double pole switch for mulitiple ckts

[ccha9219]

I was ask this question today
"is it legal to put a double pole switch in a single gang device ring to control two ckts for lighting?" I don't know...If so what about ocpd. two ckts on one switch could pose a hazzard to someone working on it. A helper remarked "use a two pole breaker with a common trip"

I have looked and can't find a ruling on the switch question...the two ploe breaker is not an option.
I'm thinking 10x10 j box, contactor ect...ect..
still wondering about the switch though???
craig

 

[electricman2]

Re: double pole switch for mulitiple ckts

From the UL white book category WJQR snap switches:

Multi-pole, general use snap switches have not been investigated for more than single circuit operation unless marked "2-circuit" or "3-circuit."

Sounds like it would violate the listing unless marked for that use.

 

[websparky]

Re: double pole switch for mulitiple ckts

As long as the voltage does not exceed 300V between phases and it is a two circuit switch (not a 4-way), you should be fine.

 

[ccha9219]

Re: double pole switch for mulitiple ckts

no ,it is a two pole 277/480 rated switch, but the ocpd problem still bothers me.Don't want anyone hurt how can you affectivly protect 2 ckts @ one switch?
craig

 

[websparky]

Re: double pole switch for mulitiple ckts

Craig,

I guess I don't understand your question?

Light switches don't protect anything. They meerly energize the fixtures...right?

If you are talking about a typical wall switch for 277V lighting, both circuits would have to be the same phase so the potential between them is zero volts and to ground, 277V.

 

[iwire]

Re: double pole switch for mulitiple ckts

Originally posted by websparky:
As long as the voltage does not exceed 300V between phases and it is a two circuit switch (not a 4-way), you should be fine.

Dave I am not sure that would apply, that would be for adjacent devices.

If it does apply that means you could not use a 20 amp two pole 480+ volt switch to control a single phase 480 volt load, say HID lighting.

 

[pierre]

Re: double pole switch for mulitiple ckts

Actually the two pole switch will be able to carry two different circuits.
Reading 404.8(B) I see that the voltage between the two switches would be greater than the permitted 300v. But how do we determine what 'adjacent' means? Does it mean two physically different switches? Or does it mean two switches that are 'adjacent'? Without a definition of adjacent it is hard to tell.
Dictionary definition: near or next to..
Are these switches near or next to each other...or are they attached to each other?

Pierre

 

[iwire]

Re: double pole switch for mulitiple ckts

404.8(B) Voltage Between Adjacent Devices. A snap switch shall not be grouped or ganged in enclosures with other snap switches, receptacles, or similar devices, unless they are arranged so that the voltage between adjacent devices does not exceed 300 volts, or unless they are installed in enclosures equipped with permanently installed barriers between adjacent devices.

One double pole switch = one device, yes?

 

[websparky]

Re: double pole switch for mulitiple ckts

Hi Bob,

I think the intent for safety is described here;

404.5 Time Switches, Flashers, and Similar Devices.
Time switches, flashers, and similar devices shall be of the enclosed type or shall be mounted in cabinets or boxes or equipment enclosures. Energized parts shall be barriered to prevent operator exposure when making manual adjustments or switching.
Exception: Devices mounted so they are accessible only to qualified persons shall be permitted without barriers, provided they are located within an enclosure such that any energized parts within 152 mm (6.0 in.) of the manual adjustment or switch are covered by suitable barriers.

Yes the snap switch is ONE device just as a lighting contactor is ONE device. However you will note the requirements for contactors kind of set the standard for most of our control devices.

 

[ryan_618]

Re: double pole switch for mulitiple ckts

I agree Bob...it is one device.

I must confess though, I was just about to bring up the 300-V provision when I saw that Dave had beat me to it.

 

[iwire]

Re: double pole switch for mulitiple ckts

Dave I do not see how contactor requirements or 404.5 come into this at all.

If I install a correctly rated snap switch in a single gang box or a box with a barrier there is no reason I can not control a 480 volt load.

Yeah I would have more than 300 volts from one side of the device to the other.

 

[roger]

Re: double pole switch for mulitiple ckts

I agree with Bob.

A handle tie on the breakers takes care of the safety concerns.

If nothing else, just share the neutral and you have "one" circuit.

Roger

 

[websparky]

Re: double pole switch for mulitiple ckts

I'm still not convinced!

The Handbook commentary uses different terminology.

Barriers are required between switches that are ganged in a box and used to control 277-volt lighting on 480Y/277-V systems where two or more phase conductors enter the box. Permanent barriers would be required between devices fed from two different phases of this system because the voltage between the phase conductors would be 480 volts, nominal, and would exceed the 300-volt limit. Barriers are required even if one device space is left empty because the two remaining devices fed from different phase conductors would still be adjacent to each other. This requirement now applies to switches ganged together with any wiring device where the voltage between adjacent conductors exceeds 300 volts.

 

[roger]

Re: double pole switch for mulitiple ckts

Dave, that would only apply to more than one yoke, in otherwords multiple devices.

Let me throw a "for instance" in the fire.

We have a 480 volt unit heater in a stairwell, instead of using a safety switch or enclosed breaker we decide to use a flush mount double pole toggle switch for the disconnect.

Would you see a violation with this installation?

Roger

 

[pierre]

Re: double pole switch for mulitiple ckts

Roger
I agree with your example of a double pole switch. What do you think about two single pole switches that are on the same yoke (strap), where the tab is broken so two circuits can be switched?

Pierre

 

[iwire]

Re: double pole switch for mulitiple ckts

Dave I do not see how the wording in the handbook is different.

From NEC handbook:
Permanent barriers would be required between devices....

Still saying between devices, not between terminals.

Originally posted by roger:
We have a 480 volt unit heater in a stairwell, instead of using a safety switch or enclosed breaker we decide to use a flush mount double pole toggle switch for the disconnect.

Roger thanks, that is the type of installation I was thinking about.

I also do not think that two single pole switches on one yoke are available rated for 480 volts.

 

[websparky]

Re: double pole switch for mulitiple ckts

It is interesting that the code has the requirement of a 300V limit between two devices and yet we are able to purchase and install listed toggle switches rated for 277V in a double pole configuration which will put 480V in the same single gang box.
I fail to see the logic in the code's requirement because I fail to see the logic of how this is safer than if we used 2 single pole switches rated at 277V installed in the same double gang box.

Logic please??

 

[iwire]

Re: double pole switch for mulitiple ckts

Dave I am going to take a guess here.

I do not believe there is anything inherently dangerous about 480 volts in a device box.

When taking about a double pole switch it has been tested for this use and the spacing between the terminals even if the switch is bumped around or moved is maintained, if one side of the same device moves the other side moves too.

Now my guess is the danger comes in when I put two specification grade 20 amp 277 volt switches side by side on opposite phases.

Lets say these are 3 or 4 way switches, that means live terminals on both sides of the devices and with the large size of these switches at best there might be 1/2" of space between the the terminals of the two devices when spaced for the plate to fit, take the plate off and bump one of these devices and the terminals may actually touch each other resulting in a 480 volt arc which will surly result in a 'hot shower' of metal.

This is all just guessing on my part and no one should bet the farm on it.

Bob