Troubleshooting tips and tricks...

[growler]

99.99% of the time when a branch circuit breaker is tripping it's doing its job. If I were troubleshooting this problem changing the breaker would be at the end of my list of things to try.

Me to but now that he knows that the microwave has probably tripped this breaker several times I do think I would change it out to be on the safe side ( and so I can charge them for it ).

People don't understand that breakers just don't normally go bad for no reason. Either there is poor connection at the buss or terminal causing heat or there is a short in the circuit that will cause heat.

To find a breaker that just says I quite, or factory defect is very rare.

 

[Besoeker]

Update-

Yes I did ohm out the conductors. That was the first thing I did after checking voltage.

Turns out it was the microwave that was tripping the breaker each time I tried to plug it in. I thought for sure I had also tried the lamp as well but I guess I was mistaken.

Yesterday When the maintenance guy showed me the issue my first thought was an issue with the micro but I got distracted because I thought I tried the lamp and had the same issue. Should've gone with my gut and double checked things better yesterday but was short on time.

First thing I did today was try the micro in 2 other circuits with the same results.

Live and learn...

In the words of Richmal Crompton, circumstances alter cases.

 

[Knuckle Dragger]

Tip: Wire a high-wattage incandescent bulb in-line at the breaker as a combo current-limiter (so the breaker can stay on) and status indicator (as you find the problem) using either a rubber socket or a receptacle with a lamp plugged into it.

Ground wire close to hot terminal of receptacle? What receptacles are you talking about? Kitchen, bath, or outdoors? As Hal suggests, it could be a mis-wired GFCI.

:thumbsup:

 

[gar]

190112-1927 EST

Here is the problem starting in post #1 that led readers astray.

Looking for people's favorite tricks and tips for troubleshooting a circuit where the breaker consistently trips.

It's a receptacle circuit that has 3 receps. As soon as you try to plug a load in (various loads were used) the prong tips arc'd to the Recep contacts and the breaker tripped. Voltage checked out good L-N & L-G. The original install was about 6 years ago. Everything is NMB and plastic boxes. Standard breakers.

Something is very inconsistent in what is said here and subsequent comments.

Voltage is good seems to imply that breaker could be turned on with no load on the circuit and that it did not trip with no load.

"As soon as you try to plug a load in (various loads were used) the prong tips arc'd to the Recep contacts and the breaker tripped."

"a load" implies only one load at a time was plugged in.

"various loads were used" and "a load" together implies that potentially different types and load power levels were singly tried.

I can not imagine someone hauling a microwave around as a test load at different sockets. A lamp is much easier. Also note microwave was not mentioned as the test load until the last posts. Arcing of plug contacts when plugged in implies the test load is a high current load.

When a problem is presented it needs clear definitions, and descriptions.

.

 

[rambojoe]

190112-1927 EST

. A lamp is much easier.

.

a plug tester works too... I think half the fun is guessing on the million random things it could be- when its not on your job!

 

[growler]

As soon as you try to plug a load in (various loads were used) the prong tips arc'd to the Recep contacts and the breaker tripped.

190112-1927 EST

Also note microwave was not mentioned as the test load until the last posts. Arcing of plug contacts when plugged in implies the test load is a high load current.

Normally even a microwave wouldn't put much of a load on a circuit just by plugging it in. A microwave wouldn't draw much current until the timer is set and it's turned on.

Something in the microwave must have been shorted. That arcing at the plug would not have been normal.

You are right and if they had plugged in a different load they would have determined it was a bad microwave in short order.

 

[ramsy]

Normally even a microwave wouldn't put much of a load on a circuit just by plugging it in. A microwave wouldn't draw much current until the timer is set and it's turned on.

Had this issue last week. 3 break-room Microwaves on 4 Ckts. Brand new Metal Clad 12/3 MWBC x 2 = 4 dedicated receptacles. Appliance cord & plugs / branch wiring passed Megger in Gig-Ohm range. 1 of 3 appliances started tripping new breakers whenever running without food or water in microwave. After a few days, 1 of 3 appliance end-of-life cycle advanced to tripping breakers whenever plugged in, without running at all.

Something in the microwave must have been shorted. That arcing at the plug would not have been normal.

Yes, DC voltage Megger tester can't detect it thru appliance cord & plug.

Can anyone recommend a hand-crank Megger tester that might generate AC rather than DC?

 

[K8MHZ]

Had this issue last week. 3 break-room Microwaves on 4 Ckts. Brand new Metal Clad 12/3 MWBC x 2 = 4 dedicated receptacles. Appliance cord & plugs / branch wiring passed Megger in Gig-Ohm range. 1 of 3 appliances started tripping new breakers whenever running without food or water in microwave. After a few days, 1 of 3 appliance end-of-life cycle advanced to tripping breakers whenever plugged in, without running at all.



Yes, DC voltage Megger tester can't detect it thru appliance cord & plug.

Can anyone recommend a hand-crank Megger tester that might generate AC rather than DC?

I have always been taught that running a microwave empty will ruin it.

When a microwave runs without anything inside, or if an item contains no water molecules, the microwaves in the machine will be redirected into the magnetron. When the magnetron begins to absorb as many microwaves as it produces, it can be damaged.



No Magnetron, No Microwaves



Since running your microwave without anything inside may damage the magnetron, it's advised to avoid this at all times. Without a magnetron, your microwave will no longer heat your food properly, if it heats it at all. When the magnetron breaks, you'll need to repair or replace your microwave.

 

[ramsy]

I have always been taught that running a microwave empty will ruin it.

Every break room should have that sign posted:

"Do Not Heat Small Items, without Extra Cup of Water."

"Small Items by Themselves will Destroy the Microwave"

"You are Recorded on Camera - New Appliances Deducted from Offenders Payroll"