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It is so easy to measure drop across the breaker that there's no excuse not to do it every year. I wanted to see how bad it would get if it were left alone.

The stab contact itself maintained a low resistance that's a negligible part of the total. Most of the heat is generated inside the breaker. It would at worst precipitate a thermal trip. Resetting it would re-seat the circuit interrupting contacts.

I believe that, in day-to-day use, the panel is as safe as ever. The risk is when a tech removes breakers. If both breakers on a stab are pulled, the second one may take the clip* with it, and it could fall onto the bus and arc. I glued them in place, but my private notes include a warning to hold it down with a nonconductive tool. I would have loved to spot-weld them but I don't have the means, and anyway, the bus would be live. Been there done that not gonna do it again. =8)

* A plain brass strip folded over the corrugation to make it resemble GE's new profile.

Thanks for the encouragement.

Dave
Dave,

Gluing them in place?

A stern reminder is in order that the things we do today will outlive us. Whether people have hobbies in tinkering in areas like this or not, it does not give people the excuse to perform modifications or make installations that do not abide by the current Codes, no matter the trade or how trivial the work, even if you are the owner.

In a situation like this, even if you are comfortable taking this risk on in your life, and even the chance of potentially exposing your community to a hazard via overheated service entrance conductors, what would happen if you were to suffer a death via car accident unexpectedly? - you would not be around to handle these mitigated risks you have taken, and now you have exposed a stranger to a potentially life-threatening situation.

Let your hobby coincide with safe installations and practices. Leave this world a little better than you found it.
 

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A little more than a year, however the message is still crucial to anyone coming across this thread.

A person like Dave should seek employment with a testing laboratory in a controlled environment rather than expose real people to dangerous conditions.
 

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Discussion Starter · #44 ·
I'm "following" this thread but I did not get notified about the new posts.
I will replace the panel in the next few years. Besides tampering, it's full and I want to add a couple circuits. (An outdoor 120V receptacle, an individual circuit for the spot water heater, and if I get another car it might be electric needing a charger.) Probably a GE TM3220 since I want to reuse the breakers.
 

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Since you've modernized the breakers, the real threat here is the core problem with Rule-of-Six panels. That being the breakers sum up to well over service rating, so nothing prevents you from overloading them.

You might as well just replace the panel with a meter-main at that point. Or just install a main-breaker panel before this panel.

Some panels provide a main breaker and 8 breaker spaces, and then "thru lugs" intended to go onward to another full-size panel such as this one. That will get you 8 more spaces and eliminate the safety issue with Rule-of-Six. Now you don't have to rewire any circuits in this panel.
 

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Discussion Starter · #46 · (Edited)
Glad to hear from you Mr. Harper.

I wouldn't dream of overloading the service. The existing breakers add up to 240A or 120% of service which complies. My problem is I'm out of slots and no tandems available. (GE Type TR was discontinued 50 years ago.)

The old panel is flush-mount in the common wall between house and garage, with meter pan flush in front of the house a couple feet away, with mast straight up through the roof. There's no room for a meter-main, we are right next to the garage door.

Feed-through main breaker panel sounds... really good! (Sometimes called a trailer panel; not a ranch panel, that's a meter-main-distribution combo.) I see models available from several major mfrs. Looks like the biggest panel with flow through is 8 spaces. Eaton BR816B200RF is 13-1/4" x 24", Siemens is taller. I figure 4/0 AL SEU from the pan to the new panel (same as current construction), and SER from there to the old one. That would support 16 single-pole circuits using tandems. Big safety feature is we can dead everything by throwing main. I'll still lose house power during install but way less than a full swap. Thanks!

Oh-oh, I'll have to unbond neutral and ground at the old panel. Was it just take out a screw back in 1960? GE TRX2820 in case you have an ancient datasheet. I'd look but right now I'm in a cast recovering from surgery.
 

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Discussion Starter · #47 ·
I measured and looked around for a while in the garage, and I decided the feed-through panel is just too awkward to install, I don't really have room to do it clean. After obsessing for an entire day, I think I've come up with a sequence that I can handle, for cutover to a panel swap. I'll do it in spring or fall when we don't need heating or cooling.

The new panel will be a GE TM3220CCU, which has 32 positions, and up to 40 circuits because some rows support THQP. I wanted TM3220C64 (64 circuits) but the box is bigger and it won't fit.

SCRIPT:
Cut out drywall around old panel.
Provision new panel with #10/12/14 cable clamps. (Not SE/6/8.)
Temporarily surface-mount new panel next to old.
Remove dead fronts.
De-energize/disconnect/unclamp nonessential branches and move their breakers.
Connect #6 temp feeder wires to new panel. Hots and neutral.
Turn off 50A Sub-Main B breaker.
Disconnect old Sub-Main B feeder and connect temp feeder.
One by one, disconnect and remove essential cable, move breaker, and extend from old panel to new panel, entering through clamps.
Cover up remaining unused stabs in the new panel.
Turn on Sub-Main B breaker.
Turn off and remove Sub-Main A breaker.
At this point we have essential branches via new panel - 50A max - and range and dryer via old panel.
We can go this way for days if necessary.
ON CUTOVER DAY:
Turn off range, dryer, and Sub-Main B breakers.
Pull meter.
Remove from old panel: SE cable, temp feeder, range and dryer breakers and cables, and Sub-Main B breaker.
Remove empty old panel.
Mount new box.
Insert/clamp/land SE cable.
Inspect, reinstall meter, energize.
Install range and dryer breakers.
Insert/clamp/land range and dryer cables.
Turn on range and dryer breakers.
AFTER CUTOVER:
We can go this way for days if necessary.
One by one, de-energize a branch, remove extension, insert/clamp/land.
Install new drywall.

Have I missed anything?
 

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On panel height, forget about using double-stuff breakers as a substitute for adequate spaces. So many circuits need GFCI/AFCI now, and spaces are cheap. If you need more breakers in a given height, look at Square D "QO" or Eaton "CH" which put 40 breakers in the physical spaces everyone else puts 30.

So you're saying install a new panel temporarily next to the original panel site, and move critical circuits over there?

Sure, then leave the panel there permanently as a generator subpanel LOL. You could use more spaces anyway... finishing the upgrade with 26/30 spaces used is far from wise. Spaces are cheap and as you say, you have loads of headroom and you're out of spaces. "out of spaces" is easily avoided with expenditure of a very small amount of money.

At that point, shoot, just feed the new subpanel off the old main, and stop right there, you're done. I seriously doubt the two 8-space "mini-panels" inside the old main really need 50A each, so tee them off of one 60A breaker and use the other to feed the new sub.

"Wow, we're already done".



When you move the cables from the old panel to the new 2nd panel, those splices need to happen inside an approved enclosure with enough space in it. Its cover must remain accessible without tools, cannot be buried under building finish materials. Frankly I never understood the appeal of finishing utility spaces. It just makes utilities more messy and expensive to maintain.

I don't see how you plan to transition between a flush mount old (and new???) panel and a surface-mount subpanel. That doesn't make any sense to me. The few times I've tried, it involved supreme jackass code violations, like leaving the deadfront intentionally off the panel (which on a non-bolt-on panel will make the breakers fall out, just to add even further to the fail). So I would flush-mount the second new panel, and hollow out the studs for passage ways for a conduit run between them. If the conduit is over 24" you face circuit limits based on thermal derate (4 circuits per pipe for 10-28A).



To isolate ground in an old panel, you just need to make sure neutral is on a bar isolated from equipment chassis. Grounds are grounded directly to chassis, and you can retrofit accessory ground bars.


You need to do it right, though. Otherwise the power company is not going to cooperate on the meter pull, as they will want to see permits pulled for the relevant work. You can't just remove a meter as it has an anti-tamper seal on it. If the power company is unaware of a meter pull, they'll find the broken seal and then go after you for energy theft.
 

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Discussion Starter · #49 · (Edited)
Thanks! A lot to think about.

I wouldn't dream of leaving off the dead front! That was Temporary Wiring only. Just during the run up to cutover and the cooldown afterward. I planned to end up with a TM3220 in the exact same spot, mounted and wired the same way, as the old TRX2820.

I wasn't going to use any skinnies myself, just the next owner after I'm dead. If I spread way out, plus add an electric car charger to future-proof, I wind up filling 32 spaces. The next guy can eke out eight more poles if he wants a shop.

On the one hand I'm trying to reuse all those breakers I bought a few years ago, and on the other I'm working by what's available, and on the third I'm going on what fits the space. The only models that do all three are TM3220CCU and TM4020CCU. The latter gives me 40 full-size spaces but no skinnies so it's the same circuit max, plus it's expensive and hard to get right now. ($300+shipping minimum vs $160 and most of the places want like $1000 or "sign up to see the price" which never ends well.) At that price it's a wash between buying all new breakers and buying the expensive panel that takes the current ones. By the way, one of my leads is a $300 TM3220CCUAF9K kit which comes with five 15A CAFCI breakers. I can use four of them and upgrade my safety.

I was only going to surface-mount temporarily, then sink it into the old box's hole during cutover. I was trying to avoid permanent splices. And messing with the meter pan and running new SEU. Am I flinching at a shadow? How hard is fishing 4/0 SEU?

By the way, the reason I ran aground with the trailer panel idea is that the only ones available are outdoor i.e. surface mount, plus they're huge - as bulky as the TM3220 while still only adding eight spaces. A trailer panel plus my old panel is no better than just a TM3220 - they each total 32 full-size positions.

<Wow, we're already done>
But it sounds like you propose to sub the new panel off the old. If I understand you right, we've failed a prime objective: getting a main-breaker service instead of a rule-of-six service. If the old panel stays in the picture, the flow has to be meter to new panel to old panel. And as you say, the old panel has to de-bond neutral and ground. There's no ground bar today. I doubt I can get one.

If I de-bond the old panel, then I suppose I could flush-mount the new panel next to it, run new SEU from meter to the new panel... what's the best way for a novice to splice it?
...And feed say 100A to the old panel, and migrate the old rule-of-six main-bus loads to the new panel. I'll try to determine how bad a new SEU run would be. At best I suppose it's just pulling down a bigger hunk of drywall and boring a couple studs. It depends on what's going on at the meter. If they clamped or stapled in an inaccessible spot it's a deal breaker, I'm not playing in a live socket! I'll ask the POCO about cutting the drop. (They were fine with a DIY panel swap, just pull a permit at City Hall. City Hall was very friendly, inspector said call me anytime ask me anything. They've worked with me before.)
 

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Discussion Starter · #50 · (Edited)
I forgot to say. This house is nothing special. It's a 1960 tract house, in a tract house neighborhood. 1600 sq ft including finished basement, electrically heated, 3BR 2BA, 1/4-acre lot. There's not going to be a servants' cottage or carriage house. There's not going to be an addition in my lifetime, or likely ever. Due to shading, PV is not a contender. My old panel is the biggest I've seen around here.

My neutral bar does have a bonding screw, see photo, at the center of the vignette. (It has 48 small screws, 5 medium lugs - one with double-stuffed neutral, oops - and one huge lug for the SE neutral.) There is no separate ground bar. There's enough space to add one, but there are no mounting holes. I will ask the AHJ if drilling and tapping holes (10-32) and mounting a modern ground bar is okay. (GE TGK24.) If they say no, this rules out keeping the old panel.

The 100A breaker I mentioned last night (to feed the old panel from the new) is a THQL21100. It's about $50, not bad.
The label does not say how small a wire I can put in the main lugs. There's 4/0 in right now. THQL21100 max is 1/0. Is that likely to pass inspection? What's the proper torque on those old main lugs?

Either way, I'm looking forward to being free of rule-of-six, but I'm in no hurry except with respect to product availability.

Your reminder in other threads that most/all new branch circuits are required to be AFCI and/or GFCI makes me understand why you've begun dismissing tandem/skinny breakers. I didn't get it before. I will stop being satisfied with 32 positions. In GE land, that means subbing the old panel or hunting down a TM4020, oh joy. Or dropping GE and pricing out other brand panels plus their breakers, more joy. :)


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