230.91

[donaldsullivan]

Ever asked "How far is immediately adjacent thereto"?
Would inside a locked security gate of a rural water plant with supervised trained personel,witin site, 32' away, meet the intent?

I honestly think that may be stretching it. But it accidentially ended up that way on my job.

Its a 277/480V, 3-phase, outdoor rack with a 400A manual transfer switch as "service disconnect" with portable generator receptacle. Load is #350MCM to a 350AT main circut breaker in a MCC inside adjacent building.

We will either install cable protector fuses in MTS or series switch with fuses. Replace existing MTS with fused switch more $$$.

Any comments please.

 

[ron]

Re: 230.91

So your saying that for 32' downstream from the meter, there is no overcurrent/short circuit protection?
Seems to far to me!
Most jurisdictions say 5' or so is max.

 

[hurk27]

Re: 230.91

I believe if the 350AT main circuit breaker Is close to where the Service entrance cables enter the building then this would be the service disconnect/OCPD for that building.
I don't think a transfer switch is allow on the supply side of the service disconnect. and to use it as the service disconnect most transfer switch's I have seen would violate 230.77.

I think there should be a service disconnect ahead of the MTS on the utility side of it and it has to have OCPD's rated for the load. The generator side can be protected by the OPCDs on the generator. I have done many lift stations that use a similar set up but we always have a disconnect next to the meter then to the transfer switch.

Maybe some others will chime in here?

 

[iwire]

Re: 230.91

I do not fully understand the setup as described.

In order for the MTS to serve as the service disconnect it would have to be service rated.

I have found not all service rated transfer switches have integral overcurrent protection which would mean we would need to add OCP 'immediately adjacent thereto'.

In my humble opinion 'immediately adjacent thereto' would mean as close as physically possible. Just a short nipple between enclosures, any measurement that includes 'feet' IMO would be to far to be considered immediately adjacent.

IMO the term 'immediately adjacent' is a stricter command then the usual 'grouped' term used with disconnects.

JMO, Only your inspector knows for sure.

[ April 08, 2005, 07:55 PM: Message edited by: iwire ]

 

[hurk27]

Re: 230.91

But Bob wouldn't it violate 230.77? Unless it has a center position for Off?
O DUH!!

 

[iwire]

Re: 230.91

A small part of "TRANSFER SWITCHES (WPTZ) UK" from the UL GENERAL INFORMATION DIRECTORY 2004

Transfer switches rated 600 volts and less which have been investigated for their suitability for use as service equipment are marked, ??SUITABLE FOR USE AS SERVICE EQUIPMENT.??

Transfer switches are required to be designed so that the load can not remain simultaneously disconnected from both the normal and alternative sources when either or both sources are available, except that transfer switches marked, ??SUITABLE FOR USE AS SERVICE EQUIPMENT?? are provided with accessible means to independently disconnect both the normal and alternate sources.