Panel Wiring breakdown.

Looking to rewire my house/breaker panel. There was a kitchen remodel before I bought the house so some circuits were updated to romex but for the most part nothing is grounded, I am finishing the basement and want to update wiring throughout the house as part of the process. I will likely reorganize the panel in the process as it is mislabled and there are 220 circuits running nowhere. House was built in 1950, 100 A service, square D panel.
The 2 breakers connected with a wire for 220 center right goes nowhere so that will be removed for 2 more 110 breakers, the 220 breaker on the left is split to 110 for the sump pump so that will free up a slot as well.



As you can see I do not have any more slots available to add to the service, can someone decipher this diagram? can I add tandem breakers here? not sure I follow the 1 1r 3 3r 5 5r, etc. and should the double pole breakers be in slots 2-4 6-8 and 10-12?





Gas Range and gas dryer so I should have plenty of power, its a pretty small house. If I have the space available I would also really like to make a 220 slot for backfeeding power from my generator when the power is out.

 

Also, there are three neutral/ground bars on top of the panel, the furthest one back only has one ground wire ran to it, the other two have ground and neutral wires run to both of them and the bars themselves look to be connected, I understand this is normal. The front two bars have a number of holes with 2 or 3 wires in them, any advise related to this when rewiring the box?

 

It appears as though you can use tandem breakers on all of the left side positions and in the two bottom positions on the right. This is a strange one, I have never seen a Square D panel quite like this one. From the diagram it also appears as if positions 2-4, 6-8 and 10-12 are for 2 pole breakers, but I have never seen or heard of a situation like that with a Square D QO panel. I see no harm in using 1 pole breakers in those positions. On the neutral bar, you should not have more than 1 white neutral conductor per hole, but it is OK to have as many as 2 ground wires in the same hole as long as they are the same size. If you need more holes on the neutral bar, add a separate ground bar for the ground wires to free up a few more holes.

 

Thats what it looked like to me as well but I had not seen a diagram quite like this one, any idea what the r represents in the 1r 2r etc?

 

Older Square D tandems used to have the two handles side by side. The newer ones are one over the other.

It may be easier to find an interlock for a newer design panel. The breakers will transfer over.

BTW, it is 120 and 240 volts.

 

I have no idea what the "R" means. Here is what the old style Square D QO tandem breakers used to look like. At the link scroll down to 2nd picture.

Inspecting Tandem Circuit Breakers - aka 'Cheaters' | Structure Tech Home Inspections

 

That's a piggyback breaker. Wanna really squeeze a panel? Fill it with tandem piggybacks!

The "R" is for "Right" - for the piggyback handle to the right, I'm guessing.

 

nevermind, I should've read the OP more closely..

 

Nashkat1 - makes sense, thanks. CasualJoe, I have skimmed through that article but at the time I was not sure what applied to my situation.

pcboss - what is involved installing (or having installed) an interlock from a newer panel?

Thanks for all of the replies

 

Googled the interlock, seems like a decent alternative to a transfer switch. Just to clear this up in my head, are you calling it a "piggyback" breaker because it is a tandem, or because of the style of tandem? How is the left/right style tandem different from the top/bottom tandem? And what is the consensus on tandems? I would look to add probably 4 circuits if I kept the generator backfeed in the plan.

 

Tandems are just a way of fitting more circuits in a panel. Not all panels can use them. Yours can use them.

 

I thought that at first too, but if you look at the panel diagram, that theory only works on the right side of the panel. On the left side of the panel, the "R" handles are the left breaker handle.

 

Yeah, I know. It was a guess. Still is, as far as that goes - I'm not convinced the diagram indicates which handle is which on this strange old panel. But that's cool... whatever.

Got another theory?

 

I was just saying you will be able to find an interlock for a newer panel easier than the panel you have.

The arrangement of the tandem breakers makes no difference. They both allowed two circuits in the space of one.

 

Good point, pcboss. I would bet that Square D does not make an interlock cover for these old panels. The alternative would be a universal interlock from a 3rd party manufacturer which normally are NOT U.L. Listed.