Please comment on the following design issues released to bid.A water plant has a existing 400A overhead service to a disconnect inside the building. They want to install a new generator outside the building approx. 60' from the building. The designer wants to install a new transfer switch inside the building and reroute the present overhead drop directly into the transfer switch.There is no overcurrent protection from the old transfomer bank which is an overhead structure mount to the transfer switch and then on to the original disconnect switch which is approx.10 to 15' from the transfer switch.We questioned this from a service issue.The transfer switch is not service entrance rated. There is no overcurrent protection at the transfer switch. etc.The first overcurrent device is the original 400A disconnect that is now the load off the tranfer switch.When these issues were questioned we were responded to saying they did not interpret these quoted code sections the same way.Am I missing something here. This is an automatic transfer switch with no ability to disconnect the incoming normal power. The service entrance feeders will run approx.15' inside the building before any overcurrent protection is applied. At present there is no ground in the existing 400A switch and no call to install a new one at the time the service is modifed. Help me understand how this could be allowed.
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Design issues with service additions
- Thread starter mf
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Re: Design issues with service additions
This doesn't sound right. The transfer switch needs to be rated as service entrance equip. Also, you'd have to do your G-N bond in there , and remove the old one from the existing switch.
Why not leave the service going into the disconnect, and take the load side of that in to the transfer switch. You'll have the 400A switch to service the transfer switch, and the generator can be turned off by its breaker. Another option is to get an all in one transfer switch/main breaker unit. I know ASCO makes them, pretty slick setup, breakers and everything are included. Probably not much more money.
Here's more info: http://www.asco.com/Products/ATS/series300se/300secat.html
This doesn't sound right. The transfer switch needs to be rated as service entrance equip. Also, you'd have to do your G-N bond in there , and remove the old one from the existing switch.
Why not leave the service going into the disconnect, and take the load side of that in to the transfer switch. You'll have the 400A switch to service the transfer switch, and the generator can be turned off by its breaker. Another option is to get an all in one transfer switch/main breaker unit. I know ASCO makes them, pretty slick setup, breakers and everything are included. Probably not much more money.
Here's more info: http://www.asco.com/Products/ATS/series300se/300secat.html
iggy2
Senior Member
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- NEw England
Re: Design issues with service additions
Your questions appear to be correct. 230.70 requires a service disconnecting means (not overcurrent protection, but read on...) either outside the building or nearest the point of entrance of the SE conductors. 230.90 etc. then requires overcurrent protection integral with or immediately adjacent to the disconnecting means.
Can the transfer switch be manually operated? Even if yes, I don't know too many ATS' that can be manually operated w/o opening the door; also don't know too many inspectors who would accept 15' away as being immedialetly adjacent thereto, nor having to open the door to operate a manual operator on an ATS.
However - is the new ATS inside the building, or at the genset. If at the genset, then whole picture changes....
Might be best to ask your questions again, and if the same answer walk away from this one, sounds like trouble.
Your questions appear to be correct. 230.70 requires a service disconnecting means (not overcurrent protection, but read on...) either outside the building or nearest the point of entrance of the SE conductors. 230.90 etc. then requires overcurrent protection integral with or immediately adjacent to the disconnecting means.
Can the transfer switch be manually operated? Even if yes, I don't know too many ATS' that can be manually operated w/o opening the door; also don't know too many inspectors who would accept 15' away as being immedialetly adjacent thereto, nor having to open the door to operate a manual operator on an ATS.
However - is the new ATS inside the building, or at the genset. If at the genset, then whole picture changes....
Might be best to ask your questions again, and if the same answer walk away from this one, sounds like trouble.
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