Posts Tagged ‘water damaged circuit breakers’

All Wet Circuit Breakers

July 12th, 2010 Comments off
TJJ436300 General Electric Circuit Breaker

TJJ436300 General Electric Circuit Breaker

MIDWEST buys surplus, old, used, obsolete, and even ugly circuit breakers.  We are paranoid about the history and condition of these previously owned circuit breakers.  We are particularly concerned someone will try to sell us breakers that look good, but have been damaged by water.  We are especially cautious because of dramatic flooding in recent years. This week we got a call asking us if we wanted to buy like new circuit breakers that were flooded with water.  Our polite answer was a screaming “No!”  They were honest and told us the breakers had been flooded.  We will not even consider buying moisture damaged circuit breakers. They could even be brand new circuit breakers and still, no. 


These breakers could be cleaned up cosmetically so they look new and they might even pass the basic electrical tests, but we know they are still junk. If you tore a water damaged breaker completely apart, including the trip device and the operating mechanism, you would find rust and caked on dirt, even mud.  Under the stationary contacts, on the trip device hold down bolts, under the trip element, inside the trip element, everywhere in and under the operating mechanism.


The breaker may pass the insulation resistance tests, the contact resistance tests, and maybe even the over current tests. And, if you don’t bother to take the cover off, you might never know that the breaker was damaged by water or extreme humidity.  We know that plants that have been flooded will go through a thorough switchgear on site reconditioning process. Switchgear, including circuit breakers, will be restored to operating condition in an effort to get the power back on as quickly as possible. But these are emergency situations and getting replacement equipment quickly may not be possible.  So one should not compare such an extreme circumstance with the normal world of a Switchgear Service Shop. 


We want to know the history of equipment we purchase and we can not rely on that information being always accurate. Everything must be completely checked out, reconditioned.  And because equipment passes standardized tests, does not mean it is reliable for reuse.  Reconditioning will determine if it will be reliable after passing the standardize tests and MIDWEST’s other reliability centered tests. But testing alone does not determine reliability.

Disaster Replacement Circuit Breakers

June 25th, 2010 Comments off

An engineer called MIDWEST and asked how he could make sure a replacement for one of his old obsolete circuit breakers was not something out of one of the US disaster areas. He said it was a used replacement circuit breaker, but it looked shiny as new and seemed to operate okay. But he just had a bad feeling. To MIDWEST, that means he knows something he isn’t telling us. Regardless, here’s the short answer to his question. If you are qualified, remove the cover from the circuit breaker. Remove the arc chutes. On old circuit breakers, be careful, because the arc chutes may fall out in a dozen pieces. Remove the lugs.  Carefully remove the trip device.  Be sure not to lose any barriers or arc dividers. Then a close visual inspection must be made to detect any signs of corrosion or contamination on the breaker operating mechanism or inside the circuit breaker trip device or under the current carrying components. If the breaker got wet, corrosion should be easy to spot, but be sure to make a hard focused inspection.  Something more than a cosmetic look. During this process, look for signs that someone else has already tried to recondition the circuit breaker. Just cleaning a used or even a new circuit breaker, after it has been immersed in water, can be nearly impossible. There will be corrosion and dirt, even mud, in areas that are inaccessible. The trip device must be taken apart. MIDWEST has experience repairing old trip devices. It usually just isn’t worth the time. And if you mess with the trip element, there is a whole sequence of over current tests that must be performed afterwards. You can’t take a trip device apart, put it back together, and not completely test the circuit breaker afterwards. So, if you suspect an old, obsolete, or new circuit breaker has been exposed to water or mud, your best decision might be to destroy it and then throw it in the trash. Note, we strongly encourage destruction of any circuit breaker that is defective, so no one tries to reuse it. If you find nothing to indicate the breaker was damaged, then you have to put it all properly back together and test it.   

Water Damaged Circuit Breakers

October 12th, 2009 Comments off

1200 Amp Square D Circuit Breaker

Buy 1200 Amp Square D Circuit Breakers

We had a conversation with a maintenance mechanic.  He said he was a carpenter one day and an electrician the next, so he needed a little advice.  He had some plastic circuit breakers that got washed down during clean up and, after they dried off, they looked great.  But he wanted to know if he could still use them or if we could tell if they were okay.  They were small single pole circuit breakers, a couple 200 amp circuit breakers, and one 1200 amp breaker.  We call these molded case circuit breakers, but they are what everyone typically just calls circuit breakers.  They also had some old obsolete bus plugs and some small transformers used for emergencies, that he just threw out.  We told him to also throw out the little breakers and the 200 amp.  Actually we told him to smash them so nobody would be tempted to reuse them.  We have torn apart old and new circuit breakers after water damage and they are nasty inside.  You do not want to reuse them.  Very dangerous…  Even if they worked mechanically, they could easily fail to interrupt load and turn into fireworks.   We told him, if he wanted to, he could send us the 1200 amp breaker and we could take it apart and see if it could reliably be reconditioned.  The chances of that are less than 50%.  The real concern is whether or not the over current trip element in the circuit breaker got wet.  If it did, it is very time consuming to take it apart and restore it to perfect working condition.  And the quality control tests after the repair of a trip device are also time consuming.  Many new circuit breakers have electronics which make reliable reconditioning after water damage almost impossible.  One could do a simple clean up of a water damaged breaker and test it and it may pass all the simple routine tests.  But internal inspection shows immediately that the circuit breaker, especially the circuit breaker trip device, is not reliable.  We have seen water damaged used circuit breakers pass the basic insulation resistance, contact resistance, and over current tests, but fail our own additional special quality control tests. The internal inspection shows them to be in horrible condition.  We find rust, free water, mud, and usually slime.  If you have water damaged circuit breakers, just destroy them so no one thinks they are okay and tries to reuse them.