While reorganizing an older Murray panel (Brooklyn era) and replacing a few older breakers with the current MP style I found they do not fit over the tabs on positions 9, 13 and 17.
The tab width on these are approx 3/4-7/8". I also noticed some burrs and some copper looking marks at the ends, is this normal and safe to use with the correct breaker.
Thanks In advance to all.
Someone (Bruce Banner?) tried to fit incompatible breakers such as GE THQP215 or a double-stuff Murray MP2020U. Breakers that Just Don't Belong in this panel.
When the breaker didn't fit, that person just "made it fit". And bent the bus stabs all to heck. You've circled the faults, but I would pop the other breakers and check them too.
I really, really, really, really do not like damaged bus stabs. If you look at the history of panels that have had severe problems (Zinsco, FPE) the real firestarter in the panels is their faulty bus stabs, and that can't be fixed by changing breakers. So bus stab damage should be treated "serious as a heart attack".
The affected spaces are 9-10, 13-14, and 17-18. The even numbered spaces aren't making good contact either, so you cannot continue them in service as-is. That means the 2-pole breaker in 16+18 can only go in spaces 1-8 now.
I suppose you could shut off the main breaker, test that it has no leakage, and get in there and straighten the breakers, and pray to the metal-fatigue gods that you haven't weakened them in the bend-unbend. Not easily will they bend; the last guy really did a gorilla job on this thing.
However, I also see what look like "burrs" on there, most acute on the one above the top red circle. I can't even fathom how a breaker would do that damage, unless it was arcing. (which is of course the danger). That's a harder fix; that'll require getting in there with a light file and dressing that back to proper shape as far as possible, but that'll require someone with some chops at metalwork. if you scratch up the sides of the stabs, you'll create an arcing problem.
Who knows what other damage is under breakers 1-8?
Separately from that, this is a 20-space, which is small even for an apartment, which I suspect is how this all started. Some chowderhead decided to pound in double-stuff breakers, even though the label plainly prohibits them.
But the failure tree branches back further, to the person who saved the cost of a latté by speccing such a small panel. Spaces are cheap when you're buying a panel.
This. This is why on this stack we veritably foam at the mouth to say "get a HUGE panel". Because then, stupid doesn't happen.
Fortunately, this panel is in a "utility space": it's surface mounted, so you won't be fighting drywall. There are two ways to go on replacing this panel, depending on logistics.
Option 1: Double-barrel panels. if you have the space, fit another service panel right next to it. I would go at least a 30-space. (no more double-stuffs, 'K? They're effectively illegal now anyway.)
Feed the new panel from a big breaker (or subfeed lugs) in the old panel. Move circuits to it at your leisure. As discussed, spaces 9-10, 13-14, and 17-18 are unusable; and they're all on the same phase. Ignoring your 240V breakers, you now have 8 spaces on phase 1 but only 2 on phase 2. So effectively, you can't use spaces 9-20 at all, and should migrate away from them ASAP. They really chowdered this panel.
Option 2: Replace main panel. Again, being in utility space saves you, but you'll need to have the power company cut power. Fortunately, you are in conduit, where you can just go to the other end of the conduit and pull the wires back to protect them during all the metal-flinging.
I would replace with a 40-space panel. Staying with Murray/Siemens is perfectly fine, it's a good panel and it'll let you reuse the breakers. 40-space because the next size down is 30, and that's too few. If physical space is an issue, look at Eaton CH or the overpriced Square D QO which are more compact (without being double-stuffed).
If your panel was more glued into the wall and had more cables and less conduit, I would propose swapping the bus assembly with another panel with the same mounting hole and cover form-factor; or simply going with one of the Eaton kits that lets you replace all the panel guts. (it's intended for Zinsco/FPE panels). But that's excessive here.
I see a couple red wires in there, and I see more hots than neutrals. Your panel should be labeled to show which neutrals go with which hots. I suspect you will have cases where 2 hots share a neutral, which is called a Multi-Wire Branch circuit or MWBC. In that case, the 2 hots must be on a 2-pole breaker such as the one in 16-18.
If this is done, the neutral will carry only differential current (e.g. if one leg draws 10 amps and the other draws 15, the neutral will carry 5 amps). If they are improperly placed, the neutral will draw the sum (25 amps).
Look at breakers 11 and 15 (or 15 and 19?) They appear to be an MWBC. Danger! Their breakers cannot be positioned like that, or they will overload the neutral. Losing most of your phase-2 positions makes it impossible to place MWBCs correctly in this panel.
If you cannot fix the MWBC problem any other way, then you need to place both hot wires on the same terminal of the same 1-pole breaker. Neutral will still carry the sum of currents, but, both hots total will be limited to the single breaker throw (e.g. 15A). Never place an MWBC on a duplex breaker! Note that this arrangement may create statutory code violations because it is effectively combining circuits that may not be permissible to combine, such as bathroom receptacles + kitchen receptacles.
