Need help with wiring questions

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That's a common misunderstanding.

Perhaps *you* won't ever turn on all the heaters at once, but what about the next homeowner? Resistance heating is definitely subject to the 80% rule, which means that the circuit is limited to 15A * 240V * 80% = 2880 watts. Four 750W heaters is 3000 watts. Not much over the limit, but still over. With all four in use, the breaker won't trip, but it is possible to overheat the circuit conductors.

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On Oct 25, 11:27 am, snipped-for-privacy@milmac.com (Doug Miller) wrote:

I hear your concerns. While I plan to own this place for many years, I am a big proponent of doing things right and not handing my problems off to someone else. I certainly could not handle it if any harm came to someone downstream from my actions.
I will add a new circuit and string a new 14 gauge wire for the new heater.
Again my thanks to the group knowledge base.
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On Oct 25, 5:09 am, snipped-for-privacy@milmac.com (Doug Miller) wrote:

If I can add an additional question - just for my personal knowledge...
At a junction box, why is it bad to step down the gauge of a wire to match the draw of the load on that wire? In my case, if I had 12 gauge wire to a junction box, why would 14 gauge from the box to the individual heaters be a violation? If each is only capable of drawing a few amps, and the "pipe" to the box is big enough?
Tnx
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Because the Code says so. There are only a few exceptions, and AFAIK this isn't one of them.
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Doug Miller wrote:

I asked an actual electrician about this once, and he said it was because the NEXT silly SOB might add yet something else to that leg of the circuit. (Hey! I can grab power from that box right there! etc...)
-- aem sends...
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gwandsh wrote:

There is nothing wrong with that, but (with a few exceptions*) the breaker has to protect the smallest sized wire. So with a long run of 12 gauge wire (to reduce voltage drop) that then taps off with a 14 gauge wire, you need a 15A breaker.
*there are some exceptions, like the "10 foot tap rule" which might be used for a kitchen with a split cooktop and oven on the same 40A circuit.
Bob
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"gwandsh" wrote

I can't answer specifically being electrically challanged (grin), but i do know when we had our sunroom install, we opted to have 2 of the outlets direct to my under-utilized electrical service box. The house was upgraded from 100 amp to 200 amp service about 15 years ago. The electricians smile when they see the box as apparently we have oodles of excess there. Enough to run plenty more outlets direct without 'sistering'.
Hence I have 2 outlets in the sunroom each on their own line, and a reserved line set aside if we want to run a 240V back there for a powerful heater. I don't know enough to say more other than we asked both be able to run anything at the same time with a standard 3 prong plug such as an accessory AC unit or accessory heater. Obviously we wouldnt be heating and cooling at the same time, but you get the drift. I've used my 1500watt heater with no problems. When it gets really cold, I also plug in (other outlet) the monster radient heater to take the chill off fast.
This summer, we had an extra line run as well for the garage heater. Heats 400sqft, set at lowest to keep pipes from freezing. It's all on it's own circuit too (GFCI not required but we did that for added safety as its other side of the kitchen sink with water lines over it).
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A 15 amp load is OK on a 14 gage wire. If you were running the same heaters on 120v you would be in trouble.
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On Wed, 28 Oct 2009 04:48:58 -0800, "Roger Shoaf"

If he ran "the same heaters" on 120v he wouldn't be in trouble but he might be cold. A 1000w 240v heater is a 250w heater at 120v.
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On Wed, 28 Oct 2009 04:48:58 -0800, "Roger Shoaf"
[snip]

Those heaters which draw 13.5A at 240V (3240W) will draw 6.75A at 120V (810W). The trouble isn't electrical.
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Thought I would finish the story here. We decided to keep the 1000 watt/ 240V heater unit since there would be no load issues with the new circuit.
I ran a new circuit with 14/2 Romex to the heater location, leaving six feet of wire hanging beside the panel. I bought and wired the (internal) thermostat for the heater according to the supplied diagram, and bought the compatible 2 pole 15 amp circuit breaker.
My electrician friend visited - he verified my thermostat wiring, checked the wire routing, wired and installed the new circuit breaker all in about 10 minutes. Works like a champ.
The whole thing took a while to figure out, but little time to implement. We now have warm floors when needed in the kitchen. Tnx to everybody who helped out.
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