# Disconnect as raceway.



## TimChaput69 (Nov 14, 2011)

Don't have the code book with me and trying to remember the code article that doesn't allow 120v to be run through a 480v disconnect for rooftop unit. Any one have the code ref?


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## wingz (Mar 21, 2009)

Probably allowed. See 312.8 and 300.3(C)(1). 2011 NEC.


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## TimChaput69 (Nov 14, 2011)

Thanks for the point in the right direction, always thought it was not legal to run 480v and 120v in same raceway then through the disconnect and into a receptacle.


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## wingz (Mar 21, 2009)

TimChaput69 said:


> Thanks for the point in the right direction, always thought it was not legal to run 480v and 120v in same raceway then through the disconnect and into a receptacle.


Common install for HVAC.


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## TimChaput69 (Nov 14, 2011)

Yeah, I've seen it that way about a thousand times but for some reason just thought it was wrong....I guess as long as you don't exceed 600v or wiring space its all good! Thanks again .


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## TimChaput69 (Nov 14, 2011)

Now that I've found the code ref, thats made me think about it!!! Actually it could be a code violation depending on the conditions.

Example: 208V, 3 phase, circuit in a 250V disconnect, by code you can't bring another 120v circuit through because then you violate the UL listing of disconnect ,then you'll be over 250V, correct? So its not really an across the board correct assumption that using the rooftop unit disco as a raceway is correct...correct? Unless would it be code compliant if the 110V circuit is brought out of the same panel as the rooftop unit is fed from?


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## Bbsound (Dec 16, 2011)

TimChaput69 said:


> Now that I've found the code ref, thats made me think about it!!! Actually it could be a code violation depending on the conditions.
> 
> Example: 208V, 3 phase, circuit in a 250V disconnect, by code you can't bring another 120v circuit through because then you violate the UL listing of disconnect ,then you'll be over 250V, correct? So its not really an across the board correct assumption that using the rooftop unit disco as a raceway is correct...correct? Unless would it be code compliant if the 110V circuit is brought out of the same panel as the rooftop unit is fed from?


Where in your proposed situation could you connect a meter and measure over 250 volts?


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## TimChaput69 (Nov 14, 2011)

Bbsound said:


> Where in your proposed situation could you connect a meter and measure over 250 volts?


Obviously you can't but does that matter? If you have a four square box with no splices your still limited to 600v correct? Meaning if you pass 480v from two separate systems in a box (which you can't meter unless you cut wires to measure), you still violate 600v. So by that meaning if the enclosure is only rated 250v whether or not it can be measured easily or not shouldn't matter I would think.


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## TimChaput69 (Nov 14, 2011)

Donno! Maybe (probably) I'm all backassward about it and not thinking about it the right way!!! Wouldn't be the first time.


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## Bbsound (Dec 16, 2011)

If a device is rated 250 volts, then as long as you have no potential above 250 volts then you are fine. You can have as many 240 volt conductors (as allowed by other sections of the code) as you want, you do not add the voltages together.


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## TimChaput69 (Nov 14, 2011)

Bbsound said:


> If a device is rated 250 volts, then as long as you have no potential above 250 volts then you are fine. You can have as many 240 volt conductors (as allowed by other sections of the code) as you want, you do not add the voltages together.


Then why is it that in a switch box with a 277v switch and a 120v switch is it required to have a divider?...and I also remember something about 300v. (Really not trying to be an a**) guess I never fully understood this before now! Somehow it got around me until today I guess:-(


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## niteshift (Nov 21, 2007)

What I've always seen and done is the 600v requierment for conductors in same enclosure/raceway. 480v to 120v don't forget the dc, are always in the same enclosure for machine control. Wireways are filled with differant voltage conductors for example. Ladder racks also.


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## niteshift (Nov 21, 2007)

TimChaput69 said:


> Then why is it that in a switch box with a 277v switch and a 120v switch is it required to have a divider?...and I also remember something about 300v. (Really not trying to be an a**) guess I never fully understood this before now! Somehow it got around me until today I guess:-(


termination points with moving parts(disconnects come to mind) dividers are also between phases not just low to high voltages.


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## TimChaput69 (Nov 14, 2011)

niteshift said:


> What I've always seen and done is the 600v requierment for conductors in same enclosure/raceway. 480v to 120v don't forget the dc, are always in the same enclosure for machine control. Wireways are filled with differant voltage conductors for example. Ladder racks also.


Yeah, I get what you guys are saying.....I'm around the stuff all day but today has been rather slow waiting on a part and my head got hold of this and just spun it around all day!!! Sometimes I swear I could convince myself up is down and down is up!!! Thanks again for all your responses too by the way.


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## BBQ (Nov 16, 2010)

I would think nothing of running 480 volt circuits through a 250 volt disconnect. In my opinion the 250 volt rating has to do with the switching contacts not the enclosure.

By that logic the supply to the disconnect could not exceed the current limit of the disconnect. 

What is the voltage rating of EMT or a 4" square box?


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## niteshift (Nov 21, 2007)

BBQ said:


> I would think nothing of running 480 volt circuits through a 250 volt disconnect. In my opinion the 250 volt rating has to do with the switching contacts not the enclosure.
> 
> By that logic the supply to the disconnect could not exceed the current limit of the disconnect.
> 
> What is the voltage rating of EMT or a 4" square box?


I agree with that BBQ. But more unimportant is the melting point:laughing:, with a little encouragement someone here would volunteer to do the test.
I pass, any takers?


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## TimChaput69 (Nov 14, 2011)

Thats what got me thinking about all this crap in the first place!! I would think the voltage rating of emt or a four square to be 600V cause thats the voltage we are limited to. Besides a control cabinet I've always been taught to limit the combination of voltages, especially of separate systems....anyway. Long story short I saw something this morning and got to "think" about it all day!! Now everyones gonna have a field day tonight with it....well have at it!


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## Cl906um (Jul 21, 2012)

312.8 page 165.


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