generator transfer switches

[andy74bronco]

Hi i am pretty sure I know the answer but I would like some verification on this subject. I am looking at a large generator transfer switch job. The service is 600 amp three phase 120/208. When a transfer switch is installed in front of the main breaker/breakers does the bonding needs to be moved and the new main breaker is now in the transfer switch? Then the transfer switch needs to be service entrance rated and also have a breaker? It is a big job and just in bidding stage. The load is not that big which is not related to this question just back ground information. I called the power company and the largest load last year in September was 27kw. Thanks for your help. I am guessing a small residential situation would be the same with a whole house transfer switch.

 

[HackElectric]

Yes, the TS becomes the first means of disconnect so the bonding needs to be done there and the GEC/s need to be moved there. As you mentioned, the TS needs to be SUSE.

The existing equipment that used to be the service disconnect needs to have the n-g bond removed. Sometimes this can be a pain if many EGC's are terminated to the same bar as the neutrals.

 

[gadfly56]

Yes, the TS becomes the first means of disconnect so the bonding needs to be done there and the GEC/s need to be moved there. As you mentioned, the TS needs to be SUSE.

The existing equipment that used to be the service disconnect needs to have the n-g bond removed. Sometimes this can be a pain if many EGC's are terminated to the same bar as the neutrals.

Which is a good argument for putting separate ground and neutral bars in the panel with a tie between them, just in case. More and more people seem to want generators installed for resi not to mention commercial service.

 

[ActionDave]

Which is a good argument for putting separate ground and neutral bars in the panel with a tie between them, just in case. More and more people seem to want generators installed for resi not to mention commercial service.

Easier just to put the transfer switch after the Service Disconnect.

 

[qcroanoke]

Easier just to put the transfer switch after the Service Disconnect.

If there is one. OP indicated "main breaker/breakers"
I would look at service disconnect to ATS to panel if I there is room.
Isn't a service rated ATS pricey?

 

[HackElectric]

Which is a good argument for putting separate ground and neutral bars in the panel with a tie between them, just in case. More and more people seem to want generators installed for resi not to mention commercial service.

I agree 100%.

When doing service upgrades I always leave the top spaces open for an Interlock so the customer can have a portable generator connection installed easily later and I also separate the grounds and neutrals as you said. Of course, I point these things out to the customer and give them my generator flier to think over their options :thumbsup:

 

[gadfly56]

Easier just to put the transfer switch after the Service Disconnect.

Here in NJ the panel is almost always the only Service Disconnect, certainly for resi service.

 

[ceb58]

If there is one. OP indicated "main breaker/breakers"
I would look at service disconnect to ATS to panel if I there is room.
Isn't a service rated ATS pricey?

I agree, a decision will need to be made based on space and price. A main disconnect before the ATS or a 600 amp SE rated ATS