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Posts Tagged ‘obsolete circuit breaker’

Obsolete Circuit Breaker – When maintenance does more harm than good

May 21st, 2010 Comments off

Frequently MIDWEST maintains and tests old and obsolete circuit breakers on the customer’s site.  And frequently the customer has their electricians or outside electricians remove the breakers from service and bring them to our breaker testing setup site. We are strong advocates of maintaining old and even obsolete circuit breakers.  In addition to routine or textbook procedures, we have additional special maintenance services on older equipment.  This is especially true when outdated breakers have obsolete overcurrent devices. We know how to repair many of the common deficiencies that we find in old breakers.  But there is one common defect that suggests one may do more harm than good by removing breakers to test and maintain them. This occurs when insulating components, such as the old plastic or Bakelite supports for control disconnect fingers, are broken by the manhandling required to get the breakers out of their enclosure, to the test station, and back.  We instruct the electricians on the cautions necessary, but it can be a challenge if you’re hauling a 150 pound breaker down a staircase.  And many times these vulnerable components are installed on the breakers at “just the wrong place,” like on the bottom of the breaker where you don’t even see them, unless you know they are there.  MIDWEST is extremely careful and we know what can happen, so we are better equipment to prevent problems. But there are some obsolete breakers located in such miserable areas, that one could nearly guarantee more damage is going to be done by the customer’s riggers or electricians moving the breakers than the typical deficiencies we find from the routine testing and maintenance services. It may be better to maintain the breakers in their substations and not haul them to a separate test site.  This problem usually occurs when old or obsolete breakers are high current tested and the test equipped can not be located near the switchboard.

Shocking Circuit Breaker with Broken Handles

April 2nd, 2010 Comments off

MIDWEST has seen about every old obsolete circuit breaker there is.  We worry about the dangers of some breakers to those not familiar with circuit breakers. Some of these dangers are not present very often, but when they are, they could be lethal.  Here is a quick example of one such danger with molded case circuit breakers.  These are the plastic looking circuit breakers.  This danger usually occurs with three phase breakers.  The breakers have a plastic like toggle that is pushed up and down to turn a circuit breaker on and off.  Some circuit breakers with this toggle like handle are designed such that there is a metal stud that extends from the breaker into the toggle to give it support.  Occasionally the toggle breaks off leaving a visible metal stud sticking out from the front of the now defective circuit breaker.  This metal stud looks innocent enough.  You might even be tempted to use a tool on the stud to turn the breaker off or on.  Don’t.  On some breakers, the metal stud is actually energized at the full voltage of the middle phase.  That’s right, the metal stud is hot.  Shocking! And if you get between it and ground, you could be killed.  Whether old, new, or obsolete, if you find a breaker with a broker handle and there is an exposed metal stud, have a qualified electrician check it out.  The exposed stud would be hot when the breaker is closed, not when it is open, unless the breaker is back fed.  This is shocking news about some circuit breakers with broken handles.