Disconnect voltage rating

[hhsting]

Which section says disconnect voltage rating have to be greater than system voltage? I have 277V single phase mechanical equipment 20A. The toggle switch voltage rating must be greater than 277V but cannot find in NEC 2017.

 

[augie47]

If it's listed and/or labeled for a certain voltage then 110.3(B) should suffice.

 

[d0nut]

110.4.

 

[don_resqcapt19]

Which section says disconnect voltage rating have to be greater than system voltage? I have 277V single phase mechanical equipment 20A. The toggle switch voltage rating must be greater than 277V but cannot find in NEC 2017.

There is no requirement for the disconnect to have a voltage rating that is greater than the system voltage. It must have a rating at least equal to the system voltage.
There are toggle switches rated for 277 volts that are suitable for the disconnect for that equipment

 

[hhsting]

There is no requirement for the disconnect to have a voltage rating that is greater than the system voltage. It must have a rating at least equal to the system voltage.
There are toggle switches rated for 277 volts that are suitable for the disconnect for that equipment

Where is that requirement?

 

[Dsg319]

Where is that requirement?

Why have a 277v UL listed switch if it’s not suitable for use on 277v system voltage?.

I believe your thinking of voltage equal to or greater.

 

[hhsting]

Why have a 277v UL listed switch if it’s not suitable for use on 277v system voltage?.

I believe your thinking of voltage equal to or greater.

Im thinking of equal to basically where is that nec 2017?

 

[Dsg319]

Im thinking of equal to basically where is that nec 2017?

 

[Carultch]

It only needs to be equal or greater. It doesn't need to be greater.

You also don't need to think about the fact that it could vary up to 290V if voltage tends to be high at your location, or the fact that 277V nominal is really 392V instantaneous. If a switch is rated for 277V, it is rated for use on any circuit that is 277V nominal, such that it can withstand the full ANSI standard tolerance that comes with that number.

It also is important that the applicable type of current (i.e. AC or DC) is acceptable within the product rating. Not usually an issue for AC, as most switches are built with AC in mind in the first place. But for DC, this can be very significant, because DC switches have additional safety issues to that govern the product design.

 

[lordofthisworld]

Which section says disconnect voltage rating have to be greater than system voltage? I have 277V single phase mechanical equipment 20A. The toggle switch voltage rating must be greater than 277V but cannot find in NEC 2017.

A single pole toggle switch rated for 277V would suffice as a disconnect means.