Troubleshooting time......

[c2500]

I own a rental condo. I am president of the owners association. The association is responsible for problems with wiring. My elderly tenant called me Friday, telling me her air did not work( and had not all week). I went over, and confirmed it. I checked breakers, and at the point of service, the 50 amp breaker was tripped. I reset it, it immediately tripped. The panel was very damp, and there was alot of corrosion below the suspect breaker (oxidized aluminum). I called out the EC who does work, and told them I was figuring the breaker was bad. (It definitely needed replacing with all the rust it had on it)

The tenant called me Friday afternoon saying everything was fine.

Tonight she called and said air was off again. I go over, the new "used" breaker is tripped. I turn the machine off at the thermostat, then tried to reset the breaker. The breaker will not reset. Finally on the 3rd try, it holds for a second then trips. I go turn the disconnect off. I go try to reset the breaker, it either trips or did not reset. The only odd thing is the breaker feels "sloppy". I am thinking short. The wire is UF. Coincidentally, a fence was added a few weeks ago. I think the post was dug in the area where the UF runs. The UF was installed in 1979. We have had it go bad in other areas. It was getting dark, and I had no tools or lighting with me.

I think the UF is bad between the point of service breaker and the disconnect.

Thoughts? Of course I have to be delicate with the EC, but used parts do annoy me.

c2500

 

[peter d]

Megger time!

 

[c2500]

I thought that might get said

c2500

 

[480sparky]

Megger time!

Recording ammeter time.

 

[peter d]

I thought that might get said

c2500

It's the only way to truly verify if the UF is compromised.

 

[GUNNING]

How bout look at the devices and look for the chard parts?

 

[Okie Sparky]

My first thought before if scrolled down & read the replies, was pull the breaker, pull the wires, meg the breaker, meg the wires. Why do the EC put in a used breaker? By state law we have to warranty our work for a year, so why be called back for a bad $15-$18 part? It also make for an unhappy customer on the hottest day of the year when it decides to get up and your back there replacing it for nothing. The fact that it's for nothing don't count right then.

 

[brantmacga]

try to reset with wires off the CB.

If it holds, check UF;

if its fine, the compressor may have gone out.

 

[Cow]

Megger would be my tool of choice.

 

[TOOL_5150]

try to reset with wires off the CB.

If it holds, check UF;

if its fine, the compressor may have gone out.

I like this method It breaks it down into 3 parts. Id also Meg the UF.

~Matt

 

[Pierre C Belarge]

I am curious. Your profile states you are a licensed electrician. How come you did not take care of this issue?



You mention that the UF has been compromised before. I sounds to me like that is a likely suspect. What about the corrosion on the circuit breaker, was the panel checked?

 

[LarryFine]

It's easy enough to do a preliminary check without a megger. Pull the wires off the panel breaker, throw the outside disconnect, and check each line conductor with a wiggy from a hot terminal. The one with the fault will show power.

If neither shows power, the fault is line-to-line, meaning you could connect power to one conductor, and the wiggy will show 240v power from the other conductor to the other phase.

 

[e57]

IMO "Bad Breakers" - DON'T TRIP!

The original breaker was doing exactly what it was meant to do - and so was the second one - used or not.

But I think you can have the necessary repairs done to the rusty panel, and replace the 'already-known-to-be-damaged' UF - and a perfect time to do it is when you finally realize that the compressor motor is failing - that's my diagnosis from the comfy chair..... Just start fresh.....

 

[c2500]

I am curious. Your profile states you are a licensed electrician. How come you did not take care of this issue?



You mention that the UF has been compromised before. I sounds to me like that is a likely suspect. What about the corrosion on the circuit breaker, was the panel checked?

Very simple Pierre......

The owners association will pay the bill. However, since I am president, it could be viewed as a conflict when I expected to get paid. Therefore, I let the normal EC do the work. (Not to mention I am in the middle of a remodel right now and do not have the time to work on it)


As for the corrosion, I ask them to check it. The problem is since I am not doing the work, I am at the mercy of the EC

c2500

 

[c2500]

Well I just spoke with the EC. I ask if he would megger the line. He said they don't own that expensive testing device. (I don't have one either, but then again I don't do electrical day in and out). He tapped danced around the used breaker and said his guy would be outh there later this morning.

It is kinda fun not being the one in the crosshairs for a change

c2500

 

[ohm]

Well I just spoke with the EC. I ask if he would megger the line. He said they don't own that expensive testing device. (I don't have one either, but then again I don't do electrical day in and out). He tapped danced around the used breaker and said his guy would be outh there later this morning.

It is kinda fun not being the one in the crosshairs for a change

c2500

I'll bet he's thinking "I don't like working for someone who knows what I'm doing".

 

[growler]

I don't know why everyone thinks you need a megger for this job. A megger is used to find insulation leakage. If you have enough of a short to trip a 50 amp breaker then even an ohm meter should confirm it's shorted.

If nothing else put and amp meter on it and turn on the breaker with the A/C united disconnected, it shouldn't draw any current with no load.

All a megger would tell you is that you have a short and I think you already know that. What's needed is to locate and repair or replace.

I don't use used parts but I doubt if it made any difference in this case. Once the problem is repaired I would have them replace with a new breaker of the correct size. Not many A/C units use a 50 amp breaker to the condensor unit ( they should size to name plate ).

 

[charlietuna]

Something cause the first breaker to trip --- then you placed the thermostat in the off position which isolates the compressor from calling. And it still tripped -- only thing in the circuit would be the control transformer and that whould most likely open up!! I would point a finger at the fence installer and confirm it by disconnecting the breaker's wires and meggaring them. Then replace the breaker with new prior to completing the job..

 

[Pierre C Belarge]

I think the post was dug in the area where the UF runs. The UF was installed in 1979. We have had it go bad in other areas. It was getting dark, and I had no tools or lighting with me.

I think the UF is bad between the point of service breaker and the disconnect.

These are the first areas I would check at this point.

c2500

Very simple Pierre......

The owners association will pay the bill. However, since I am president, it could be viewed as a conflict when I expected to get paid. Therefore, I let the normal EC do the work. (Not to mention I am in the middle of a remodel right now and do not have the time to work on it)

I understand now, it makes sense.

As for the corrosion, I ask them to check it. The problem is since I am not doing the work, I am at the mercy of the EC

c2500

Something cause the first breaker to trip --- then you placed the thermostat in the off position which isolates the compressor from calling. And it still tripped -- only thing in the circuit would be the control transformer and that whould most likely open up!! I would point a finger at the fence installer and confirm it by disconnecting the breaker's wires and meggaring them. Then replace the breaker with new prior to completing the job..

Read the above.

 

[220/221]

If the AC breaker trips, wouldn't you simply disconnect the circuit at the disco (or at the unit if no disco) and try to reset?

That narrows it down to the feed or the unit.

If the circuit is good, the next step would be to disconnect the compressor or motor(s) and try again. If it's a condensor or evaporator motor and it's mine, I will replace it myself. If it's a customers unit, I tell them to call an AC guy.