Intermittent Circuit Failure

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Ok, I am gonna say this again slowly since no one seems to be listening:

FPE panel.

Evidently everytime the OP gets near it the problem clears for a while.

FOP ain't gonna find this one.

FPE panel.

FPE panels and breakers have a history of bad bus connections.

OP needs to carefully pull ALL the breakers, (pull the meter if there is no main, and/or if there is a main because you'll need to inspect the main to bus contacts as well.)

FPE panel.

Inspect each and every bus stab point, especially if they are the style attached to the bus with screws.

FPE panel.

Tighten any that are loose and/or replace the panel if any show signs of overheating or arcing.

FPE panel.

Do you customer a favor and suggest a replacement panel before the thing goes up in flames.

Hopefully this time my message registers. If not, here's a helpful visual aid courtesy of another forum:

attachment.php
 
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mxslick said:
Ok, I am gonna say this again slowly since no one seems to be listening:

FPE panel.

Evidently everytime the OP gets near it the problem clears for a while.

FOP ain't gonna find this one.

FPE panel.

FPE panels and breakers have a history of bad bus connections.

OP needs to carefully pull ALL the breakers, (pull the meter if there is no main, and/or if there is a main because you'll need to inspect the main to bus contacts as well.)

FPE panel.

Inspect each and every bus stab point, especially if they are the style attached to the bus with screws.

FPE panel.

Tighten any that are loose and/or replace the panel if any show signs of overheating or arcing.

FPE panel.

Do you customer a favor and suggest a replacement panel before the thing goes up in flames.

Hopefully this time my message registers. If not, here's a helpful visual aid courtesy of another forum:

attachment.php
Click to expand...

Nice panel:roll:
 
101005-0747 EST

I agree with mxslick that you should replace the panel.

However, voltage measurements should allow you to find the area of the problem.

Get a long extension cord and plug it into an outlet that is dead. Take the socket end to the main panel. Measure the voltage between each of the extension cord wires and ground. Use a meter that resolves 0.1 V.

Voltage between the EGC and ground should be 0.

Voltage from neutral to ground should be 0. If the voltage is much above 0, then there may be a neutral problem.

Voltage from hot to ground should be near 120 V.

With your circuit being dead you will not have anything near 120 V between neutral and hot at the dead receptacle. Depending upon on the above measurements decide whether to monitor hot or neutral relative to ground.

Assume hot is the problem. Then while the meter is still connected between hot and neutral wiggle the breaker to the problem circuit. Does the hot to ground voltage change? If it changes then it is clear there is a problem in the panel.

Next remove the panel cover, and assuming the circuit is still dead or a variation occurred in the voltage from the mechanical stimulation, then measure at the breaker output terminal the voltage to ground. Move the breaker around, wiggle it. If this is a solid 120 V, then the problem is in the circuit from the breaker to the load. But do a voltage drop measurement across the breaker with a large load on the breaker. If a 15 or 20 A breaker a 1500 W heater as a test load should be adequate.

A QO15 measures 0.15 V drop from bus to output terminal at 12 A after 15 to 30 seconds for the QO to warm up. This is a resistance of 0.01 ohms.

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mxslick said:
Ok, I am gonna say this again slowly since no one seems to be listening:

FPE panel.

Evidently everytime the OP gets near it the problem clears for a while.

FOP ain't gonna find this one.

FPE panel.

FPE panels and breakers have a history of bad bus connections.

OP needs to carefully pull ALL the breakers, (pull the meter if there is no main, and/or if there is a main because you'll need to inspect the main to bus contacts as well.)

FPE panel.

Inspect each and every bus stab point, especially if they are the style attached to the bus with screws.

FPE panel.

Tighten any that are loose and/or replace the panel if any show signs of overheating or arcing.

FPE panel.

Do you customer a favor and suggest a replacement panel before the thing goes up in flames.

Hopefully this time my message registers. If not, here's a helpful visual aid courtesy of another forum:

attachment.php
Click to expand...

Pretty impressive picture but it really tells us nothing as to why it failed or what failed first. I have seen a SQ D QO loadcenter with a hole burnt clear through the back of the box. Mid buss. Believe me it looked a whole heck of lot worse than this. Poor breaker connection is not unique to FPE. Get some age on them and most are POS.
 
ptonsparky said:
Pretty impressive picture but it really tells us nothing as to why it failed or what failed first. I have seen a SQ D QO loadcenter with a hole burnt clear through the back of the box. Mid buss. Believe me it looked a whole heck of lot worse than this. Poor breaker connection is not unique to FPE. Get some age on them and most are POS.
Click to expand...

The failure was at the main to bus connection. And if you look closely, it doesn't take a scientist to see what failed first.

Full story found HERE.

Post #4 has a full-size pic that shows the point of origin.
 
ptonsparky said:
Nope. It was a 100 amp w/ main 3R enclosure mounted on the side of a farm grain bin. Over the years it seems that I have replaced a lot of these due to burnt buss bars and loose breakers. This was the worst.
Click to expand...

So where was the main breaker in relation to the failure? Or was the failure at another high-amperage breaker?

Have never seen a bus simply burn out...unless it was FPE...:grin:
 
mxslick,

I hear what what you are saying....

My hang up with your plan is that there are 2 circuits that fail each time. This tells me that there is a shared natural. If it was a FPE breaker, would not just one circuit be loosing power? If it is a FPE breaker, why would 2 circuits be failing???

I have talked to the customer about replacing the panels (total of 3). He wants the failing circuits fix first.
 
mphillipps said:
mxslick,

I hear what what you are saying....

My hang up with your plan is that there are 2 circuits that fail each time. This tells me that there is a shared natural. If it was a FPE breaker, would not just one circuit be loosing power? If it is a FPE breaker, why would 2 circuits be failing???

I have talked to the customer about replacing the panels (total of 3). He wants the failing circuits fix first.
Click to expand...

Are the two circuits coming off of the same stab? (One on the left/right or top/bottom breaker locations.) See page 10 of THIS DOCUMENT (page 12 of the file) to see what I am talking about in regards to the bus construction.

Are you sure they're part of a mwbc? A lost neutral on a MWBC won't usually cause a loss of power, but an imbalance that will dim some loads and (potentially) burn out others.

Are you sure the two circuits aren't bootlegged onto one breaker? (A distinct possibility.)

And I would explain to the customer that with the history of those panels a failing set of circuits is a distinct warning that needs to be heeded, so panel replacement is a cheap alternative to a burned-down house.

ptonsparky said:
I think a 60 amp to a fan.
Click to expand...

Thank you for that update. That would make sense to me. I have seen such failures at high-amp loads before.
 
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mphillipps said:
I been called back to a house three time now because of a loss of power on one circuit.

Here is what I know:
  • Every time I leave the house the circuit is working.
  • The circuit originates at a FPE box (circa 1958).
  • The original 20 amp breaker was never tripped but the power was loss.
  • I've replaced the old breaker with a new breaker.
  • Within the panel, the breakers position was moved.
  • The circuit includes, kitchen, two bedrooms and two bathrooms.


I'm at the point to start looking for a loose neutral or a back-stabbed receptacle with a poor connection.

Are there any suggestions or thoughts on the breaker or the best way to hunt for a loose neutral?

Thanks
Mark
Click to expand...

mphillipps said:
mxslick,

I hear what what you are saying....

My hang up with your plan is that there are 2 circuits that fail each time. This tells me that there is a shared natural. If it was a FPE breaker, would not just one circuit be loosing power? If it is a FPE breaker, why would 2 circuits be failing???

I have talked to the customer about replacing the panels (total of 3). He wants the failing circuits fix first.
Click to expand...

Ok, so after 33 posts I'm not sure if I understand you correctly. "Loss of power" and "failing circuit" are pretty vague descriptions and it seems you're dealing with two circuits, not one?

- Are any breakers still tripping? If so, how many? If two, are they on the same or different legs? If two are they in the same panel?

- With a kitchen and two baths served from one circuit, the chances of an overload are way high (microwave, coffee maker, fridge and hair dryer(s) ). When is power being lost? Any patterns?

- As already asked, what's causing power to be restored? Just resetting a breaker? Who's doing that, you or the homeowner?

- How long has this been going on and did the homeowner do anything or have anything done electrically?

If this is two circuits tripping together, you need to widen the search to include things like chicago three ways that may have been on the same leg before but are now on opposite legs or other possible sources of a 240V dead short.
 
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