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CooperChloe 02-03-2009 11:57 PM

240 v Space heater plug?
I added my 30 amp breaker and outlet. Now, The plug I have on the space heater now (240 volts, 20 amp) needs to be replaced. Can I just add a 30 amp plug? What do I do about the chord? Do I need a new one or can I just add the new 30 amp plug to replace the old 20 amp plug? I've heard about 5 different answers from electricians. I'm wondering if I should've just kept the plug as it was and went with a 20 amp outlet. Problem is the heater draws 16.7 amps, which is why I went with the 30 amp breaker to avoid the surge issue and being above the magic 80% of the load. By the way, the heater is 4000 w. Just want to make sure I'm doing this right. I really am frustrated that so many electricians have different answers. Thanks!

kbsparky 02-04-2009 06:43 AM

If the heater came equipped with a 20 Amp plug, then you need to install a 20 amp receptacle. :yes:

I'd guess you need a NEMA 6-20R. :wink:

Change the outlet to match the heater, and install a 20 Amp breaker.

Otherwise, you most likely will void any warranty on the unit, and violate any UL listing as well. :whistling2:

jbfan 02-04-2009 07:11 AM


Originally Posted by CooperChloe (Post 224793)
I've heard about 5 different answers from electricians.

Well, I agree with kb. Now you have heard from two that tell you the same thing!:thumbup:

HouseHelper 02-04-2009 08:10 AM


Originally Posted by jbfan (Post 224870)
Well, I agree with kb. Now you have heard from two that tell you the same thing!:thumbup:

Make that three...

rgsgww 02-04-2009 08:16 AM

Not an electrician, but I agree, you should change the receptacle and breaker.

Stubbie 02-04-2009 12:18 PM

I also agree. Where your getting your misinformation is the 80% rule. If your heater plugs into a individual single receptacle dedicated to that heater then you can run that branch circuit at 100% of its rating as long as the load is not continuous. A cord and plug heater is not a continuous load. The 80% rule has to do with cord and plug equipment, appliances, etc.. that are used on general purpose branch circuits that serve more than one outlet. A duplex receptacle is 2 outlets. In this case your not supposed to plug anything into one of those outlets that exceeds 80% of a branch circuits rating. For a 20 amp branch circuit that would be 16 amps. But there is no way to control what people plug into multiple receptacles on a branch circuit this is just the code requirement.

micromind 02-04-2009 08:23 PM

Even though 4000 watts at 240 volts is 16.67 amps and is, at times, a technical code violation to supply with a 20 amp circuit, I can't even think of how many times I've done exactly that. Most of my work is inspected, and I've never been busted for it.

In reality, a 20 amp circuit will run a 4000 watt load for a long, long time. Completely safely.


Stubbie 02-04-2009 08:25 PM

I concur (but I don't agree....:)) if I do.. then the internet police will put us both in jail.

Scuba_Dave 02-04-2009 09:05 PM

So, no-one saying that they should absolutely NOT put this on 30a ?


kbsparky 02-04-2009 09:13 PM

You should not plug a NEMA 6-20P into a 30 Amp circuit. :furious:

Scuba_Dave 02-04-2009 09:16 PM

Woops - missed that
Everyone basically did say not to use the 30a breaker :surrender:

rgsgww 02-04-2009 10:40 PM

Any 20 amp receptacle or plug on a 30 amp circuit is a no-no.

micromind 02-04-2009 11:57 PM

It's OK to feed a 20 amp receptacle with #10 wire, it's not OK to feed it with a 30 amp breaker.


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