Transfer switch as main disconnect

[GerryB]

I'm hoping someone can reply to this. It is not about bonding. I installed a manuel 200 amp transfer switch for a customer for their generator. (portable) I mounted it adjacent to the 200 amp panel, took the SEU out of the panel and fed the top line side of the tranfer switch and re-fed the 200 amp main from the center load position of the transfer switch. The local utility company has one paragraph in their guideline book about generators. It states "Such installations require an adequately sized double throw or open transition switch. The switch must be on the load side of the main disconnect switch and metering equipment. The switch must disconnect the Company's lines from the Customer's wiring before the generator can be connected to supply electricity." They are saying they want the main breaker before the transfer switch. The only way to do that is change the meter outside to a meter with the 200 amp breaker in. I thought and one local electrical inspector agreed that the tranfer switch becomes the main disconnect and the panel then is a sub-panel. The tranfer switch is service rated equipment. Nothing at all changes from the utilty company point of view as I can see. The SEU is still hot from the meter to first disconnect point.(only 3 or 4 feet) Any replys?

 

[Little Bill]

I'm hoping someone can reply to this. It is not about bonding. I installed a manuel 200 amp transfer switch for a customer for their generator. (portable) I mounted it adjacent to the 200 amp panel, took the SEU out of the panel and fed the top line side of the tranfer switch and re-fed the 200 amp main from the center load position of the transfer switch. The local utility company has one paragraph in their guideline book about generators. It states "Such installations require an adequately sized double throw or open transition switch. The switch must be on the load side of the main disconnect switch and metering equipment. The switch must disconnect the Company's lines from the Customer's wiring before the generator can be connected to supply electricity." They are saying they want the main breaker before the transfer switch. The only way to do that is change the meter outside to a meter with the 200 amp breaker in. I thought and one local electrical inspector agreed that the tranfer switch becomes the main disconnect and the panel then is a sub-panel. The tranfer switch is service rated equipment. Nothing at all changes from the utilty company point of view as I can see. The SEU is still hot from the meter to first disconnect point.(only 3 or 4 feet) Any replys?

If the transfer switch is "service rated", then it becomes your main and the original main is now a sub panel.

 

[qcroanoke]

If the transfer switch is "service rated", then it becomes your main and the original main is now a sub panel.

I hope so, Cause that is exactly what I did in my home.

 

[hurk27]

For a transfer switch to be service rated it has to have OCPD in it, and as said it becomes your service disconnect.

No OCPD's no service rated
although I have seen some transfer switch's state service rated without OCPD, but they would not be in compliance with the NEC.

 

[jumper]

For a transfer switch to be service rated it has to have OCPD in it, and as said it becomes your service disconnect.

No OCPD's no service rated
although I have seen some transfer switch's state service rated without OCPD, but they would not be in compliance with the NEC.

Are you sure?

230.79 says this:

230.79 Rating of Service Disconnecting Means. The service
disconnecting means shall have a rating not less than
the calculated load to be carried, determined in accordance
with Part III, IV, or V of Article 220, as applicable. In no
case shall the rating be lower than specified in 230.79(A),
(B), (C), or (D).

and 230.91 this:

230.91 Location. The service overcurrent device shall be
an integral part of the service disconnecting means or shall
be located immediately adjacent thereto.

So why wouldn't a service rated transfer switch with out an OCPD, but next to a main panel with a MCB not be legal?

 

[hurk27]

Are you sure?

230.79 says this:

230.79 Rating of Service Disconnecting Means. The service
disconnecting means shall have a rating not less than
the calculated load to be carried, determined in accordance
with Part III, IV, or V of Article 220, as applicable. In no
case shall the rating be lower than specified in 230.79(A),
(B), (C), or (D).

and 230.91 this:

230.91 Location. The service overcurrent device shall be
an integral part of the service disconnecting means or shall
be located immediately adjacent thereto.

So why wouldn't a service rated transfer switch with out an OCPD, but next to a main panel with a MCB not be legal?

You know back a few years ago this came up, and I argued that transfer switch's that were service rated had to be protected from over load, I never looked any further and assumed it was a UL thing (as I think this was mentioned) but the consensus was it had to be ahead of the transfer switch as the transfer switch required a means of disconnect?

Maybe Bob or someone from those days will chime in on this as I can't seem to remember just what it was?

 

[ceb58]

You ask this same question in G&B.
If it doesn't have OC protection then the rules Jumper posted apply. But as you stated it is the POCO that has a problem with the install.

The local utility company has one paragraph in their guideline book about generators. It states "Such installations require an adequately sized double throw or open transition switch. The switch must be on the load side of the main disconnect switch and metering equipment

They are saying they want the main breaker before the transfer switch

The POCO can come up with their own rules. If this were a service rated ATS then you would be good. It would then comply with the NEC and the POCO's rules.

 

[texie]

IMHO this would be NEC compliant IF the manual transfer switch is SUSE rated (they are available) and the grounding and bonding is correct. If it was an automatic xfer switch, it would be a different story as I don't think they are made with a SUSE rating without disconnect/OCPD.
But the POCO may rule here, as it's their call on the line side.

 

[jwelectric]

In order to comply with UL Standards the transfer must have an absolute off where the utility and generator both can be off at the same time in order to be rated as service equipment. All bonding must take place in the transfer switch also.