Need advice about installation NEMA 14-50

[eprosenx]

So, that is what I thought to do. Last two 15A breakers out, one tandem breaker and 50A two poles breaker in. Will cut a hole for the box on a vertical surface of a shelf bellow (still do not know if it is a plywood or sheetrock, probably does not matter). Generally nothing really complicated, just want to make it reliable. That hose under a bit on a way though...
Also the box on a right wall, close to the gate, so charging cable will lie on a car...

Make sure to get a beefy double gang box to install a NEMA 14-50 in. They make "range boxes" for this purpose. It needs to be secured very well. I surface mounted mine just so I did not have to deal with it. Home Depot sells an Eaton surface mount box that is better than the one I got. Though even the Eaton one does not have the Tesla recommended heavy duty receptacles from a couple of manufacturers they think make robust receptacles.

 

[eprosenx]

Thanks was referencing this chart http://www.eaton.com/ecm/idcplg?Idc...eased&Rendition=Primary&&dDocName=SA00304001E

Ah yes, so I missed that what you linked to was a "Homeline" breaker. Yeah, those seem to be the same form factor as many other manufacturers.

Though with that being said, that document you linked to says that Eaton has gone to the expense of having their breakers cross-certified to replace other manufacturers breakers. That does *not* mean that the other manufacturers breakers are certified in Eaton panels or in other manufacturers panels that appear to be identical... (they probably would work, but I personally would want the right ones since they are only a few bucks).

I think this is the breaker you want:

Murray (2) 15 Amp Tandem Single Pole Type MH-T Circuit Breaker-MP1515U - The Home Depot

I don't know why there is a "U" at the end of this SKU. I have not been able to figure out what the "U" means. Pretty sure it is the right breaker though. It may have something to do with "universal" or something. NEC back like before 1968 did not have the "keying" requirement for tandem breakers, but then they did, and now again I think they have removed it, so I don't know if that means the manufacturers are just removing the keying requirement on all the breakers they sell?

They make this one that was specifically only for replacement use in panels prior to 1968 that did not have the notched keying, but were allowed to have tandem breakers:

Murray 15 Amp Tandem Single-Pole Type MH-T NCL Circuit Breaker-MP1515N - The Home Depot

Oh, and you will want one of these:

Murray 50 Amp Double-Pole Type MP Circuit Breaker-MP250 - The Home Depot

 

[eprosenx]

Oh good. Though are you positive? I am very suspicious since you have a bunch of red wires in your panel. Normally I only see red wires when they are in a sheath with another black wire (shared neutral).

Oh, the red wires are on the left side. You are talking about swapping a breaker on the right. Got it. Those are all black in the bottom right.

 

[eprosenx]

@eprosenx how to u like that Sense monitor? Was thinking of getting one but still somewhat pricey

I *love* my Sense monitor.

The machine learning and device identification leaves a *lot* to be desired... But the real time and historical graphing is fantastic. I love being able to see what my house is doing! Great way to keep track if your appliances are working properly or not. Lots can be gleaned from the data. It was very educational to learn what different things in the house draw.

 

[BestHand]

Oh good. Though are you positive? I am very suspicious since you have a bunch of red wires in your panel. Normally I only see red wires when they are in a sheath with another black wire (shared neutral).

eprosenx, Sorry I misunderstood you. Of course red and black wires have shared neutrals. But I can not understand how it makes any difference. All white neutral wires connected to the same bus, all hot (red and black) wires connected to separate breakers anyway. With tandem breaker both connected wires still will have separate breakers (tandem breaker has two breakers connected to the same hot bus). Do you mean that by code all red wires supposed to be on one bus and all black wires on another? On a left side (all 20A breakers) all red connected to one bus and all black wires connected to another, but on a right side most wires are black and it means that half of them connected to one bus and other half connected to another bus. I think it does not matter until some hot wires are connected somewhere in a house.

 

[eprosenx]

eprosenx, Sorry I misunderstood you. Of course red and black wires have shared neutrals. But I can not understand how it makes any difference. All white neutral wires connected to the same bus, all hot (red and black) wires connected to separate breakers anyway. With tandem breaker both connected wires still will have separate breakers (tandem breaker has two breakers connected to the same hot bus). Do you mean that by code all red wires supposed to be on one bus and all black wires on another? On a left side (all 20A breakers) all red connected to one bus and all black wires connected to another, but on a right side most wires are black and it means that half of them connected to one bus and other half connected to another bus. I think it does not matter until some hot wires are connected somewhere in a house.

Great question!

So it does not matter that all "reds" have to be on the same bus and all "blacks" have to be on the other bus. That is not a rule. What is SUPER critical is that for a given "multi wire branch circuit" (which is what NEC calls it when you have a "shared" neutral), the two "hot's" (one red one black typically) MUST be connected to opposite phase busses. The reason for this is that those two busses are 180 degrees out of phase and so the neutral loads will cancel each other out if equally loaded. If you accidentally hooked both hots to the same bus in the main panel you could have DOUBLE the rated load on the neutral and melt it (starting a fire) without tripping the breakers.

So when consolidating wires up to the tandem breakers a common mistake is taking two adjacent breakers feeding a multi-wire branch circuit and consolidating them onto a single breaker which is fed from a single bus.

As long as you keep them connected to opposite phase legs you will be golden! You can still use tandem breakers, but you just have to be careful which goes where...

 

[P85_DA]

@eprosenx just out of curiosity ..based on his pics the consolidation is happening in same side (bus) that would be ok ? ...reason asking is I’m about to do something similar at my other house ..thanks for the great feedback

 

[eprosenx]

@eprosenx just out of curiosity ..based on his pics the consolidation is happening in same side (bus) that would be ok ? ...reason asking is I’m about to do something similar at my other house ..thanks for the great feedback

In a hurry right now so don't have time to go find you a picture, but the gist of it is this:

The two busses are not the left side and the right side. They are actually alternating pole positions on opposite busses. So every other breaker (regardless of left or right side of the panel) is on an opposite bus (in three phase they alternate 1,2,3 1,2,3 1,2,3). That is why single wide breakers are 120v (phase to neutral voltage) and double wide breakers (in residential applications) are 240v (phase to phase voltage)...

Does that make sense?

 

[BestHand]

Okay, as long I did not change existing phase of the wires I will be Okay. I got it. To do it this way I should shift more than just one breaker, or use two tandems I guess. I have to draw the simple picture on paper, so it will be clear.

 

[eprosenx]

Okay, as long I did not change existing phase of the wires I will be Okay. I got it. To do it this way I should shift more than just one breaker, or use two tandems I guess. I have to draw the simple picture on paper, so it will be clear.

Yup. Just make sure that any shared neutral circuit is across two separate phase legs and you will be good. Even if you have to move around a third circuit in order to make this happen it is generally pretty easy.

 

[BestHand]

Thanks, I will be fine. Never thought about possible overload of neutral wire. Good tip.

 

[BestHand]

BTW, I noticed that on a right side of the panel (all 15A breakers except A/C) all wires are same black color, as on a left side every other. So where are the red ones? Answer is easy: red wire were not in use and been cutted. So I should not even worried about sharing the neutral, as only one wire used as hot in these circuits.
Thank you all.

 

[eprosenx]

BTW, I noticed that on a right side of the panel (all 15A breakers except A/C) all wires are same black color, as on a left side every other. So where are the red ones? Answer is easy: red wire were not in use and been cutted. So I should not even worried about sharing the neutral, as only one wire used as hot in these circuits.
Thank you all.

Generally if the wire will not be a "multiwire branch circuit" electricians just run wire with NO red wire in it. Copper is expensive so they don't just waste it. ;-)

 

[BestHand]

Of course, why use 3 wires when you can use 2 wires cable. But when I checked today I saw red wires cutted next to the entry clams.

 

[mongo]

Generally if the wire will not be a "multiwire branch circuit" electricians just run wire with NO red wire in it. Copper is expensive so they don't just waste it. ;-)

Another issue is that shared neutral circuits should be on a two pole breaker (required since 2008, good idea in general). NEC 210.4 This can be fixed with handle ties.

Also (not relevent to this breaker box), the circuit cannot use an outlet to maintain the neutral connection, must be a pigtail 300.13(B).

 

[mongo]

General comment.
I count:
11 neutral wires
6 red/black wire 'pairs?' (on non paired breakers)
1 black/black pair for AC compressor (two pole breaker)
5 single black wires
Total of 12 circuits, so does one not have a neutral (possibly the AC)?

I'm also not seeing many ground wires. @BestHand , would you mind taking a more zoomed out interior photo?

 

[eprosenx]

Another issue is that shared neutral circuits should be on a two pole breaker (required since 2008, good idea in general). NEC 210.4 This can be fixed with handle ties.

Also (not relevent to this breaker box), the circuit cannot use an outlet to maintain the neutral connection, must be a pigtail 300.13(B).

Great info! And thank you for citing the code sections! I had heard this might actually be a "thing" now, but I had not yet found it in the code. I will have to go read up on that.

I suppose the concern here is that you turn off one of the two (or three) hot conductors in a multiwire branch circuit and you assume the neutral is also dead. But say the neutral is loose elsewhere and the other hot (or hots) are still carrying current, then that neutral may also have potential (be hot) relative to ground.

I wonder if you are working in an existing box and consolidating circuits if inspectors would require the handle ties? Can you get handle ties that go from a "tandem" breaker to another "tandem" breaker across the gap? Or what about a "tandem" to a non-tandem?

When I build my next house I think I am going to put in the spec that the electricians can't use multiwire branch circuits since I just don't want to deal with this. ;-)

A Serious Decision | Electrical Contractor Magazine

 

[mongo]

Great info! And thank you for citing the code sections! I had heard this might actually be a "thing" now, but I had not yet found it in the code. I will have to go read up on that.

I suppose the concern here is that you turn off one of the two (or three) hot conductors in a multiwire branch circuit and you assume the neutral is also dead. But say the neutral is loose elsewhere and the other hot (or hots) are still carrying current, then that neutral may also have potential (be hot) relative to ground.

I wonder if you are working in an existing box and consolidating circuits if inspectors would require the handle ties? Can you get handle ties that go from a "tandem" breaker to another "tandem" breaker across the gap? Or what about a "tandem" to a non-tandem?

When I build my next house I think I am going to put in the spec that the electricians can't use multiwire branch circuits since I just don't want to deal with this. ;-)

A Serious Decision | Electrical Contractor Magazine

The main concern is turning off one breaker but having live wires in the outlet/ box. Multiwire is great for combo outlets like disposal and dishwasher or washer and dryer. But yeah, for regular outlet feeds, it is more cumbersome.

The make tandem two pole breakers with paired inner and outer handle sets (in some brands).

Depending on the AHJ, existing stuff gets grandfathered, otherwise need arc fault breakers/ outlets also..
Mike Holt forum is great for this stuff...