Trailer park AC question

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sparky_magoo

sparky_magoo

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Reno
I am dispatched to a service call at a mobile home on Monday (I hate mobile homes). The problem is, when the HO turns on the AC, breakers trip in six other mobile homes. In the offending mobile home, no breakers trip.

How can this be? Before I go out there, I would love some input from you people. I am a full time serviceman and am a much better service tech. because of this forum.

Before going out there, the only thing I can think of is an open nuetral. Any input from the brain trust would be greatly appreciated.
 
Here's a pretty good guess....

The inrush current of that AC starting up temporarily draws down the voltage on a failing or sorely undersized utility (or possibly park owned) transformer.

The reduced voltage causes higher current draws for all circuits across the board, for all folks on that transformer.

Any trailers that have one or several circuits heavily loaded (close to tripping anyhow) will now have an even higher realized amp draw (due to that new, lower voltage), and will trip.

I'd try to take some AC not running, AC running, and AC starting voltage readings here and there and see what you come up with. If these people only have issues when this person's AC actually starts, you might try adding a hard start kit for corrective action.
 
I agree a hard start cap might help but this sounds like a undersized service for all of the trailers.Is it tripping mains or just single breakers ? Is this a central air or window unit on 120.If its a 120 i would check for neutrals at service.
 
mdshunk said:
Here's a pretty good guess....

The inrush current of that AC starting up temporarily draws down the voltage on a failing or sorely undersized utility (or possibly park owned) transformer.
Click to expand...

Thats as good as anything I can come up with but it IMO still seems unlikely.

The large majority of loads in the other trailers will draw less current with reduced voltage.

Even motor loads do not always use more current when the voltage drops, sometimes they just produce less work.

It is an odd one please let us know what you find.
 
sparky_magoo said:
I am dispatched to a service call at a mobile home on Monday (I hate mobile homes).
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Sparky, it sounds like you have been down this road before. The only advice I can give is don't try and come up with any pre-conceived idea of what the problem could be. I have found trailor park wireing at times to be most unprofessional ( rigged ).

I like to start out by confirming the symptoms. Did this A/C unit ever work or was it installed by a maint. man friday. What is the connectin with the other six mobile homes. Are they all fed from the same meter bank. It wouldn't surprise me if they had the A/c hooked to someone else's service, they may even have one of the hot legs hooked up to neutral.

The only thing I would expect to find is a real mess.
 
Thanks for the ideas. I don't know if the other trailers are tripping main or branch breakers. My dispatcher doesn't know enough to ask detailed questions. I have asked many times to decline work in trailers. I can track down problems in large commercial / industrial situations, but trailers seem to regularly kick my butt.

I have an Amprobe ACDC-3000 clamp meter which can measure the AC units in-rush current. It also has a logging function which can measure hi, low & average voltage levels.

The trailer has been in place about a year. It took all summer long for the tennants to figure out what is going on. Thats all the info. I have.
 
once i was called for an a/c unit not working in a mobile home park, the breaker was tripped so i reset checked the unit and found no problem , called back two days later, breaker was tripped again, checked it all out again and could find nothing so i replaced the breaker. two days later called back again, the breaker was tripped. so checking everything again this time i found an extension cord hidden extremely well behind the underpending i thought hmmmmm. so i start pulling on it, it goes under the trailer it keeps going all the way down to the end so i keep pulling an it is nicely buried into the expansion joint of the concrete feeding the trailer next door. lol the people saw me coming to the front and disconnected it and threw it out the back door claiming they didnt know anything about it. i informed the owner and the park manager, of course the were already under eviction notice.
 
sparky_magoo said:
Thanks for the ideas. I don't know if the other trailers are tripping main or branch breakers. My dispatcher doesn't know enough to ask detailed questions. I have asked many times to decline work in trailers. I can track down problems in large commercial / industrial situations, but trailers seem to regularly kick my butt.

I have an Amprobe ACDC-3000 clamp meter which can measure the AC units in-rush current. It also has a logging function which can measure hi, low & average voltage levels.

The trailer has been in place about a year. It took all summer long for the tennants to figure out what is going on. Thats all the info. I have.
Click to expand...

Actually i love calls like this.Something to keep your mind going.
 
Just go in with open mind.Ask the key questions like did it ever work,was it worked on just before this new problem, anything else been added.Often the description that you were given does not match real problem.After it goes thru 3 or 4 people it changes.Might not even be a trailer by time you get there.
 
I went to the site today. I found an old Bulldog switchgear with what looks like Pushmatic Breakers. Each feeder has a 60 amp 2 pole breaker. Each pole of the 60 A brkr. serves two trailers. In other words, a 60 amp 2 pole Pushmatic breaker serves 4 mobile homes. I told the park owner she needs to upgrade the service. She also must provide a 50 amp service to each mobile home.

I refused to just install a new Pushmatic 60 A 2 P brkr. to temporarily alliveate the problem. I referred the issue to the company owner, who may prepare a bid to upgrade the park to current standards.
 
Thanks for that update. It's good for the education of us all when we know what came of these puzzlers. It seems like you have a situation where you have "undersized everything".
 
sparky_magoo said:
I am dispatched to a service call at a mobile home on Monday (I hate mobile homes). The problem is, when the HO turns on the AC, breakers trip in six other mobile homes. In the offending mobile home, no breakers trip.

Each feeder has a 60 amp 2 pole breaker. Each pole of the 60 A brkr. serves two trailers. In other words, a 60 amp 2 pole Pushmatic breaker serves 4 mobile homes.
Click to expand...
So, it seems that the breakers FOR the other trailers tripped, not the breakers IN the other trailers.

Mystery solved. Maybe. ;)
 
Sorry to get you guys wound up for nothing. Friday afternoon, this call seemed like it might have been a tough one. Thanks for the help. You guys made me the service man I am (and I still have miles to go!).
 
See how easy some calls turn out to be.None of us could have guessed this as the outcome.Now see if you can turn this service call into a million dollar repair.Our company did once.
 
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