switch leg - shared neutrals


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Old 10-14-13, 05:15 AM
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switch leg - shared neutrals

If I hook up a switch leg to a switch where the hot (line) is on a different leg than the neutral at the light is that improper/dangerous?

This is on a subpanel with 2 - 20A breakers tied together, I assume that means this subpanel shares neutrals.
 
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Old 10-14-13, 06:18 AM
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If I hook up a switch leg to a switch where the hot (line) is on a different leg than the neutral at the light is that improper/dangerous?
If you have a multiwire branch circuit, you have two hot legs from the two hot legs feeding the panel and one neutral being shared for both hot legs. The neutral isn't on either leg and is used for both hot legs.
 
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Old 10-14-13, 06:38 AM
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Thanks.

Now what if it wasnt a multiwire branch circuit?

Hot going to switch on one breaker and neutral going back on different leg of panel.
 
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Old 10-14-13, 06:56 AM
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Now what if it wasnt a multiwire branch circuit?

Hot going to switch on one breaker and neutral going back on different leg of panel.
If it isn't a multiwire branch circuit, this circuit would be required to have it's own dedicated neutral. But, you earlier said.......

This is on a subpanel with 2 - 20A breakers tied together, I assume that means this subpanel shares neutrals.
This is a multiwire branch circuit. Again, the neutral is terminated to the neutral bus and is not on either leg of the incoming power.
 
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Old 10-14-13, 08:40 AM
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I assume its MWBC because the two breakers are tied together. I cant get in the fixture junction where the neutrals are, only switch boxes with just switch legs. If I only see one busbar in subpanel, is it safe to assume it is MWBC?

If it wasnt a MWBC, then there would be 2 bus bars right? One for each phase.

Garage breaker in mainpanel is 40amp, subpanel has 2x20A tied together.


Just for conversation sake, what are the ramifications of not having a dedicated neutral as described?
 
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Old 10-14-13, 09:31 AM
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If it wasnt a MWBC, then there would be 2 bus bars right? One for each phase.
Two busbars either way.

what are the ramifications of not having a dedicated neutral as describedj
Not sure what you are asking. Neutrals aren't dedicated, circuits are dedicated. Closest I can guess is you mean neutral and hot not in the same raceway (cable sheath or conduit). That can cause overheating of the wire.
 
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Old 10-14-13, 10:10 AM
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My inquiry is that I want to put 2 lights on one switch (pigtail the two switch legs).

If the switch leg and the neutral are in the same conduit, is that ok to do?
What do I have to assure before doing this?

I must be missing something....
 
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Old 10-14-13, 04:16 PM
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Are you saying that you currently have one light on each switch and now you want to move them both to one switch ? That sounds do-able.

If there is only one white wire at that location then they are using the same neutral already.
 
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Old 10-14-13, 05:46 PM
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The thing is there are no neutrals in the switch box. They are in the junctions in the ceiling that are not readily accesible.

What do I have to assure is correct before pigtailing the two switchlegs to one switch?

Is it safe to assume this is a MWBC just because this is a subpanel with two breakers tied together?(not a double pole, 2 singles with handle tie).
 
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Old 10-15-13, 06:10 AM
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Let me ask this way.

Is it ok to power 2 seperate lights from one switch by pigtailing the switch legs and using the same hot?

The two lights are not connected to each other and could be on seperate circuits right now.
 
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Old 10-15-13, 09:39 AM
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A possible solution--but let the experts weigh in on if it's code: Wire the 2 black switchlegs to a 2-pole switch and label the junction box for dual power sources.

Also--I may have missed it--is this tie-bar breaker a 1/2-width dual on ONE phase, or 2 full-width breakers straddling BOTH phases?
 
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Old 10-15-13, 07:37 PM
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You may not feed the light using the hot wire from one cable going back to the panel and the neutral from a different cable going back to the panel.
 
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Old 10-16-13, 03:59 PM
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The thing is there are no neutrals in the switch box. They are in the junctions in the ceiling that are not readily accesible.
You may have to open the ceiling boxes to nail this down, but let's see what we can figure out without doing that.

How do you know there is no neutral in the switch box? Describe the wiring in the box, please.

What do I have to assure is correct before pigtailing the two switchlegs to one switch?
That the two switches are fed from the same leg of your service.

Is it safe to assume this is a MWBC just because this is a subpanel with two breakers tied together?(not a double pole, 2 singles with handle tie).
No. Uncover the subpanel and trace the wires from the two breakers to where they leave the panel enclosure. Then trace all other wires that are in the same conduit or cable with those two wires down to their termination points inside the subpanel. Tell us what you find.

Also tell us whether the subpanel has two busbars in it, as Ray noted - a bonded one for the grounds and an isolated one for the neutrals.

This may give us enough information to go forward with.
 
 

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