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post #1 of 14 Old 03-03-2013, 07:35 PM - Thread Starter
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Simple question, can I split a electrical line into 2 lines? A 20 amp lines I want to tap into goes into a wall i cant access, therfore, before it goes into the wall I want to cut it and make two lines. Its in the attic so I can nail in a box the a 2x4 and house the split in there.

Is this safe, and an acceptable activity a far as electrical codes go?

Sorry for the misspelled title, damn computer sucks!

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post #2 of 14 Old 03-04-2013, 05:04 AM
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as long as the junction box remains accessible you can split the line inside the box. Wiring on a circuit most all be the same gauge and in this case with 20 amps it should all be 12 gauge.
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post #3 of 14 Old 03-04-2013, 06:36 AM
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And make sure you have enough slack in the line you are cutting to tie everything back together. Once you cut that line and pull it into the new box, you need to have enough slack to strip the ends to tie together with the new line. You'll need a good 6 to 8 inches. (Yeah I know...that's what she said!)

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post #4 of 14 Old 03-04-2013, 07:36 PM - Thread Starter
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Thanks guys, just to make sure were all on the same page....

The main panel box is in the garage, a 20 amp line runs up into he attic and then into a wall too difficult to get into to. Therefore i want to cut the line in the attic and create two seperate lines out of it. I can house all this in a new/old work box (nailed to a 2x4).

From the two new lines, one will be tied back together with the cut line going into the difficult wall, the other new one will be ran into my bonus room.

Sorry for the over kill but i just want to be very sure i'm not doing anything wrong!

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post #5 of 14 Old 03-04-2013, 07:59 PM
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I would also map out all the devices on that circuit. Code allows for a maximum of 12.
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post #6 of 14 Old 03-04-2013, 08:04 PM
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If I understand what you've posted correctly, that sounds right. IIRC, you need to use a Jbox with a cover, and you need to make sure you use the correct fittings going into the box to secure the wire. Use the correct wire nuts as well. The only gotcha's that I can think of are with regard to certain rooms/loads require dedicated circuits and/or AFCI or GFCIs. That may or may not apply to your specific case.

Edit: +1 to what TMcG said.

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post #7 of 14 Old 03-05-2013, 03:52 AM
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There's no limit to the number of receptacles on a circuit in a US dwelling.

However, you should figure out what you're tapping into; no sense in tapping into a circuit that's already heavily loaded.

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post #8 of 14 Old 03-05-2013, 04:55 AM
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Quote:
Originally Posted by Mr.Tim View Post

There's no limit to the number of receptacles on a circuit in a US dwelling.

Technically speaking, you are correct as the code is a bit murky in this area. A device (receptacle, switch etc) by definition does not consume any energy so there is no load added to the circuit by installing any number of receptacles. The problem occurs when too many loads are plugged into those receptacles.

The rule of thumb goes like this:

Because a normal circuit breaker can only be loaded to 80 percent of trip rating, then 0.80 X 15 = 12 Amps. 12 Amps X 120 volts = 1440 Volt-Amps per 15-Amp circuit. 1440 VA / 180 VA per receptacle = 8 duplex receptacles per circuit allowed.

For a 20-Amp circuit, you are allowed (.8 x 20 X 120)/ 180 = up to 10 duplex receptacles per circuit.

A good guideline many electricians follow as a 'rule of thumb' is of 1.5 amps per receptacle which is on the high end of the trip rating, but then again the trip rating is based off CONTINUOUS load. All of the inspectors I have had inspect my own electrical work in three different states has given the advice of no more than 12 receptacles per circuit. Switches are unlimited since they have no current draw.

Chances are 1Myke would be fine, but I would still map out all of the devices on the circuit. You never know what the circuit will already have on it, especially if it is an older home where previous rehabilitation may have taken place.
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post #9 of 14 Old 03-05-2013, 06:32 AM
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What else is already on that circuit? And what are you adding? You need to make sure that you know everywhere that circuit goes. Do not just assume, because someone else might have tied into it in the past.

That and what's already on it may also affect what you want to add. You'd want to avoid tapping into something that already has high-drain, or big in-rush starting current requirements. Like an AC compressor or fridge.
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post #10 of 14 Old 03-05-2013, 07:12 AM
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Quote:
Originally Posted by Mr.Tim View Post

There's no limit to the number of receptacles on a circuit in a US dwelling.

......

I didn't know that. I've seen TMcG's recommendation before, or at least something similar over the years. Perhaps I'm getting that confused with the 12 A limit on a 15 A breaker. Who knows.

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post #11 of 14 Old 03-05-2013, 10:15 AM
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Recommendations are fine.. When you build something to the minimum code standards it's really nothing to be proud of. Exceeding the code is something everybody should strive for.

I have 12 receptacles in my theater, which for the most part was the minimum to meet the spacing requirement. The chances that I'll ever use any other them.. Slim to none. I have central vac, so I won't even plug a vacuum into them. I don't know what I would ever plug into them. In that case, if I wanted to add 8 more just for convenience, it really wouldn't affect the load.

The code basically says use 180va per receptacle supplying equipment not secured in place, but then says general use receptacles in dwellings are not required to be calculated. (NEC 220.14(I)). They are specifically exempted by the code.

The 12a limit is imposed by 210.23(A)(1), which limits the load of cord-and-plug connected circuits to 80% of the ampacity, which is 12a on a 15a circuit. Of course, if you don't intend to plug anything in, you are using 0a. This is directed at commercial uses, where you are more likely to have designated equipment layouts.

Again, I wholeheartedly endorse exceeding code minimums, but as with many things, subject to practicality. That's exactly why I think it's a great idea to map the circuit out. Don't tap into something that is already at 80%

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post #12 of 14 Old 03-05-2013, 11:38 AM
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Quote:
Originally Posted by Mr.Tim View Post

Recommendations are fine.. When you build something to the minimum code standards it's really nothing to be proud of. Exceeding the code is something everybody should strive for.

Have you seen my autosignature?? biggrin.gif I didn't want to get too technical with my prior response by citing specific sections of the NEC, only to make clear the "rules of thumb" and high-level calculations in which many of the guidelines electricians use are grounded (pun intended!).
Quote:
Originally Posted by Mr.Tim View Post

I have 12 receptacles in my theater, which for the most part was the minimum to meet the spacing requirement. The chances that I'll ever use any other them.. Slim to none. I have central vac, so I won't even plug a vacuum into them. I don't know what I would ever plug into them. In that case, if I wanted to add 8 more just for convenience, it really wouldn't affect the load.

In this case exceeding code would actually mean LESS receptacles, not more, as the whole reason for limiting the potential number of receptacles is to prevent the risk of fire from circuit overload, wouldn't you agree?



We are all in perfect agreement that the circuit should be fully mapped out, that the junction be accessible and be done properly in a box which is really where our recommendations lie.
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post #13 of 14 Old 03-05-2013, 12:02 PM
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Less receptacles, and thereby more circuits would be exceeding the code. Which is a good thing, but should be tempered with practicality (which is why I mentioned my theater as an example, would I be better served with 2, 3, 4 circuits? In all practicality, no)

The limits being discussed are strictly design considerations.

The overcurrent protection device would address any potential safety concerns.

We are in absolute agreement. I am simply very careful about what the code says versus what is recommended. If he needs to put 13 receptacles, there is no code requirement to run a second circuit. My first reply was just a simple statement of fact, not a recommendation on how to proceed.

Tim
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post #14 of 14 Old 03-06-2013, 06:27 PM - Thread Starter
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WOW...thank you all for the respomces and advice. Its a new home and a 20A line i ran last year before even considering the theater so only 2 receptacles on it, and only used minimally. Therefore no load now unless i plug something into it. I want to run my 2 200w continuous power (500w max) subs now and possibly my emotiva 1000w amp. So basically 3 large items only, which could at most consume 17 amps on a 20A circuit !

I want to spit it so i dont have to destroy a lot of drywall, and can just run it in the opposite direction given the room layout.

It looks as though i'm fairly safe so thank you, i will ensure i use the proper box and cover to store the split!!

Thank you everyone

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