Two pole 480v lighting switched from double pole switch

[frankgi]

Hello. Wondering if a two pole, 480 v lighting load can be switched from a double pole switch, rated 277v. I say it can, because 277v is going THRU the switch although 480 volts is present AT the switch. I had someone disagree with me on this. Any thoughts? Thank you.

 

[iwire]

Hello. Wondering if a two pole, 480 v lighting load can be switched from a double pole switch, rated 277v. I say it can, because 277v is going THRU the switch although 480 volts is present AT the switch. I had someone disagree with me on this. Any thoughts? Thank you.

You are applying 480 to the switch, it will have to be rated at least 480 volts.

Where are you finding a 277 volt rated double pole?

 

[frankgi]

Leviton 1222-2 Double-Pole Toggle Switch, 20A, 120/277V, Brown, Industrial Grade

 

[frankgi]

Leviton 1222-2 Double-Pole Toggle Switch, 20A, 120/277V, Brown, Industrial Grade

If it has a UL approval how would they expect to use it, if in fact you were switching two 277v loads??

 

[iwire]

If it has a UL approval how would they expect to use it, if in fact you were switching two 277v loads??

I don't believe you can legally switch two separate 277 volt circuits with it or a single 480 volt circuit.

You could use it for a single 240 or 208 circuit.

 

[frankgi]

I was thinking it would not allow you to use 347v (Canada) thru the switch. Thanks for the reply.

 

[fmtjfw]

347V switches won't fit in a standard box they require a longer mounting screw spacing. This helps prevent lower voltage switches from being used for higher voltages.

 

[kwired]

Many motor rated switches however are rated for up to 600 volts in both two and three pole versions.

They also come with a higher price tag.

 

[frankgi]

347V switches won't fit in a standard box they require a longer mounting screw spacing. This helps prevent lower voltage switches from being used for higher voltages.

Good info. Thank you. Still wondering about this. If the 480 volt load is fed from a double pole breaker (not two single pole breakers) which allows the two 277v's to be de energized simultaneously. Single pole switches are rated for 277v and switch single 277v circuits.

 

[frankgi]

I will just see it as the total load 480v. Switch is not rated for that. Thanks again.

 

[Smart $]

I will just see it as the total load 480v. Switch is not rated for that. Thanks again.

The way to see it is circuit voltage. You can use it in a 277V, 2-, 3-, or 4-wire circuit. You cannot use it in a 480V circuit.

 

[hurk27]

The voltage rating is the voltage that the contacts has to interrupt, on a 277 volt load you will have 277 volts across the contacts when the switch is opened, if you put the switch on a 480 volt load then it will have 480 volt across the contacts, this could cause the tips to arc longer when they are opened under load, this is why most 480 volt lighting loads are switched by the breaker instead, finding a 480 volt rated switch will be a chore,but like was said double pole motor switches are rated for 600 volts but they will have a thermal overload you might have to also purchase, don't think I have ever seen a motor rated switch without the overload, also they are quit large about the size of a GFCI receptacle, you could use a contactor with a lower voltage coil to switch the lights?

It is rare to have HID lighting on switch's because of the delay of them coming on, this can also put people in danger if someone hit the switch while dangerous work is being performed but code allows it.

Also if the lighting circuit is fed from a delta source that has a voltage that exceeds 277 volts to ground there are restrictions to where the lights can be installed and how high they have to be, they are only allowed outdoors on poles at or above 22' or in tunnels at or above 18', they are not allowed indoors, also they can not be plug and cord connected see 210.6(D) (1,2)

 

[petersonra]

I don't see why you could not switch two 277V L-N loads with it. However, if you did that it might have 480V between two adjacent terminals and there are some special requirements for that IIRC.

So, I think the two 277V loads might have to be on the same phase.

 

[Smart $]

I don't see why you could not switch two 277V L-N loads with it. However, if you did that it might have 480V between two adjacent terminals and there are some special requirements for that IIRC.

So, I think the two 277V loads might have to be on the same phase.

Different phases on same device, no problem. The rule is over 300 volts between adjacent devices must have barriers between them [404.8(B)].

 

[kwired]

...don't think I have ever seen a motor rated switch without the overload, also they are quit large about the size of a GFCI receptacle, you could use a contactor with a lower voltage coil to switch the lights?

It is rare to have HID lighting on switch's because of the delay of them coming on, this can also put people in danger if someone hit the switch while dangerous work is being performed but code allows it.

Those switches without overloads are not that uncommon, I use them all the time as a local disconnect in the vicinity of motor when the controller and branch circuit device are not within sight of the motor. They sometimes are even larger body then a GFCI so you need to watch the size of your box if installing the box before you have seen the switch, or you will have trouble pushing things into the box when finishing up.

I don't see why you could not switch two 277V L-N loads with it. However, if you did that it might have 480V between two adjacent terminals and there are some special requirements for that IIRC.

So, I think the two 277V loads might have to be on the same phase.

Biggest issue with NEC is you can't have more then 250 volts between adjacent switches in a typical device box. This rule doesn't apply to a single switch in a box.

Whether a typical 277 volt 2 pole switch can be used for switching a 480 volt load IMO is not a direct NEC rule but rather a listing issue with the switch. However my guess is that none are listed for this. Switching two 277 volt loads with 480 volts between conductors on the switch, is another possible scenario - but again is more of a listing issue then a straight NEC issue. Again I would guess none are listed to have more then 277 volts between any two terminals of the switch. The motor rated switches are designed a little differently and is likely part of reason they are usually marked with 600 volts instead of 277 volts.

 

[hurk27]

I don't see why you could not switch two 277V L-N loads with it. However, if you did that it might have 480V between two adjacent terminals and there are some special requirements for that IIRC.

So, I think the two 277V loads might have to be on the same phase.

There is no restriction on switching a 277 volt load with a 277 volt rated switch, like I said it is the voltage that will be interrupted by the contacts when opened that the rating is for.

You raise an interesting point, for two separate switch's we can use a barrier between the two switch's when the voltage exceeds 300 volts, but how can we do this with a double pole??? maybe it wouldn't apply since it is a double pole?:?

 

[hurk27]

So, I think the two 277V loads might have to be on the same phase.

I got to back up a little, someone also thought of this problem as 404.8(C) clearly doesn't allow it:

(C) Multipole Snap Switches. A multipole, general-use
snap switch shall not be permitted to be fed from more than
a single circuit unless it is listed and marked as a two-circuit
or three-circuit switch, or unless its voltage rating is not less
than the nominal line-to-line voltage of the system supplying
the circuits.

wonder if they are listed as a two circuit device??

 

[kwired]

I got to back up a little, someone also thought of this problem as 404.8(C) clearly doesn't allow it:



wonder if they are listed as a two circuit device??

I think, what they are after with the "two circuit" device is that you can not put (and a more common application may be with 120 volt circuits) a load of a individual circuit on one pole of the switch, and the load of a completely separate circuit on the other pole - and have them commonly switched by the two pole switch. But if you were to have two 120 volt loads on different legs of a multiwire branch circuit this is still one circuit. It works with 120 volt loads with 120-277 volt rated switches because there is not more then 277 volts between any point on the switch body. It does not work with 277 volt loads because you have 480 volts on the switch body and the switch is only rated for 277 volts. Go to a 600 volt rated "motor switch" and you are fine though. I doubt most of your typical 277 volt rated wall switches are listed for more then one circuit. But they work great for 240 and 120/240 volt circuits.

JMO though, shoot holes in it if you find something wrong with it.

 

[mgookin]

When voltage and current ratings are assigned to an electrical device the current rating is based on the cross section of the copper carrying the current and the voltage rating is based on the distance between conductors to prevent arcing.

They're telling you that device is not suitable to prevent arcing between conductors at anything greater than 277VAC.

 

[Rampage_Rick]

347V switches won't fit in a standard box they require a longer mounting screw spacing. This helps prevent lower voltage switches from being used for higher voltages.

It's 1/4" extra. You can take a Decora switch and put one screw through the normal hole, and one through the hole for the cover plate (yes I've see that once)