Circuit breaker help please

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  #1  
Old 11-20-14, 02:43 PM
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Circuit breaker help please

Hi guys so I am about to be running a continuous load of around 700 watts. The recepticle is on what I thought was a 15A breaker. But 700w is about 6A, at 80% usage on a 15A is roughly 12A correct? Leaving me 6A to spare. Nothing else is really run off this line except for the occasion band saw and. Maybe 100w of flouro lighting over my work bench. My issue is that isn't all lighting (because continuous supposed to be on 12/2 awd and if this is a 15A than it's 14/2 awd bc it's not a line to lighting. Wouldn't this pose a fire issue running that many watts continuos on 14/2 wire even though my amperage is in a safe range?

Second issue. I looked at the breaker closely and it's what I belibe is called a duplex (it has 2 switches) I assumed they were 15A each bc small but when looking closely each switch has 20 on it. So... Do each of these switches support 20A or is that split giving each 10A. Also I have to still search but right now I have no clue what one of the switches control. Could this be that one isn't connected to anything so the other gets the full 20A? Because then the wiring should all be 12/2 right? All the breakers are pretty much like this and all the wires coming out appear to be thicker than 14/2 but the house was built in 1981 and the wires are all white (I distinguish wire size based on yellow being 12/2 and white 14/2 based on my home improvements.

This would be ideal bc then I'm way under the 80% of the breaker amperage and I have 12/2 wire feeding my recepticle.

Lastly if it's not safe and i do need to put in a dedicated 20A line how do I know if I have enough room in my breaker panel it's pretty full. But I have 4 open spaces. I have another panel for the second floor but I'd rather not use it.

Ok I think that's it thanks as always in advance!!

S
 
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  #2  
Old 11-20-14, 03:44 PM
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What size wiring do you have on the 20 amp breaker. Just because they are together doesn't mean they control the same circuit. Have you identified the breaker that protects your workshop? If it is 20 amps, you should have 12-2 wiring to the receptacle. Generally lighting is wired from a different breaker, but not always. Earlier cabling was all white, so don't go by the color of the sheathing. Look on the sheathing to see what size you have.
 
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Old 11-20-14, 04:05 PM
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The issue you have seems to be the possibility of #14 on a 20 amp circuit.

If you have a tandem breaker it is actually two breakers in the space of one. Each breaker will support the handle rating. It does not split between the two.

The 80% rule only applies to loads considered continuous or on for 3 hrs or more. Residential lighting is not considered continuous.

Other than that you have some misconceptions.
 
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Old 11-20-14, 04:05 PM
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Thanks for the reply. Well there are 2 switches on the one breaker both say 20 on it and one deff controls my workshop recepticles and I ran another recepticle off that. The other switch on the breaker as far as I can tell now, when I turn off nothing turns off so I'm thinking maybe it goes to outside lights, gonna check tomorrow. But if this kind of breaker with the 2 switches on it each say 20A is my workshop on a 20A breaker? I didn't open the panel yet to follow the line on that breaker but none of the wires have anything written on them and some do look thicker than others but I can't really tell
 
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Old 11-20-14, 04:34 PM
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Then you have a 20 amp service to the workshop. You will need to determine the size of wire to make sure it is sufficient (12) to handle the amperage. If it is 14, you will need to introduce a 15 amp breaker, or (better) run 12-2 cable from the breaker to the shop so you will have enough. If you have a wire stripper, place the stripper on the wire in the 12 hole. If it strips it, most likely it is 12 gauge wire. Reading the writing on the side of the cable is a better indicator.
 
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Old 11-20-14, 06:48 PM
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Thanks again guys. This isn't a random breaker the work shop is part washroom/finishe basement and done from when the house was built so I'm assuming if code was 12/2 on a 20A that it is. Yes my worries were originally that I would be putting a continuous load of 700ishwatts for way longer than 3 hrs on a 15A breaker bc it would be supporting 14/2 wiring which isn't good for such a heavy continuous load, until I looked today and the breaker is a tandom 20A (thank you for clearing up that I do I fact have 20A on each of these.

But I did run another recepticle off this line using 14/2 wire bc I was under the misconception it was on a 15A line and that all the recepticles in the house were on 15A after looking it makes sence the workshop area would have a 20 and the basement it self has a 15A... I wish it was all 20A so I can go up to 220 one day :-)

So thanks very much guys you cleared up so much. Tomorrow when I change the 14/2 wire I used for my new recepticle to 12/2 ill double check with my wire stripper that it is in fact 12 but since it the house was built in '81 if that was code than I'm pretty confident it's 12/2 on the 20A and I can also tell some lines coming out of the box are bigger than the others. It would be major cutting walls to run a new 12/2 from this box to the room, as it's all very finished work and all wires were from when the house was built
 
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Old 11-20-14, 07:31 PM
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You do not need #12 for a 240 volt circuit. The wiring size is based on the expected amps, not the voltage.
 
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Old 11-20-14, 08:12 PM
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Ohhh I just assumed something I never looked into. Love this forum. I would just have to have my electic company come and run it to the house right?
 
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Old 11-20-14, 08:15 PM
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Most houses already have a 120/240 volt service. Your house would need to have a very old service to only have 120 volts available.
 
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Old 11-20-14, 08:38 PM
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If you have three wires to your meter you have 240v.
 
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Old 11-21-14, 04:38 AM
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Can you help educate me? I thought it was either 120 or 240? 3 wires where at the meter? When I test anything in the house it always reads 120V I assumed if it were 240 it would read 240?
 
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Old 11-21-14, 04:56 AM
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Look at your overhead feed to the meter. There should be three coated wires plus a ground tension wire. Do you have an electric stove? Electric water heater? Central heat? If so you have 240 volt service. Do you have any double breakers/fuses?

You are reading hot to neutral to get your 120 volts. On a large appliance you read across both hots to check for 240 volts. A 240 volt circuit needs no neutral. Complicated to explain.
 
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Old 11-21-14, 05:02 AM
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All modern houses (circa 1950 and newer) have 240 volts. The 240 volts is two wires. A third wire, neutral, is used to derive 120 volts using the neutral and one of the 240 volt legs. If your house has 240 you will see two insulated wires (the 240) wrapped around an uninsulated steel cable (the neutral.

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Old 11-21-14, 08:47 AM
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the wires are all white (I distinguish wire size based on yellow being 12/2 and white 14/2 based on my home improvements.
Those are white cables, not white wires. When your house was built there was no standardization on color of the cable sheath. The sheath could be white, blue, tan, black or any other color. Today the 12 AWG cables are yellow and the 14 AWG cables are white.
 
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Old 11-21-14, 09:37 AM
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Thanks!! I'm a diyer that likes to really understand things. I'm going to look at the wires coming into the meter when I get home. The only electic appliance is 2 central air units both on double breakers
 
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Old 11-21-14, 09:40 AM
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The only electic appliance is 2 central air units both on double breakers
The 2-pole breakers are 240 volts.
 
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Old 11-21-14, 12:49 PM
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Awesome guess I have 240 coming to the house great to know thanks!!
 
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