore no rounding up to next larger size like with 500 Kcmil. I cant find the reference, but i may be very wrong!

 

[Cow]

800 amps and less can be rounded up.

240.4(B)

Parallel 500's are used all the time over here for 800 amp services.

 

[infinity]

What does the generator feed, a switchboard?

 

[ptonsparky]

What does the generator feed, a switchboard?

It does feed a single disconnect that has a "keyed interlock" with the service disconnect. The term escapes me at the moment.

Kirk key.

 

[augie47]

Just to make sure, you are speaking of a 480/277 system, correct ?

 

[ptonsparky]

Just to make sure, you are speaking of a 480/277 system, correct ?

yes

 

[kwired]

Ground fault protection not needed if you leave your existing 800 amp disconnect in place.

The feeder from the generator to your existing 800 amp disconnect very well may need GFP. Is there overcurrent protection included with the generator, or will you be installing 800 amp device, or is the 800 amp device you are referring to the first overcurrent device in this circuit?

 

[ptonsparky]

Ground fault protection not needed if you leave your existing 800 amp disconnect in place.

The feeder from the generator to your existing 800 amp disconnect very well may need GFP. Is there overcurrent protection included with the generator, or will you be installing 800 amp device, or is the 800 amp device you are referring to the first overcurrent device in this circuit?

I will know in about 38 minutes....if i get gone in time.

 

[ptonsparky]

The genset has a 1200 amp breaker, no GFP. It is what it is.

 

[augie47]

Any chance of changing the rating plug ?

 

[ptonsparky]

Any chance of changing the rating plug ?

Did not look like it, although I must admit I was more concerned with the damage done to the existing pvc risers and conductors when they removed the old genset, then the details of the CB.

Now if I can just find some 4" Flex and connectors.
Found the flex in KC (I just happen to be there), connectors in Denver. Maybe. Nothing like living in a small town.

 

[cowboyjwc]

I would assume that they put in the 1200 because it was faster than trying to find an 800 at the time. You could always just change the breaker in the gen set to 800, couldn't you?