Help with split bus panel

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Old 01-28-14, 03:05 PM
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Help with split bus panel

I have a split bus panel that appears to have two/four open spots to it, but after looking at the diagram inside the door I'm confused. I'd like to add a 240v circuit for a compressor/welder and a few 20amp outlets in the garage. Could someone wiser please look over these pictures and tell me if the open spots are truly open?

Thanks in advance.



 
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Old 01-28-14, 04:38 PM
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Welcome to the forums!

We'll need more information to form an opinion: What is the make and model of your panel? What does it look like with the cover on? What is listed on the panel schedule?

At a glance it appears that slot 12 may be available. That said, I don't see the 2-pole 70A "lighting" main - but it must be there.
 
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Old 01-28-14, 05:01 PM
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The lighting main does appear to be missing.
 
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Old 01-28-14, 06:01 PM
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The panel is an ITE EQC5X12B - house was built in '79 if that helps.

Positions 1, 10, and 11 feed the stove, dryer, and A/C. Position two is a dual pole 50amp (100amp total?) feeding the remaining lower breakers - it looks like it's physically wired down to the bottom of the busses for the single pole breakers at the bottom? The lower breakers are only vaguely labeled. Most say "appliance", except for a few that have been hand labeled over the years.

There isn't anything in the spot for the lighting main, I'm assuming the breaker above is serving that purpose? Have I got a mess?

Pic below of panel with cover - thanks again for your help.

 
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Old 01-28-14, 06:22 PM
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Position two is a dual pole 50amp (100amp total?) feeding the remaining lower breakers
That's your lighting main, but I am wondering, 1.) why it is one space higher than the panel diagram shows? And 2.) the diagram shows a 70 amp breaker for the lighting main and your is a 50 amp, what happened? Can you tell if the aluminum stabs where the lighting main should be have been damaged by inspecting it? It appears to me that you could install up to two 2 pole breakers, but I cannot inspect the entire panel from here.
 
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Old 01-28-14, 06:32 PM
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The stabs appear to be untouched - no scratches or signs that they've ever been used. We have lived here with four people for about 6 years and have never tripped the 50 amp breaker, so I guess it's sufficient (or ancient and not working).

I think that the wiring is original and unmolested since the house was built. It's all relatively neat, and there hasn't been any additions or major renovation of the house.

One more thing I was wondering about: All the lower breakers are 20amp, and all the wiring is black and red instead of black/white. Is this common in older wiring, or has someone wired my entire house with 20 amp, 12ga circuits?
 
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Old 01-28-14, 06:40 PM
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All the lower breakers are 20amp, and all the wiring is black and red instead of black/white. Is this common in older wiring, or has someone wired my entire house with 20 amp, 12ga circuits?
First, the wiring is all copper, isn't it? Are any of the branch circuits aluminum? If the breakers are all 20 amp, the wiring, if copper, would all be 12 gauge. The black and red conductors to the single pole breakers tell me those are multiwire branch circuits which share a common white neutral wire (from a 12-3 w/G cable). The black and the red from a single cable should be fed by opposing busbars in the panel, otherwise the neutral could become overloaded. I think I'd check that out on the left side of the panel where it appears there are tandem breakers.

A tandem is 2 breakers in a single case, each pole gets power from the same bus stab.

The closer I look at the panel diagram, the more I am thinking that panel shouldn't have any tandem breakers in it at all. It's a 100 amp panel, right? Without tandems it would have a total of 26 spaces. 26 spaces was a very big 100 amp panel back in the '70s, I don't think those tandems should be there.
 
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Old 01-28-14, 07:15 PM
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Everything is copper. No aluminum anywhere in the panel, including mains.

The black and the red from a single cable should be fed by opposing busbars in the panel, otherwise the neutral could become overloaded.
I'll have to pull the cover back off to check, now I wish I'd taken a better picture.

I swear one of these days I'm going to build a new house and get away from this weirdness. Our first house had screw-in fuses, cloth wrapped wire, and no grounds. I guess I'm slowly getting closer to modern.
 
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Old 01-28-14, 07:16 PM
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Position 2 can be freed up by moving the "lighting" main down to the unnumbered pair of spaces opposite position 12. That should be done. Then you can use either position 2 or position 12 for the 240V circuit you want to add.

It appears that you have 6 standard-height spaces available on each side for 120V breakers, that each of those spaces is rated to take a tandem breaker if desired, and that only 5 of those spaces on each side are occupied. If so, there appears to be space available for up to 4 new 120V circuits.

All the lower breakers are 20amp, and all the wiring is black and red instead of black/white. Is this common in older wiring, or has someone wired my entire house with 20 amp, 12ga circuits?
Not sure what you're asking.

Black and red have been the common colors for conductors carrying ungrounded potential (hot wires) for decades. The white conductors for grounded potential (the neutral wires) appear to be terminated to neutral buses in the back, outer edged of the enclosure. This is as it should be. A white wire should only be used to carry ungrounded potential in certain very limited circumstances.

If a circuit are protected at 20A then they should be wired with 12AWG copper conductors or 10AWG aluminum conductors. That's also been true for decades, and has nothing to do with the color of the insulation.

Before you dive into this project, buying and reading a copy of the text for our little online seminal would probably help you understand more about how residential wiring works. It's called Wiring Simplified, and it's authoritative, up-to-date, readable and inexpensive. You can often find a copy in the electrical aisle at a large home improvement stores.
 
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Old 01-29-14, 05:54 AM
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Your lighting main in the second double position from the top left can stay there. The third double position from top left is the suggested position for the lighting main. (Or the panel came from the factory with a breaker set as a lighting main already in that position.) You can put a breaker for something else there now.

The sum of the amperages of the top 3 breakers in both columns combined (as 240 volt double-wide doubles) may not exceed the panel amperage rating.

There is a limit to the number of breaker handles in the panel. If you have several single wide double breakers (tandems) in the panel, you may exceed the permissible number of handles before you filled all the slots.
 

Last edited by AllanJ; 01-29-14 at 06:11 AM.
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Old 01-29-14, 10:33 AM
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It appears that you have 6 standard-height spaces available on each side for 120V breakers, that each of those spaces is rated to take a tandem breaker if desired, and that only 5 of those spaces on each side are occupied. If so, there appears to be space available for up to 4 new 120V circuits.
I disagree and would like to see more of the panel label/labels. Based on the panel diagram, I don't believe this panel was ever intended to have tandem breakers in it. I believe there are two spaces left at the bottom of both the left and right sides of the lighting section.

The sum of the amperages of the top 3 breakers in both columns combined (as 240 volt double-wide doubles) may not exceed the panel amperage rating.
Where do you get this?
 

Last edited by CasualJoe; 01-29-14 at 10:56 AM.
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Old 01-29-14, 01:07 PM
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The sum of the amperages of the top 3 breakers in both columns combined (as 240 volt double-wide doubles) may not exceed the panel amperage rating.
Why? Is there something unique about this panel that the rest of us haven't spotted?
 
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Old 01-29-14, 01:18 PM
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The closer I look at the panel diagram, the more I am thinking that panel shouldn't have any tandem breakers in it at all...

I disagree and would like to see more of the panel label/labels. Based on the panel diagram, I don't believe this panel was ever intended to have tandem breakers in it. I believe there are two spaces left at the bottom of both the left and right sides of the lighting section.
Good call.

Now that I look at the diagram again, it looks to me like this panel is designed to hold up to six 240V breakers including the lighting main, up to ten full-height 120V breakers, and up to two 120V tandem breakers, in positions 8 & 9, and 18 & 19. That's a limit of 14 120V circuits total, as I see it now.

It looks like there are 19 120V circuits in it already.
 
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Old 01-29-14, 06:48 PM
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up to ten full-height 120V breakers, and up to two 120V tandem breakers, in positions 8 & 9, and 18 & 19
No, I don't think so. This is a rather strange diagram though. Look again, spaces 8, 9, 18 and 19 are all fed by the same leg, the "B" leg. I don't see anything that looks like those spaces will accept tandems. I'd still like to see more of the label and I'd also like to see a lower picture without the panel cover that shows those lower stabs a little better. I really don't think there is a notch in them to allow tandem breakers and this panel isn't old enough to be a non-CTL panel, I believe it would have to be a pre-1968 panel for that.
 
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Old 01-29-14, 08:32 PM
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We'll see. I agree, we need those other images to help figure it out. That said,
This is a rather strange diagram though. Look again, spaces 8, 9, 18 and 19 are all fed by the same leg, the "B" leg. I don't see anything that looks like those spaces will accept tandems.
Yes. I see that they're fed by the same leg. To me that just indicates that they're only good for 120V circuits. I still think that those 4 (or 2) spaces are rated for tandems and the other 10 aren't, based on the drawing.
 
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