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Main breaker tripped but one circuit stayed on

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teknikfrog

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So this is weird. We had an ice storm yesterday and during a brownout the main breaker in my garage tripped. This garage is on its own meter.

One of the circuits ended up remaining on. I know this because it is the circuit that powers a surveillance camera and fiber optic feed from my house and I can see the footage before and after the brownout.

So something is seriously mis-wired in my panel right? What could even cause this? All other circuits in the garage--other outlets, garage opener, etc were off, but this one circuit remained on with the main breaker in the 'tripped' position.
 
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dcg9381

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If your main breaker turned off and a circuit in the sub-panel stayed on, yea something is really off.
If comfortable, pull the cover on that panel and post a picture. A few guys here are better than 99% of the master electricians that I've met.

Sure the camera isn't POE (power over ethernet)? Pretty normal that fiber goes to copper via a POE dongle somewhere. If it's POE and powered from a source at the house that would explain it.
 
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teknikfrog

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dcg9381 said:
If your main breaker turned off and a circuit in the sub-panel stayed on, yea something is really off.
If comfortable, pull the cover on that panel and post a picture. A few guys here are better than 99% of the master electricians that I've met.

Sure the camera isn't POE (power over ethernet)? Pretty normal that fiber goes to copper via a POE dongle somewhere. If it's POE and powered from a source at the house that would explain it.
Click to expand...
The camera IS poe but it gets its power from the garage.

The only way the house could be feeding power is via some very weird grounding ******* occurring via the armor on the buried fiber optic cable.. I do wonder if maybe that's the case. Should be easy to test for once this storm moves out.

I'll update the thread but it will be a couple days. I'll also snap a pick of my panel with the cover off.
 
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teknikfrog

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mike93lx said:
No Ups on the network switch?
Click to expand...

No UPS.

mike93lx said:
Its not possible for only one circuit to have power based on how a breaker panel is constructed. Maybe half the panel (one bus) stayed up and you only noticed this device.
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That sounds likely / probable. The panel only has like four circuits (the garage is recent construction and 90% of the panel is empty).

I did just confirm that the armor on the fiber cable ends about 8 inches before the fiber goes into the transceiver, so it seems unlikely to me that house was backfeeding power that way.
 
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mm08822

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Branch cb's tripping won't necessarily cause the main to trip and normally don't.
Even if the main trips, it doesn't mean branch cb's trip.
This is the purpose of cb coordination.

What was on the other branch cb's that were running and tripped at the time of brown out?
 
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reader2580

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mm08822 said:
Branch cb's tripping won't necessarily cause the main to trip and normally don't.
Even if the main trips, it doesn't mean branch cb's trip.
Click to expand...
In the vast majority of load centers if the main breaker trips all of the circuits in the load center lose power regardless if the branch circuit breakers are tripped, or not. The OP's load center still had power on one circuit when the main breaker was tripped and that is quite unusual.
 
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Innovate1

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Pull the cover of the garage panel and check if any of the circuits have power. Is there any chance some circuits are fed from the house - maybe it originally had a small feed from the house and later the garage meter was added? Strange things may exist sometimes. Pretty hard to imagine any way a weird ground through the fiber shield would do this.
 
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mm08822

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reader2580 said:
In the vast majority of load centers if the main breaker trips all of the circuits in the load center lose power regardless if the branch circuit breakers are tripped, or not. The OP's load center still had power on one circuit when the main breaker was tripped and that is quite unusual.
Click to expand...
Yeah. I mis-read the original post.
 
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dcg9381

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Innovate1 said:
Is there any chance some circuits are fed from the house - maybe it originally had a small feed from the house and later the garage meter was added? Strange things may exist sometimes.
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This is a good guess also. Turn off all the breakers at the house, see if you lose the camera.
 
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teknikfrog

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dcg9381 said:
This is a good guess also. Turn off all the breakers at the house, see if you lose the camera.
Click to expand...
Well I can't check the cameras if the house if off lol.

But again the garage is on its own meter. As in I get a standalone electrical bill for the garage by itself.
 
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teknikfrog

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justsam said:
Some cameras have a built in battery and really are battery cameras with an external power option. I know the Nest battery camera is this way. it is a typical USB 5VDC however, and not POE. Might your cameras have a small internal battery?
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No. I installed the cameras myself, they are uqibuiti. And even if for some reason they had a battery that still wouldn't explain how my fiber link and switch remained online, which are plugged into a garage outlet.

I'm 100% positive power on this one circuit remained on while the main breaker was in a tripped state.
 
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dcg9381

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teknikfrog said:
Well I can't check the cameras if the house if off lol.
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You have unfi cameras. Just turn on the indicator light (should be on by default). If it's a camera with IR and no indicator light, you can look at it through your phone's camera and it'll show the IR lighting provided by the camera.

None of my unifi cameras have batteries.
 
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wyliesdiesels

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teknikfrog said:
So this is weird. We had an ice storm yesterday and during a brownout the main breaker in my garage tripped. This garage is on its own meter.

One of the circuits ended up remaining on. I know this because it is the circuit that powers a surveillance camera and fiber optic feed from my house and I can see the footage before and after the brownout.

So something is seriously mis-wired in my panel right? What could even cause this? All other circuits in the garage--other outlets, garage opener, etc were off, but this one circuit remained on with the main breaker in the 'tripped' position.
Click to expand...
Are you sure the main breaker was truly off? did you meter the lugs on the main breaker?

how many branch breakers do you have in the panel? are they all on the same phase as the breaker that still had power?

the only way for something to be miswired would be for that one circuit to be connected before the main but unless someone spliced the service entrance, this wouldnt be possible

whats more likely is the main breaker wasnt fully opened and was still allowing power thru
 
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teknikfrog

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justsam said:
Has to be that one leg of the 240 breaker did not trip, and circuits on that leg remained alive.
Click to expand...
I'm 90% sure this is what happened.

Unfortunately I'm not sure I can replicate it, assuming it occurred in the tripped state and won't re-occur in the off state.

I'll get out and open the panel up at some point its just extremely cold out.
 
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wyliesdiesels

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dcg9381 said:
If your main breaker turned off and a circuit in the sub-panel stayed on, yea something is really off.
If comfortable, pull the cover on that panel and post a picture. A few guys here are better than 99% of the master electricians that I've met.

Sure the camera isn't POE (power over ethernet)? Pretty normal that fiber goes to copper via a POE dongle somewhere. If it's POE and powered from a source at the house that would explain it.
Click to expand...
you cant transmit power over fiber so how could that work?
 
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wyliesdiesels

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teknikfrog said:
The camera IS poe but it gets its power from the garage.

The only way the house could be feeding power is via some very weird grounding ******* occurring via the armor on the buried fiber optic cable.. I do wonder if maybe that's the case. Should be easy to test for once this storm moves out.

I'll update the thread but it will be a couple days. I'll also snap a pick of my panel with the cover off.
Click to expand...
not possible unless the armour isnt bonded and you have it connected to a receptacle.
 
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wyliesdiesels

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teknikfrog said:
No UPS.


That sounds likely / probable. The panel only has like four circuits (the garage is recent construction and 90% of the panel is empty).

I did just confirm that the armor on the fiber cable ends about 8 inches before the fiber goes into the transceiver, so it seems unlikely to me that house was backfeeding power that way.
Click to expand...
thats totally impossible unless you literally have the armor connected to a receptacle.... and it is touching a bare ungrounded conductor and it isnt bonded....
 
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sparky 1971

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1) main may have gone to the tripped position but one side didn't open because it's old and has never been exercised (they never are).

2) someone stuck a wire under the line side of the main (unlikely)

3) the garage may have had a circuit from the house, then had it's own service added to it and that circuit that should have been removed is still active.

4) Aliens.
 
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N_Jay

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teknikfrog said:
I'm 90% sure this is what happened.

Unfortunately I'm not sure I can replicate it, assuming it occurred in the tripped state and won't re-occur in the off state.

I'll get out and open the panel up at some point its just extremely cold out.
Click to expand...
Tripped 2-pole braker should open both legs.
Get it replaced,
Not "exercised" is no reason
 
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sparky 1971

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In addition to post #32. Since nobody even knows for sure that the main if defective, find out if the camera is actually fed from the garage because it's possible that the sky is not falling yet. Turn individual breakers off one at a time and see if the camera loses power, if you can kill the power that way, the main is probably shot and needs replaced. If it doesn't, repeat the process from the house. If it still has power, pull the cover off the garage panel to see if the line side of the main has been tapped. If that's still not the case, report back with pictures.
 
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dcg9381

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wyliesdiesels said:
you cant transmit power over fiber so how could that work?
Click to expand...
Same as others: I missed that the house to garage was fiber and any transition device (fiber to copper - likely POE) is assumed to be powered at the garage...

Seems like the OP should start flipping off individual garage breakers. That'd be my next step.
 
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