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Discussion Starter · #1 ·
I had a short, caused by my being galactically stupid stupid stupid, well at least I am still alive.

I thought I had the panel turned off. Well I did. I then turned it back on for a second to open the garage door, then a phone call distracted me, and I forgot to turn it back off, and I proceeded to do stuff as if power was off!!!

I was in the middle of doing some major reorganization and rewiring in this 200A Siemens subpanel. I have added a new 3/4" EMT conduit connection at the bottom of this panel and I was pulling some new THHN conductors from a junction box into the panel. Some bare copper ground conductors got in the way, and I wasn't paying attention as I pulled the new conductors in, they shifted the positions of the bare ground copper conductors and they made contact with the metal bus at the bottom. A loud pop and everything on this side of the house connected to this subpanel went off.



Here you can see a close up where the bare ground conductors (two of them made contact).



Here you can see the lowest part of the bus where there is a metal burnt mark.



Yes I know the wires were all messy and should be neatly tucked away, but they were this way because I untangled them to replace them.

It was scary as it was pretty loud and some sparks.

So now the lower two fins of the bus, they are now damaged? Is it damaged serious enough to cause problems if I ever add more breakers to connect to them? I assume you can't replace a section of the bus you must replace the whole thing?
 

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I wouldn't put a breaker on the lower bus, left side. Right side should be OK.

Second row from the bottom, should also be OK. I would shut the panel down again, verify it dead, and then file slightly on the 2nd buss from the bottom. ( just to remove the burr )

Steve
 

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You just descovered the principles of welding. Easy to forget. This is why youalways assume everything is hot even if you "know" it isn't.
Iwould try to avoid using the bottom left finger. The top one is OK.
 

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Discussion Starter · #4 ·
every time I get into trouble it's due to some phone call distracting me. Last time it was a pot I had no the stove that I was heating then a phone call and I soon forgot about the pot then went outside to the backyard to mow the lawn for an hour until the smoke alarm went off in the kitchen.
 

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Discussion Starter · #5 ·
I do not anticipate to ever need to expand all the way to use up all 40 slots, but never say never. I am on slot 25 now and I have a few unused one above that I have disconnected due to switch some appliances to gas.

But in the event I do need that slot, what would be the remedy? Replace the entire bus? Replace the panel? Or leave that and switch a few slots to use the skinny tandem breakers?
 

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Many years ago I was working in a computer room on an Army post. This was the kind that had a raised floor that the power and other wires were run under. I was pushing this section of liquidtite from one side of the room toward the PDU (essentially a cabinet with a step-down transformer and three QO panels in it). What I hadn't noted was that the conduit was riding on top of other conduits and got into the PDU and touched the terminals on the transformer. The breaker on the transformer tripped (500A three phase thing) and I noted that all the emergency stop lights were also out. These were fed by a separate breaker/transformer on the primary side of the PDU.

A minute later the computer guys showed up to ask what had gone on and if I was OK. I told them I was fine but someone needed to go retrieve the master key because the breaker on the substation had tripped and we needed to reset that. I was lucky that I was handling the plastic part of the conduit. The metal fitting at the end of the conduit had the nut welded to the threads.

The next day a sign appeared on the door saying "Ron's Welding Service -- Arc Welding a specialty."
 

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every time I get into trouble it's due to some phone call distracting me. Last time it was a pot I had no the stove that I was heating then a phone call and I soon forgot about the pot then went outside to the backyard to mow the lawn for an hour until the smoke alarm went off in the kitchen.
Had a similar experience about 30 years ago. Mine was eggs in one of those really cheap aluminum pans. Put the eggs on to boil and went out to my shop where I proceeded to totally forget about the eggs. An hour or so later went back in and the only thing left aside from the foul aluminum/sulfur smell was the very top ring of the pan still attached to it's handle and a couple scraps of eggshell.
 

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Yes I know the wires were all messy and should be neatly tucked away,
Messy wires are not bad. What is bad is when your wires are too short to give you freedom to move breakers around,

Those ground wires have lost cross-section and thus are not safe. It looks like those wires are taking the scenic route though, so add a $6 accessory ground bar to this panel, and terminate them there.

You just descovered the principles of welding. Easy to forget. This is why youalways assume everything is hot even if you "know" it isn't.
Iwould try to avoid using the bottom left finger. The top one is OK.
I agree, the bottom left finger is ruined.


But in the event I do need that slot, what would be the remedy? Replace the entire bus? Replace the panel?
You don't need that slot. It is dead. You do not have it, so needing it is irrelevant.

If you are hellbound and determined to get it back, then A) get accessory ground bars for this panel and move all grounds to them. B) have your electrician change your meter pan to a meter-main, so you can do this next part safely, because handling unfused service wires live is out of the question.

Then C) Look closely at the panel bus assembly for any labeling that says "use box number so-and-so". Also get the model off the label and look it up in the Siemens catalog and look for the "box number" that panel uses.

Now D) get a new Siemens catalog and find all the panels that use that same box number. Buy the best. (Generally that means most breaker spaces, and since your main breaker is now out at the meter-main, this can be a main-lug panel. If you are a copper zealot, some Siemens panels have copper bars.)

E) you now have 2 panels right next to each other with the same box size. Look very carefully at the existing bus assembly, which is everything in the panel that is not the empty rectangular box, wires, or the accessory ground bars. It should come out with 3 screws and no more, all of which go into the outer rectangular box. There will be no disassembly of the bus assembly itself!!! However one of the screws might lurk under the main breaker. Got that reconnoitered? Okay.

F) go down each breaker and double-check that each wire is torqued on gud-n-tight. Really thus should be set with a torque screwdriver. Shut off the meter main and grab a flashlight. Remove all breakers and let then dangle by their wires, and remove all neutrals from the neutral bar, and the main feeder (formerly service entrance) wires onto the main breaker (which are de-energized because you shut off the meter-main). Do not do this live. Really.

G) pop off the 3 screws and drop out the entire bus assembly.

H) pop the new bus assembly on, hook up main feeder wires, neutrals, breakers, done. Torque wrench mandatory on large feeder wires, and on all wires really.

It's a 20 minute swap, but it's ALL planning and prep.
 

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Discussion Starter · #10 · (Edited)
Messy wires are not bad. What is bad is when your wires are too short to give you freedom to move breakers around,

Those ground wires have lost cross-section and thus are not safe. It looks like those wires are taking the scenic route though, so add a $6 accessory ground bar to this panel, and terminate them there.
Those ground wires were all in the process of getting replaced. That's why they were all untangled. They are no more.

If you are hellbound and determined to get it back, then A) get accessory ground bars for this panel and move all grounds to them. B) have your electrician change your meter pan to a meter-main, so you can do this next part safely, because handling unfused service wires live is out of the question.
I can get this entire panel de-energized including the feeder wires because this is a sub-panel. The main panel is on the other side of this wall, and the feeder wires are connected to the main lugs of the main panel. I can turn the whole house breakers off in the main panel to completely de-energize this panel.

I guess I am going to hold off since I still have 16 empty slots left in this panel and 3 in the main panel.

But now I am thinking may be my stupid accident actually might have caused more damages that meets the eyes. I will describe it in my next post.
 

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They sell little timers that you can put on a keychain. I used to train myself to set it for 15 min or so when I was in the middle of something important in the hospital & had to get back to it. I kept the little timer in my pocket.
Jewellery Body jewelry Font Chain Clock
 

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Good news about already being a subpanel! It's downhill from there!

If you are thinking of a bus assembly swap, the risk with "holding off" is that periodically, they change the panel and box sizes. Once they do, you will no longer be able to get a panels whose guts swap into this one.
 

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Discussion Starter · #13 ·
So once the breakers were tripped and I did a hard off and on, everything came back normally, seemingly for a while.

Then all of a sudden, some lights went off. I checked around and it appears I lost half my circuits. Looking at the panel, every other circuits from top to bottom (1, 5, 9, 13...) dead and the other ones (3, 7, 11...) are OK. Looks like I lost one leg of the service?

I waited about 10-15 seconds, everything came back on by itself.

A few hours later, I pressed the push button to operate the garage door opener, and as soon as I pushed it, the house went dark again, and it seems the same circuits are off.

As I mentioned in the original post, this is a subpanel, with the feeder wires coming from the main panel on the other side of this wall. There are no breakers for this sub in the main, the feeder wires are connected to the bottom lugs of the main panel.

So I went to the main panel, and I noticed half the circuits on the main panel are off as well. If I then turn the whole house breakers off and on, it will turn everything back on again.

Since then this has happened twice again. Each time, I was able to restore everything by turning the whole house breakers off and on. I haven't figured out if there is a consistent trigger to this, and it seems very intermitent. The only thing I noticed pushing the garage door button triggered it twice.

Is it possible that this short accident in this sub, actually caused some damage to something to have caused this? Or something is wrong with my service that seems to be coincident with my shorting the panel bus?

Any idea how I would trouble shoot this new issue?
 

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Interesting. Usually the dead half circuits don't die altogether, they kinda "wheeze". Because the dead phase is connected to the live phase via the 240V loads.

Maybe that's what's causing your intermittent behavior.

To find the problem definitively, shut off every 240V load in the house. Then see if all those wires go stone dead and stay there.

If so, you lost a phase somewhere - sounds like it can only be at the meter or weatherhead or utility pole top. All 3 are the power company's responsibility, however you are responsible for maintenance of the meter pan. It's possible your dead short over-strained a connection that was going to fail anyway in March.
 

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Discussion Starter · #15 ·
Interesting. Usually the dead half circuits don't die altogether, they kinda "wheeze". Because the dead phase is connected to the live phase via the 240V loads.

Maybe that's what's causing your intermittent behavior.

To find the problem definitively, shut off every 240V load in the house. Then see if all those wires go stone dead and stay there.

If so, you lost a phase somewhere - sounds like it can only be at the meter or weatherhead or utility pole top. All 3 are the power company's responsibility, however you are responsible for maintenance of the meter pan. It's possible your dead short over-strained a connection that was going to fail anyway in March.
Thank you.

OK I am not quite following the "Then see if all those wires go stone dead and stay there." I don't have that many 240V circuits, since I use gas, so range, dryer, water heater etc...are on gas. The only 240v loads are the pool pump, and the two central AC systems. So I turn off the breakers for those in this subpanel as well as the main panel correct? Then what is the next step? Wait for the problem to happen again, and see if I am still able to restore power to everything by turning the main breakers off and on?

Is this something I should contact the POCO to check? I don't know if they are able to detect any issue with the overhead power lines, I do have a smart meter. However, due to the DIY work I am doing on the panel I am concerned if they want to see this subpanel which is right now a work in progress.
 

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Back in my telco days, I was installing a phone line to a new building. Whenever possible, we ran the f-drop from the pole to the building following the power line. This kept things neat and also allowed us to ground the network interface device to the electrical ground (a lot easier than driving a 6-foot copper ground rod with a 5-pound sledge hammer by hand).

Unbeknownst to me, the moron that installed the electrical line from the pole did not insulate the connections properly at the power mast of the building. As I was securing hook for the f-drop to the power mast, I jostled the powerline. Suddenly there was a bright flash and POW!!!. Fracking electrical line shorted right in front of my face.

Now the really scary part.

At the same time the line shorted, I felt something hit the lens of my Ray-Ban sunglasses which I always wore outdoors. When I took them off to check them I found a small piece of metal had melted into the glass lens. There is no doubt that had I not been wearing those sunglasses, I may very well have suffered a server eye injury or even blindness in that eye.

The owner of the building was livid with the electrician who did the install when I explained what happened.
 

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The next time you lose power, measure with a volt meter at the main breaker before you touch anything else. Measure from line to load on each pole. If it's tripped you will read 120V, if it's still closed you should read 0V.

This will tell you if the main breaker has gone bad. Sometimes they trip internally but the handle doesn't move.
 

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Discussion Starter · #18 ·
The next time you lose power, measure with a volt meter at the main breaker before you touch anything else. Measure from line to load on each pole. If it's tripped you will read 120V, if it's still closed you should read 0V.

This will tell you if the main breaker has gone bad. Sometimes they trip internally but the handle doesn't move.
Thank you!

OK just to make sure. Do you mean the breaker for the subpanel where the short happened or the whole house breaker in the main panel?

This is the breaker for the newer subpanel at the top. The one that tripped after the short and I had to push real hard to OFF back to ON.



This is the main panel on the other side of the wall, It has 4 breakers at the top which are the main breakers for the entire house (including main plus two subs).



Since the lost on half the circuits happen on the main panel as well, I am assuming you mean to test it across the main panel breakers line and load. So to make sure I understand fully, this means with my volt meter, when this problem occurs again, I will measure the voltage difference between the RED and YELLOW areas in the following pictures.



If the breakers have tripped are functioning property, I should get 0V. Then the problem is elsewhere. If I get 120V, then there is a problem with the breakers and a replacement is needed.

If the problem is elsewhere, then I will do what seharper suggested, to turn off all 240V loads in main and subs, to see if the half energized circuits are now dead or still alive?

Or should I do the line/load across breakers voltage measurements with all the 240V circuits turned off to ensure there isn't anything crossing over?
 

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Go straight to the main breaker in the main panel. Don't touch anything else. Measure where you have indicated. 120V indicates the breaker is open regardless of handle position. 0V indicates the breaker is still closed and the problem might be in the meter base, or more likely the utility connections.

So far I'm guessing the main breaker as the problem goes away on reset.
 
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