Height of main disconnect in switchboard

[pisani168]

My understanding is that the max height of the operable part of a disconnect shall not be higher than 6’-7” or 79”. I have a couple of approval drawing in front of me for switchboards with a height of 90“ Their disconnect handle is at 82” of height. IMO the disconnect needs to be lowered on the dead front to be accessible or am I missing something?

 

[augie47]

A 4" high "work platform" on the floor in front of the switchboard is one solution

 

[qcroanoke]

A 4" high "work platform" on the floor in front of the switchboard is one solution

But why would that build such a beast if they know the handle height is too high?

 

[augie47]

That's a good question

 

[petersonra]

My understanding is that the max height of the operable part of a disconnect shall not be higher than 6’-7” or 79”. I have a couple of approval drawing in front of me for switchboards with a height of 90“ Their disconnect handle is at 82” of height. IMO the disconnect needs to be lowered on the dead front to be accessible or am I missing something?

You might be missing something.

240.24 Location in or on Premises.
(A) Accessibility. Switches containing fuses and circuit breakers
shall be readily accessible and installed so that the center of
the grip of the operating handle of the switch or circuit
breaker, when in its highest position, is not more than 2.0 m
(6 ft 7 in.) above the floor or working platform, unless one of
the following applies:
(1) For busways, as provided in 368.17(C).
(2) For supplementary overcurrent protection, as described
in 240.10.
(3) For overcurrent devices, as described in 225.40 and
230.92.

I am not sure where you are measuring the 82 " at either. Note where the 6' 7" is supposed to be measured from. It is not from the top of the handle in the ON position.

 

[qcroanoke]

You might be missing something.


I am not sure where you are measuring the 82 " at either. Note where the 6' 7" is supposed to be measured from. It is not from the top of the handle in the ON position.

But it does say from the center of the grip in its highest position.Which could be the on position.

 

[petersonra]

But it does say from the center of the grip in its highest position.Which could be the on position.

you have a point?

 

[qcroanoke]

you have a point?

I think I made it.

 

[Carultch]

But it does say from the center of the grip in its highest position.Which could be the on position.

Not only could it be the ON-position, it would HAVE to be the ON-position. The NEC requires that vertically-operated switches and breakers to have the ON-position oriented upward, and the OFF-position downward. This is required in order for the fail-safe operation to be in the direction of gravity, and so that it matches a user's intuition.

The two exceptions I can think of, are traveling switches where the relation of up/down to on/off will vary with user behavior, and double throw (aka transfer) switches, where there is an ON-position on both sides of the OFF-position.

 

[Jraef]

I don't think Bob's point was whether the switch was in the ON position or not, of course it would be in the ON position. The point was that the 6'7" is not measured to the top of the handle, it is measured to the CENTER of the handle.

In old Allen Bradley MCCs, the TOP of the disconnect handle on a 1 space factor starter or breaker was 1/2" more than 6"7" off of the ground if you added the mounting sills to the MCC. Technically this was OK because of that wording because the CENTER of the handle was less than 6'7", but there were some inspectors who would not abide by that. So they gave away a little drop-down handle that clipped onto the disconnect handle to meet the requirement. I probably still have a few of those clips floating around in a tool box somewhere. It was easier to just put the clip on than to argue with the AHJ... I think they must have redesigned the MCC handles though, because I couldn't find even a reference to that clip in the current literature.

 

[jim dungar]

In old Allen Bradley MCCs, the TOP of the disconnect handle on a 1 space factor starter or breaker was 1/2" more than 6"7" off of the ground if you added the mounting sills to the MCC. Technically this was OK because of that wording because the CENTER of the handle was less than 6'7", but there were some inspectors who would not abide by that. So they gave away a little drop-down handle that clipped onto the disconnect handle to meet the requirement.

The old Square D Model 4 MCC was the same way.