Making sense of different phases in panel


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Old 01-14-14, 02:25 PM
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Making sense of different phases in panel

Trying to make sense of the different phases of my panel in regards to some multiwire branch circuits my husband is trying to figure out.

The panel is 1-20
Breakers stacked like this:

1 and 2 phase A
3 and 4 phase B
5 and 6 phase A
7 and 8 phase B
9 and 10 phase A
11 and 12 phase B
13 and 14 phase A
15 and 16 phase B
17 and 18 phase A
19 and 20 phase B

If I have the following circuits sharing neutrals:
2 and 4, 3 and 5, 6 and 8, 7 and 9 and 18 and 19

Then those MWBC's are properly positioned and the neutrals would pass the difference of the loads rather than the sum. Hence, no overload but a proper MWBC setup.

Is my thinking correct?
 
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Old 01-14-14, 02:49 PM
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Yes your thinking and the positions are correct. If they had the required handle ties (or two pole breakers) then you wouldn't need to think about it because there would be no other way to get them into position. The 18+19 one is just waiting for the right person to come along and monkey things up.
 
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Old 01-14-14, 03:15 PM
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yes the 18/19 mwbc is what confused me enough to ask here.

No handleties in this grandfathered situation.

So even more confusing, say 2 and 15 were sharing a neutral.. even though they span the entire panel it still wouldn't be a code violation or something?
 
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Old 01-14-14, 03:17 PM
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If they had the required handle ties (or two pole breakers) then you wouldn't need to think about it because there would be no other way to get them into position.
Exception would be a GE panel with half size 240 breakers.
 
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Old 01-14-14, 05:44 PM
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Trying to make sense of the different phases of my panel
That's simple because there is only one phase, you have single phase power in the typical residential panel. What you have are two legs.

yes the 18/19 mwbc is what confused me enough to ask here.

No handleties in this grandfathered situation.
Your installation may be grandfathered, but moving the circuit from space 19 to space 20 would make things simpler to understand. I'd also suggest installing handle ties in all breakers on the MWBCs.
 
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Old 01-14-14, 05:48 PM
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Hence, no overload but a proper MWBC setup.
All ok except for 18/19. Don't split a MWBC like that. It's too easily confused.
Keep them stacked right above each other.
 
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Old 01-15-14, 04:45 AM
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I cant find General Electric handleties at the hardware store, does anyone know of a source?

My question remains too, in a MWBC do the breakers have to be on top of each other(directly or indirectly as in 18-19)? What about say 1 and 14? Same leg but far apart.

All ok except for 18/19. Don't split a MWBC like that. It's too easily confused.
Keep them stacked right above each other.
But technically safe, not an overloaded grounded conductor?
 
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Old 01-15-14, 05:12 AM
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The important thing is that the two hot lines of a typical multiwire branch circuit must be connected to breakers on different legs. You have it correct when you measure 240 volts between the two chosen breakers' terminals and you have 120 volts from each breaker terminal to neutral.

In your case, selecting breakers #1 and #14, both on leg A, is a no-no.

The rules work approximately the same with real 3 phase panels (there are three groups of breakers A, B, and C). There are some idiosyncrasies but you are safe when you make all three voltage measurements above and get all three correct. In most 3 phase panels with 120 volts and a very small number of "regular" panels with just A and B legs, you will measure 208 volts between legs instead of 240. The MWBC wiring is the same but you must be careful not to plug 120/240 volt appliances into 120/208 volt circuits or vice versa unless those appliances are rated for both 208 and 240 volts.
 
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Old 01-15-14, 06:25 AM
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I cant find General Electric handleties at the hardware store
A quick Google finds several on line sources (GE breaker "handle tie"). Remember though with GE half size it is possible to get both breakers on the same leg so if you just can't use full size test for 240 volts between the two breakers.
 
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Old 01-15-14, 01:31 PM
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Hi Ray, these are standard size GE breakers... might be harder to find??
 
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Old 01-15-14, 02:06 PM
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Home Depot has them on their website. This one should work.

GE 1 in. Single-Pole Handle Tie-THT104CP at The Home Depot

They also have them for the 1/2" thin Type THQP breakers if you need any.

GE 1/2 in. Single-Pole Handle Tie-THT1 at The Home Depot
 
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Old 01-15-14, 04:39 PM
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thanks just ordered a few. free ship to store, I bet they loose those small suckers before I get my hands on them.
 
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Old 01-15-14, 04:51 PM
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thanks just ordered a few. free ship to store, I bet they loose those small suckers before I get my hands on them.
hahahaha......I often wondered why they don't stock them since they are required to be used on MWBCs by code. I believe they may stock some Square D ties, but that's it. Maybe they just don't know what is commonly used and required and what should be stocked. I've wondered the same thing about main breaker hold-down kits for backfed main breakers and surge devices.
 
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Old 01-15-14, 05:02 PM
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I often wondered why they don't stock them since they are required to be used on MWBCs
All ordering is by computer the computer rejects any item not previously ordered by the store even though the warehouse stocks it. To get an item added the manger has to send a written request to Atalanta with justification for the need. From what I was told Atlanta looks at the computer generated forecasts for what the store is most likely to sell and rejects it. Stocking items that don't sell affects the bottom line and most importantly the managers year end bonuses.
 
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Old 01-15-14, 05:17 PM
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From what I was told Atlanta looks at the computer generated forecasts for what the store is most likely to sell and rejects it.
That kind of makes me wonder what qualifications the guy in Atlanta has. I can wander the electrical aisles in any big box and pick out at least a dozen items they really don't need to stock.
 
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Old 01-15-14, 05:36 PM
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You can find Square D and maybe Siemens handleties at the stores. The supply house in our area only carry Square D stuff.

I can get copper wire too and fashion a handle-tie from a bare piece of #12.... does that count?
 
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Old 01-15-14, 06:01 PM
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I can get copper wire too and fashion a handle-tie from a bare piece of #12.... does that count?
If done well, it should. The code requirement for two SP breakers protecting a MWBC is that they have "common disconnect." So whatever you can safely do to tie their handles together in such a way that turning either one off will flip the other one off will meet that requirement.
 
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Old 01-15-14, 06:06 PM
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I can get copper wire too and fashion a handle-tie from a bare piece of #12.... does that count?
If done well, it should.......................
 
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Old 01-15-14, 07:28 PM
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I have used a 4d casing nail if I recall correctly when there was a through hole in the handles.
 
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Old 01-15-14, 09:38 PM
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The "handle tie" will be at the inspector's discretion. Technically it needs to be a "listed' or "approved" handle tie and some hard-nosed inspectors will demand this. If yours does, then ONLY the handle tie from the circuit breaker manufacturer will be acceptable.

Myself, I have used a clipped drywall nail many times.
 
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Old 01-16-14, 06:11 AM
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The "handle tie" will be at the inspector's discretion. Technically it needs to be a "listed' or "approved" handle tie
I think that's the key. If the approved handle tie is available, that's what I'd use.
 
 

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