I'm working on a project that has 1000KW standby generator. I'm providing 1200A switch board (or I think I could use Power Distribution Board)with main fused switch. The question is, do I have to have the main fused disconect? in another word, does the six disconnect rule applies on the Generator? Thank you in advance
Generator Power Distribution
- Thread starter sam34
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bdarnell
Senior Member
- Location
- Indianapolis, IN
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- Retired Engineer
Re: Generator Power Distribution
I'm not sure I understand the question, but if you are asking what I think you are asking, the generator will have an output breaker on it. If you are feeding a transfer switch that is ahead of your service main, it will need to be a SE rated transfer switch and will most likely have a service disconnect which will be your main disconnecting device.
If this generator is going somewhere else in the power distribution system of the building, then the "six switch" rule doesn't apply.
Hope that answered the question.
I'm not sure I understand the question, but if you are asking what I think you are asking, the generator will have an output breaker on it. If you are feeding a transfer switch that is ahead of your service main, it will need to be a SE rated transfer switch and will most likely have a service disconnect which will be your main disconnecting device.
If this generator is going somewhere else in the power distribution system of the building, then the "six switch" rule doesn't apply.
Hope that answered the question.
Re: Generator Power Distribution
Brad, thanks for replying; does the main output breaker at the generator an option? because the generator will be feeding 1200A MDP panel and from the MDP feeding multiple ATS's . My question was do I have to have the main fuse (MCB) 1200A or I can do MLO if I have less than 6- branch feeders?Also, if I have to have the main, do we sized it based on 125% of the rated amps? lets assume we are using 750KW, do I use 1000A MCB or 1200A? (the generator located inside the building)thanks in advance
Brad, thanks for replying; does the main output breaker at the generator an option? because the generator will be feeding 1200A MDP panel and from the MDP feeding multiple ATS's . My question was do I have to have the main fuse (MCB) 1200A or I can do MLO if I have less than 6- branch feeders?Also, if I have to have the main, do we sized it based on 125% of the rated amps? lets assume we are using 750KW, do I use 1000A MCB or 1200A? (the generator located inside the building)thanks in advance
Re: Generator Power Distribution
One more thing, if I'm using MDP (not a switchboard), is that mean I can't branch off from the MDP to Emergency, stand-by and optional ATS switches (per 700.9(B)). To me, it looks like I have to have (2) output breakers, one dedicated for the emergency load!!! Is this correct. Thanks
One more thing, if I'm using MDP (not a switchboard), is that mean I can't branch off from the MDP to Emergency, stand-by and optional ATS switches (per 700.9(B)). To me, it looks like I have to have (2) output breakers, one dedicated for the emergency load!!! Is this correct. Thanks
bdarnell
Senior Member
- Location
- Indianapolis, IN
- Occupation
- Retired Engineer
Re: Generator Power Distribution
Per 445.18, you need the breaker in the generator and I think that if you are going to have normal and emergency circuits share a generator, they need to be independant breakers and feeders.
I can't say as I have ever designed or installed something like this, so there may be a better way.
Per 445.18, you need the breaker in the generator and I think that if you are going to have normal and emergency circuits share a generator, they need to be independant breakers and feeders.
I can't say as I have ever designed or installed something like this, so there may be a better way.
- Location
- Illinois
- Occupation
- retired electrician
Re: Generator Power Distribution
Sam,
If the generator is not in the building where the MDP is located, then 225.33(A) would apply unless you meet the conditons in 702.11.
Don
Sam,
If the generator is not in the building where the MDP is located, then 225.33(A) would apply unless you meet the conditons in 702.11.
Don
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