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Old 04-25-2019, 09:11 AM   #1
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Default Troubleshoot this

I have two 208V appliances in a restaurant (recent build) on 30 amp breakers. Both breakers tripped a couple of times over the last couple of weeks. Yesterday they tripped five times.

I am getting 22.5 amps on each with a clamp meter. I have been here for an hour and nothing has changed. What now, gurus?
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Old 04-25-2019, 09:14 AM   #2
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More info needed.

What are the appliances?
Did you check to make sure that there are no bastard splices between the two circuits?
Both breakers trip together every time?
When the breakers trip, are both appliances always running?
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Old 04-25-2019, 09:22 AM   #3
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Quote:
Originally Posted by HackWork View Post
More info needed.

What are the appliances?
Did you check to make sure that there are no bastard splices between the two circuits?
Both breakers trip together every time?
When the breakers trip, are both appliances always running?
Shawarmas.

They will trip independently.

Both are running at the same time when tripping occurs.
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Old 04-25-2019, 09:26 AM   #4
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Just a hunch, but both those breakers were bought at the same time and same place, could be a batch of defective breakers and lucky you, you got em IDK. I check easy first.
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Old 04-25-2019, 09:36 AM   #5
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Just a hunch, but both those breakers were bought at the same time and same place, could be a batch of defective breakers and lucky you, you got em IDK. I check easy first.
Could be a breaker issue. There was a dummy (me) who shorted them out during finishing. Maybe weakened the breakers?
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Old 04-25-2019, 09:41 AM   #6
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Quote:
Originally Posted by 99cents View Post
Could be a breaker issue. There was a dummy (me) who shorted them out during finishing. Maybe weakened the breakers?
Shorted both breakers out? How did you do that?

And yeah, replacing breakers is a good idea in these situations, especially after you had an issue with them.
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Old 04-25-2019, 09:42 AM   #7
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are the breakers side by side? if so it could be the ambient temp at the breakers. whats your measured voltage?
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Old 04-25-2019, 09:53 AM   #8
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Originally Posted by HackWork View Post
Shorted both breakers out? How did you do that?

And yeah, replacing breakers is a good idea in these situations, especially after you had an issue with them.
Fast track job, working nights, things happen.
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Old 04-25-2019, 09:55 AM   #9
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are the breakers side by side? if so it could be the ambient temp at the breakers. whats your measured voltage?
Not side by side, voltage is good.

Breakers are warm to the touch compared to the others.
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Old 04-25-2019, 10:11 AM   #10
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Quote:
Originally Posted by 99cents View Post
Could be a breaker issue. There was a dummy (me) who shorted them out during finishing. Maybe weakened the breakers?
IF, i were to short out a breaker, I wouldn't short across the phases. Only short 1 phase to ground.
Like i said, IF lol
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Old 04-25-2019, 10:13 AM   #11
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At a 22.5 amp continuos load, on a 30 amp breaker, the breakers will probably be a little warm. Do you have a amp meter with peak capture? If everything else is working fine, the two options are the equipment is defective or the breakers trip is off a little.

Do a "fall of potential test" across the breakers to see if one or more poles has a higher resistance than the other. I would be concerned if the FOP test showed more than a 50 milivolt reading.

Probably replace the breakers and see if anything changes. If not, probably an equipment problem.

Also, do the FOP test between the panel incoming line terminals and the problem breakers load terminals. This would verify the panel buss connections and the breaker contacts.
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Old 04-25-2019, 11:22 AM   #12
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Quote:
Originally Posted by 99cents View Post
Shawarmas.

They will trip independently.

Both are running at the same time when tripping occurs.
So, same manufacturer? Any way to find out if this equipment causes these problems? Is this new equipment? Are they hardwired? If not what do the plug & receptacle look like?
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Old 04-25-2019, 12:04 PM   #13
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Any chance that the 2 sets of wires got mixed (same pipe same colors)???
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Old 04-25-2019, 12:09 PM   #14
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are they cutting meat and in turn loading the motor when it trips?
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Old 04-25-2019, 12:12 PM   #15
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What's your incoming voltage when the Donair place is hopping. Could the voltage be dropping just enough to raise the current close to the trip level?


Tim.
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Old 04-25-2019, 12:21 PM   #16
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Quote:
Originally Posted by AU Facilities View Post
Any chance that the 2 sets of wires got mixed (same pipe same colors)???
Possible but unlikely. I will verify before I go back with the new breakers.

Used machines with factory cords (maybe). Normal 30 amp dryer receptacle.

One tripped just before I left so nobody was cutting meat at the time.
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Old 04-25-2019, 02:39 PM   #17
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Just a hunch, so it’s a commercial kitchen, cord and plug.
Maybe not a current issue, assuming they are gfi as required by code, my bet is it’s in the equipment,and it’s tripping out on the GFCI function. probably from moisture from cleaning or steam from cooking.
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Old 04-25-2019, 02:56 PM   #18
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Just a hunch, so it’s a commercial kitchen, cord and plug.
Maybe not a current issue, assuming they are gfi as required by code, my bet is it’s in the equipment,and it’s tripping out on the GFCI function. probably from moisture from cleaning or steam from cooking.
That’s a good thought. The receptacle box might be filled up w/water or goo is built up btw plug blades, etc.
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Old 04-25-2019, 03:13 PM   #19
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Quote:
Originally Posted by 99cents View Post
Could be a breaker issue. There was a dummy (me) who shorted them out during finishing. Maybe weakened the breakers?
As noted do an FOP
This load is resistive with a motor after start up the current should be fairly constant

Tt 22.5 amps you are close to the magic number of 24 WHICH might put you close to the longtime trip.

Not tripping now because the cover is off?

Put a cover on and put a fan in front of them see what happens

OR replace the CB's
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Old 04-25-2019, 03:22 PM   #20
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I've seen thermal magnetic breakers trip after a restive load runs for a while because the load is approaching the threshold and the breaker warms up, eventually opening. If you have a means to monitor the temperature of that breaker as the load is started and as it continues until it trips, that may give you some indication.

Maybe lift the breaker and make sure it's seating on the bus well.

Old grease saturated junk like is common in an old restaurant? Or is this new work?
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