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Old 12-14-2011, 12:04 AM   #1
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Why run multiple in's and outs in one box?


One outlet / box, two lines in, two lines out.

WHY???

Either add another box, or don't.

My basement was rewired probably 10 years ago, and I'm about ready to redo it just because of how stupidly it's setup. They have one box with two lines running in and three lines running out - each line controls HALF an outlet. Whether or not this is to code, it's dangerous as , because when a breaker turns off an outlet, you expect it to turn off the entire outlet, not the first plug.

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Old 12-14-2011, 12:26 AM   #2
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Why run multiple in's and outs in one box?


Split receptacles with 2 circuits are required to have a handle tie, so all ungrounded conductors are disconnected at the same time

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Old 12-14-2011, 05:51 AM   #3
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Why run multiple in's and outs in one box?


Quote:
Originally Posted by Techy
Split receptacles with 2 circuits are required to have a handle tie, so all ungrounded conductors are disconnected at the same time
Believe that's inaccurate, you only need a handle tie only if it's a mwbc
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Old 12-14-2011, 06:59 AM   #4
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Why run multiple in's and outs in one box?


Did it look like those receptacles were wired that way from day one as opposed to modified several years later to have the multiple ins and outs?

Let's take it step by step (hypothetical as opposed to practical argument).

1. Think of a multiwire branch circuit (shared neutral) with separate hot feeds for each half of the duplex receptacle.

2. The hot wires are on the same side (leg) of the 120/240 volt service so separate neutrals are needed.

3. Presto, you got what you got.

4. Similar situation, two single switches each fed with a switch loop from a different light fixture, replaced with a duplex switch unit.

By the way, with the separate neutrals, the tab between the side screws must be broken off on the neutral side of the duplex receptacle unit as well as on the hot side. Neutrals accompanying hot wires coming from different directions, must not be combined downstream*

And, by the way, if not required then it would at least be a good idea to have the two respective breaker handles linked together. It is okay to use a double wide double breaker to feed these two circuits. Also a single wide double breaker (tandem breaker) if its handles can be linked.

* I suppose you must make an exception when separate Romex cables from the same switch box all one circuit serve light and fan in a unit with black, blue, and only one white conductor(s).
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Last edited by AllanJ; 12-14-2011 at 07:09 AM.
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Old 12-14-2011, 11:11 AM   #5
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Why run multiple in's and outs in one box?


There are situations where there must be two or more separate circuits in the same electrical box.

or...

There are situations where there are two or more separate circuits in the same electrical box. (Does not have to be that way, but it is!)

In either case, if you are not familiar with the way things are wired and not 100% sure what is what, then as a rule you should ALWAYS turn off the main breaker before servicing anything.

Then you will be sure all the circuits are off.
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Old 12-14-2011, 11:31 AM   #6
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Why run multiple in's and outs in one box?


Always test every wire in a junction box for voltage before sticking your paws in there. I have a few JBs in my home with multiple circuits (not MWBCs). Some I inherited when I bought the house; one or two I've added for practical reasons (such as breaking an original circuit into two separate circuits, or expanding an existing switch box to accomodate more devices).

That being said, if you don't like your current setup and want to change it within code, you are free to do so.

In real-world practice, it's never safe to assume that a single breaker controls multiple cables in a junction box; use a volt meter to check.
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Old 12-14-2011, 11:49 AM   #7
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Why run multiple in's and outs in one box?


When I run into this, I like to write all the applicable circuit numbers on the back of the box cover plate.
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Old 12-14-2011, 12:01 PM   #8
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Why run multiple in's and outs in one box?


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When I run into this, I like to write all the applicable circuit numbers on the back of the box cover plate.
+1

I just split a circuit into 3 separate circuits. I did exactly this; I'm glad others are doing so and recommending it as well.
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Old 12-14-2011, 05:07 PM   #9
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Why run multiple in's and outs in one box?


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Originally Posted by Julius793 View Post
Believe that's inaccurate, you only need a handle tie only if it's a mwbc


NEC 210.7, all ungrounded conductors supplying devices on the same yoke must be simultaneously disconnected
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Old 12-14-2011, 05:32 PM   #10
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Why run multiple in's and outs in one box?


Quote:
Originally Posted by Julius793 View Post
Believe that's inaccurate, you only need a handle tie only if it's a mwbc
Wouldn't a spilt plug be considered a MWBC, unless someone ran 2 two wires to it then it would not be.
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Old 12-14-2011, 05:40 PM   #11
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Why run multiple in's and outs in one box?


I think the intention of that tie-bar rule is that if a maintenance person or other person is replacing a device like an outlet, and that outlet has two separate circuits on it (2 breakers), then they must have a tie-bar so both must be turned off at the same time.

Then the maintenance person is safe.

More common for someone to replace an outlet - homeowner, maintenance person, or other non-electrician.
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Old 12-14-2011, 05:51 PM   #12
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Why run multiple in's and outs in one box?


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Originally Posted by Billy_Bob View Post
I think the intention of that tie-bar rule is that if a maintenance person or other person is replacing a device like an outlet, and that outlet has two separate circuits on it (2 breakers), then they must have a tie-bar so both must be turned off at the same time.

Then the maintenance person is safe.

More common for someone to replace an outlet - homeowner, maintenance person, or other non-electrician.
That makes sense. What would have made a lot more sense just to use two separate boxes.

Flipping the main breaker is kind of a pain in the ass - no light to work, gotta reset a bunch of stuff. I'm going to try and undo some of the really screwed up stuff, just sucks they did it this way to begin with.
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Old 12-14-2011, 06:21 PM   #13
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Why run multiple in's and outs in one box?


Before you do any rewiring, learn what a MWBC (Multi-Wire Branch Circuit) is and learn about its dangers.

Search google.com for the words...
multiwire branch circuit

I don't know if you have that or not. These are common for garbage disposal/dishwasher outlets, but can be elsewhere.

Also might be a good idea to take pictures of the existing wiring and label the wires (for yourself) so you know how things were wired.
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Old 12-14-2011, 06:27 PM   #14
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Why run multiple in's and outs in one box?


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Wouldn't a spilt plug be considered a MWBC, unless someone ran 2 two wires to it then it would not be.
Depends on whether a shared neutral is used or not. You *could* split both tabs on the recept and wire each hald to separate circuits.
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Old 12-14-2011, 09:11 PM   #15
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Why run multiple in's and outs in one box?


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Depends on whether a shared neutral is used or not. You *could* split both tabs on the recept and wire each hald to separate circuits.
Guess you didn't read my whole post, that is exactly what I said.

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