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#191491 12/31/09 03:51 AM
Joined: Mar 2005
Posts: 240
Member
I am reading art 430 trying to determine if I can upsize my breaker. I have a service call for a septic grinder which keeps tripping the breaker and setting off high limit alarm.
I don't know any of the specs for the motor(not going to scrape feces off nameplate to find out :-)) What I do know is the running current is 12.5 amps and the start up is about 31 amps, it is protected at 20 amps now and want to change 2 pole breaker to a 25 amp.
Thanks,
H20

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Joined: Aug 2007
Posts: 853
L
Member
1st,I has it been determined that the motor/conductors are ok?
Depending on the cycle times,the breaker may just be getting tired.

Then get into the OCPD.

Joined: Jan 2005
Posts: 5,316
Cat Servant
Member
Breaker getting tired? frown

How about there maybe being a problem with the pump?

The control panel ought to have a sticker or at least manuals for the pumps, giving you the normal FLA. Otherwise, the size of the contactor can give you an idea of the maximum amount of current the panel can handle. Personally, I'll bet you're exceeding the proper limits.

Grinder pump or not, the first likely cause of troublr is stringy material getting into the pump and wrapping itself around the shaft. If the pump is 3 phase, you can run it backwards and see if that clears the problem.

Next on the list are bad bearings on the pump. When you pump the pit down, you'll likely hear noise once the motor is exposed. Alternatively, you might be able to feel vibrations as the pump runs.

There's no avoiding someone getting down in the pit. If that someone is you, consider getting vaccinated against hepatitis.

Joined: Apr 2002
Posts: 7,298
Likes: 6
Member
Is the 'trip' happening on start-up, or running?? Without info or details on pump it's a 'guess' opinion. 230 volt, single phase??

12.5A running w/20A OCP sounds 'right' IF trip is only on start, and contacts, etc. are OK, try the 25 while you're there to observe.



John
Joined: Mar 2005
Posts: 240
Member
Hotline it is 230 volt, tripping is at start up. This motor is fed through a float, so there is no motor control, the control is strictly for high alarm. I will change breaker to 25 amp, just not sure if it's legal, since I don't know what the nameplate is, or if the motor has overload protection(which excludes the exception of next size up).

Reno, I have heard that the hepatitis shot they give you, is for one form of it. And there are several types, so I gotta draw the line and say "No way!" Bearings could be, don't think anything is caught in motor, but will check with septic guy that inspected pump prior to my service call(they are not licensed for electrical).

Leland, conductors should be fine, it is overcurrent tripping not short circuit.

Thanks guys,
this website is very helpful.
H20

Joined: Jan 2005
Posts: 5,316
Cat Servant
Member
It's a shame that you're not there together with the plumber; that's the way to do these jobs. Oh well.

You need to pull the pump to check the impeller for foreign crud. The first step is to try to spin it by hand; if it feels harder than is should be, some disassembly will be required to clear the pump. This is not always practical in the field.

You are correct in that there are several types of hepatitis. However, there is only one that is transmitted by contact with sewage; that's the one you get the shot for. Your MD can keep all the types straight. Just day "no, Doc, I'm not a junkie, I work with sewage" and he'll know which vaccine to use.

Joined: Aug 2007
Posts: 853
L
Member
Breaker getting tired? frown

Technical? No. But I have seen it on these types of ckts.
Also it was not my 1st choice.

I'll try harder next time blush thumbs

Joined: Mar 2005
Posts: 212
G
Member
Slightly off subject, but be aware, hepatitis is not airborne transmittable. Cover your skin, wear a mask, take a shower, you'll be OK. Not happy, but OK.

Joined: Jul 2007
Posts: 1,335
S
Member
If the pump in plugged into a receptacle then the breaker can not execeed the requirement on NEC 240.4(D)


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