Wire capacity in 1/2 emt?


Old 05-23-05, 01:58 AM
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Wire capacity in 1/2 emt?


I'm laying out an electrical plan for my basement using 1/2" EMT. I know code says 40% cap. but how many wires is "good" to run in each piece of EMT. I'll be using just 12 and 14 awg insulated wire.

Also is it ok by code to run EMT to a room then run romex from a junction box to the outlets? I want to run EMT in case of future runs.

And what's the deal with running seperate curcuits for lighting and outlets.

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Old 05-23-05, 05:43 AM
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I can't help you much with the fill issue.

Yes, you can mix and match wiring types, as long as each wiring type is allowed in your area and as long as all is properly done (no hidden junction boxes, etc.).

You can mix lighting and receptacles on the same circuit if you wish, as long as you are not talking about kitchens, dining rooms, laundry rooms and bathrooms (certain situations).

Many people don't like to mix the two, but you can do so. One disadvantage is that if you trip the breaker because you run the vacuum and the iron at the same time you may find yourself in the dark.
Old 05-23-05, 07:32 AM
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I have not compared the chart below with the NEC, but it is a start.
If you want to mix sizes, then check out this reference for calculating yourself.
Old 05-23-05, 07:46 AM
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As the chart Ron presented, as well as the NEC, say, you can put 12 #14 or 9 #12 in 1/2" EMT.
Old 05-23-05, 06:03 PM
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Wow I didn't expect that many wires in 1/2 emt. I was planning 4 to 6 - 14ga and 2 - 12 ga. in each conduit. Now I have some more thinking to do. My house is wiring is FU. 1/2 the outlets in the kitchen are on one circuit and the other half on another. The whole house is like this. I got zapped a couple of times thinking all the outlets are dead when I shutoff the circuit. Now I test every outlet before servicing. That's why in the basement I installed a subpanel and are going to seperate each room into it's own circuit (or two)

Old 05-23-05, 07:22 PM
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Remember to consider the adjustment factor when there are more than 3 current carrying conductors are in conduit.If you have 6 current carrying conductors in a pipe run the allowable ampacity of each must derated by a factor 80%. For example AWG # 14 {type THHN} has an ampacity of 25 amps therefore it would be derated to 18 amps, AWG # 12 has a rating of 30 amps but is derated to 27.6 amps {per NEC 310.15{2} & {B}{2}{a}. Obviously the overcurrent proetection of these conductors shall not exceed 15 amps & 20 amps respectively {per NEC 240.4{D}}
Old 05-24-05, 09:25 AM
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Originally Posted by mightybhwk
1/2 the outlets in the kitchen are on one circuit and the other half on another.
The kitchen circuits are probably supposed to be like that! The general purpose receptacles in the kitchen must be on two circuits. I think what you're describing is split-wired receptacles which is a common method for providing two circuits to the kitchen countertops.

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