Disco at Buck and Boost?

[florida-sparkey]

Hello all,
I am reducing line voltage (247 to 230 volts 1p) for an autoclave at a veterinary office. I do not see that a disco is required at the autotransformer (450.4) or am I incorrect? Aside from the NEC, does OSHA require a disco? The autoclave unit is plug and cord so no issue there 422.33. If no disco is the correct answer, then may I ask why? It seems to me a lock out device in a commercial application is the way to go. (we use 2008 NEC here)
thanks!!

 

[kwired]

450.14 Disconnecting Means.
Transformers, other than Class 2 or Class 3 transformers, shall have a disconnecting means located either in sight of the transformer or in a remote location. Where located in a remote location, the disconnecting means shall be lockable in accordance with 110.25, and its location shall be field marked on the transformer.

I believe this applies to all transformers including an autotransformer (which is what a buck - boost is), with noted exception of class 2 or 3 transformers.

 

[under8ed]

If you mount the transformer within the new equipment, would not the power cord plug suffice as the disconnect?

 

[kwired]

If you mount the transformer within the new equipment, would not the power cord plug suffice as the disconnect?

True, unless you do not want to modify equipment for warranty reasons or something like that.

 

[florida-sparkey]

Thanks for the input. kwired, I do not see 450.14 in my 2008 code. Am I missing it or is that a later cycle?

 

[petersonra]

Hello all,
I am reducing line voltage (247 to 230 volts 1p) for an autoclave at a veterinary office. I do not see that a disco is required at the autotransformer (450.4) or am I incorrect? Aside from the NEC, does OSHA require a disco? The autoclave unit is plug and cord so no issue there 422.33. If no disco is the correct answer, then may I ask why? It seems to me a lock out device in a commercial application is the way to go. (we use 2008 NEC here)
thanks!!

IMO it is a transformer and requires a disconnecting means. As a practical matter this requirement should not be especially onerous. A breaker lockout bracket on the CB supplying power suffices for the disconnecting means required as long as you put a sign at the transformer saying where it is.

ETA: The disconnecting means requirement does not seem to appear in the 2008 version.

 

[kwired]

Thanks for the input. kwired, I do not see 450.14 in my 2008 code. Am I missing it or is that a later cycle?

450.14 was new in 2011 NEC.