# 240v heat on 120 circuit.



## philcav7 (Jan 15, 2009)

I went to fix a faulty elect baseboard heat for a client. Expecting to find a bad t-stat, I opened it up and discovered the 240 unit is being supplied by a 120v line. 

It was 7:00pm and didn't have time to figure out the circuits, loads, etc so I buttoned it up and told them I would return this weekend. I have no idea if it's a dedicated circuit or tied into other heaters, receptacles, etc. 

My question is: is it reasonable to run this heater on 120V? I've never seen it done and I realize that it will yeild reduced performance, but does actually work?

I'm really hoping the heat is a dedicated line so I can simply put it on a double pole breaker, but I have a strong suspicion that it's tied into the receps in that room.


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## Golden view (Feb 16, 2012)

Ohms law. V=IR. One fourth the wattage at 120v


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## aaron_a (Dec 18, 2013)

I'm no electrician, but I'm pretty sure they're run on 12 ga on a two pole breaker most of the time.


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## rselectric1 (Sep 20, 2009)

aaron_a said:


> I'm no electrician, but I'm pretty sure they're run on 12 ga on a two pole breaker most of the time.


That's the norm.


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## aaron_a (Dec 18, 2013)

rselectric1 said:


> That's the norm.



No neutral so both wires are hot, correct?


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## Tinstaafl (Jan 6, 2008)

While 240V heaters are more common and a tad more efficient, there are plenty of 120v heaters out there. Read the tag before you jump to any conclusions. :thumbsup:


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## Golden view (Feb 16, 2012)

aaron_a said:


> No neutral so both wires are hot, correct?


Yes so the white should be tagged with any color other than white or green.


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## philcav7 (Jan 15, 2009)

Golden view said:


> Ohms law. V=IR. One fourth the wattage at 120v


Right. But would it be capable of actually heating a room? It's a 4' heater, I believe they are 1000W at rated voltage. It seems that a toaster would put out more heat. 



aaron_a said:


> I'm no electrician, but I'm pretty sure they're run on 12 ga on a two pole breaker most of the time.


Yup. It will be simple to convert as long as heat is on a dedicated circuit. There is hydronic heat downstairs. This electric heat was added during a poorly executed addition. That's why I'm expecting the worst case scenario of it being tied into a branch circuit. From my logic, if it were put on a dedicated heating circuit, it would already be correctly wired at 240v.


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## Tinstaafl (Jan 6, 2008)

Cadet 4F1000-1A 1000-Watt 120V 4-Foot Electric Baseboard Heater, Almond


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## philcav7 (Jan 15, 2009)

Tinstaafl said:


> While 240V heaters are more common and a tad more efficient, there are plenty of 120v heaters out there. Read the tag before you jump to any conclusions. :thumbsup:


No doubt. At this point, I'm just not sure what the load on the circuit is. Running a 120v unit will draw around 8/9 amps for that single unit. That may work fine or I may find that the heaters/lighting/outlets in other rooms are tied together and will not support the increased current draw. 

Moreso than anything, I'm just curious if I have to keep it as is, will it actually heat the room. This room had previously been used as storage and the heat wasn't used. It has become occupied by current tenants. 

Thanks again, all.


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## Anti-wingnut (Mar 12, 2009)

Tinstaafl said:


> While 240V heaters are more common *and a tad more efficient,* there are plenty of 120v heaters out there.


How so?


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## Tinstaafl (Jan 6, 2008)

Anti-wingnut said:


> How so?


I'm surprised you need to ask. With a higher voltage, there is a lower percentage of voltage drop over a given length of wire.

That's why the POCOs jack it up to thousands of volts for the long runs.


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## Golden view (Feb 16, 2012)

Anti-wingnut said:


> How so?


A little less heat in the wires in the walls or crawlspace or attic, but still pretty close to 100% like all electric heat.


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## Golden view (Feb 16, 2012)

philcav7 said:


> No doubt. At this point, I'm just not sure what the load on the circuit is. Running a 120v unit will draw around 8/9 amps for that single unit. That may work fine or I may find that the heaters/lighting/outlets in other rooms are tied together and will not support the increased current draw.
> 
> Moreso than anything, I'm just curious if I have to keep it as is, will it actually heat the room. This room had previously been used as storage and the heat wasn't used. It has become occupied by current tenants.
> 
> Thanks again, all.


1/4 the power = 1/4 the heat. so unless it was 4x oversized, it won't heat the room.


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## tjbnwi (Feb 24, 2009)

Golden view said:


> Yes so the white should be tagged with any color other than white or green.


Not allowed under NEC 200.6. 

Tom


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## Anti-wingnut (Mar 12, 2009)

Tinstaafl said:


> I'm surprised you need to ask. With a higher voltage, there is a lower percentage of voltage drop over a given length of wire.
> 
> That's why the POCOs jack it up to thousands of volts for the long runs.


I was being facetious, I don't buy your math at all. Same efficiency except with extreme significant digits


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## Golden view (Feb 16, 2012)

tjbnwi said:


> Not allowed under NEC 200.6.
> 
> Tom


Explain.


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## tjbnwi (Feb 24, 2009)

Golden view said:


> Explain.


NEC 200.6 (A) requires the color (white or gray) to be continuous along the entire length of the conductor for any 6 AWG or smaller connector. The only exceptions in the code are for the white conductors in cords or use as a leg for a 3 way switch.

NEC 200.6 (B) allows the color (white or gray) to be continuous or marking of a cable 4 AWG or larger at the terminal at time of installation (200.6 (B)(4). 

If the AHJ has amended the NEC, that would be the procedure to follow.

https://www.inkling.com/read/nation...ion-association/chapter-2/article-200-use-and

Tom


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## Golden view (Feb 16, 2012)

tjbnwi said:


> NEC 200.6 (A) requires the color (white or gray) to be continuous along the entire length of the conductor for any 6 AWG or smaller connector. The only exceptions in the code are for the white conductors in cords or use as a leg for a 3 way switch.
> 
> NEC 200.6 (B) allows the color (white or gray) to be continuous or marking of a cable 4 AWG or larger at the terminal at time of installation (200.6 (B)(4).
> 
> ...


Yes... So when re-purposing the white for an ungrounded conductor, you tag it on all ends (not white, green, or gray, I missed gray). The verbiage about switches is another situation, not an exception. 

Granted, I'm not an electrician, but I communicate closely with my sparkys and inspectors.


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## tjbnwi (Feb 24, 2009)

Golden view said:


> Yes... So when re-purposing the white for an ungrounded conductor, you tag it on all ends (not white, green, or gray, I missed gray). The verbiage about switches is another situation, not an exception.
> 
> Granted, I'm not an electrician, but I communicate closely with my sparkys and inspectors.


Not allowed by code to tag any white or gray conductor smaller than 6 AWG. 

The switch leg Article (200.7) was written to exempt the white lead from the 200.6 rule. To me that makes that one situation an exception to this rule. It is the only situation where tagging the conductor is allowed in a raceway.

Again, if the AHJ has adopted the NEC and has adopted an exception to 200.6 (A), that becomes the prevailing code.

The 2011 NEC clears some of this up by changing the wording. 

http://electriciantesting.blogspot.com/2010/12/significant-2011-nec-code-changes-part.html

Tom


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