Headroom for 400 Amp service

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adavey

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We are planning to install a 400 amp single phase switch feeding 2-200A panel boards in the same room (approx. 300 sq. ft. in size) to accommodate HVAC equipment. The current service is 200 amps single phase for this Historic Structure built in the 1780's.

Currently, we have headroom of 6'2" in the room. The NEC calls for 6'5" of headroom for the 400A upgrade. Do I need to relocate the 400 switch and panelboards to a location that has 6'5" of headroom, or is there a provision in the NEC for me to use ?????????

I don't have the NEC w/ me (left at work), but I think I referenced art. 110.
 
Re: Headroom for 400 Amp service

You need to look at 110.26(E). The 200 amp panels are OK without the 6'6" headroom due to the exception, however the 400 amp switch will need to be moved to an area that provides the minimum 6'6" headroom.
 
Re: Headroom for 400 Amp service

Is the new 400 amp switch replacing the existing 200 amp service? More to the point, will the new 400 amp switch be "service equipment" (i.e., fed directly from the utility)? If the "service" is somewhere else, and if the 400 amp switch is sub-fed from the service, then 110.26(E) would not come into play. There would not be an issue with headroom.
 
Re: Headroom for 400 Amp service

Originally posted by charlie b:
Is the new 400 amp switch replacing the existing 200 amp service? More to the point, will the new 400 amp switch be "service equipment" (i.e., fed directly from the utility)? If the "service" is somewhere else, and if the 400 amp switch is sub-fed from the service, then 110.26(E) would not come into play. There would not be an issue with headroom.
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Why do you say this? :confused:
about service equipment, switchboards, panelboards, or motor control centers shall be 2.0 m (6? ft).
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Re: Headroom for 400 Amp service

Thanks, Mike. I did read that wrong. Mea culpa. :)

Disregard my last transmission. Out.
 
Re: Headroom for 400 Amp service

400 Amp disconnet from meter???

Now that I should locate the 400 Amp panel (3R enclosure)outside; does theservice disconnect a fused or non-fused 400 Amp disconnect ???????

Note: I can't mount switch inside due to it's historic status. I believe my best option is outside.
 
Re: Headroom for 400 Amp service

Are you required to install the 400 amp disconnect?
 
Re: Headroom for 400 Amp service

Originally posted by adavey:
single means of disconnect for 2-200A panelboards.
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What I think Infinity is asking is why do you need a single means of disconect?

Each panel must have OCP and that can be your service disconnects, you are allowed up to six service disconnects.
 
Re: Headroom for 400 Amp service

I don't have the code w/ me, but I thought the incoming service requires a single means of disconnect for all electric ?????
 
Re: Headroom for 400 Amp service

Originally posted by adavey:
I don't have the code w/ me, but I thought the incoming service requires a single means of disconnect for all electric ?????
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The NEC allows up to six (sometimes more) service disconnects.

Many people come out of a 400 amp meter and feed two grouped 200 amp main breaker panels.

No need for the 400 amp disconnect and costs.

230.71 Maximum Number of Disconnects.
(A) General. The service disconnecting means for each service permitted by 230.2, or for each set of service-entrance conductors permitted by 230.40, Exception Nos. 1, 3, 4, or 5, shall consist of not more than six switches or sets of circuit breakers, or a combination of not more than six switches and sets of circuit breakers, mounted in a single enclosure, in a group of separate enclosures, or in or on a switchboard. There shall be no more than six sets of disconnects per service grouped in any one location. For the purpose of this section, disconnecting means used solely for power monitoring equipment, or the control circuit of the ground-fault protection system or power-operable service disconnecting means, installed as part of the listed equipment, shall not be considered a service disconnecting means.
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Re: Headroom for 400 Amp service

Thanks Bob for reading my mind. I was asking if he had some requirement for the 400 amp disconnect. Was it engineered that way or is it a POCO requirement etc.

As Bob said, we typically would come out of the 400 amp CT enclosure with two sets of conductors to feed two 200 main breaker panels, grouped together. This would eliminate the 400 amp disconnect which would save quite a bit of labor and materials, and solve your height issues.


Trevor
 
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