Archive

Posts Tagged ‘danger’

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.    

Breaking It Down

April 29th, 2009 Comments off

Molded Case Circuit Breaker
Buy Molded Case Circuit Breakers

When budgetary concerns push back maintenance schedules

By Jason Honick

 

 

Circuit Breakers, that little invention designed to protect your electrical circuits. The way they work is when fault levels reach specific set points they are designed to open the circuit, thereby protecting personnel and equipment on the circuit.  Easy enough.

 

If fault points are reached and a breaker fails to trip, the viability of the circuit is put at increased risk. To breaker function, time is a thief. Trip units age, contacts pit and burn, operating mechanisms get stiff. The best hedge against these aging effects is good preventative maintenance as you might have guessed. And as you also might have guessed, here at MIDWEST we perform breaker testing and maintenance.

 

No one knows the value of good maintenance more than maintenance people. If you’ve ever had a circuit go out due to a defective breaker, you know it’s something to be avoided. The costs involved in terms of safety, equipment replacement, and down time can be staggering. In the best circumstance, good engineering weighs the risk-benefits associated with good maintenance. But as often the case, real world circumstance doesn’t always allow for such luxury.  Budgets get squeezed, priorities get changed, production schedules jam up. So where does that leave the prudent minded maintenance professional. Out in the dark? Not so fast. There are things one can do to minimize the risk of putting-off breaker maintenance programs.

 

Exercising or operating the breaker (a minimum of five times), as simple as that may sound, is a proven technique to keep the mechanics of your breaker running smoothly and help stave off the bad effects of idleness. Breaker contacts are designed to “wipe” themselves while closing. As the breakers closes, a slight lateral action occurs between breaker stationary and movable contacts as they come into contact with each other. This action cleans contact surfaces. Exercising the breaker also keeps current carrying pivot points in good shape. On the extreme, we’ve seen breakers whose mechanisms have become so stiff from lack of exercise they failed to open when tripped.

 

Exercising a breaker does require the circuit to be opened if only temporarily which can often be scheduled in “slack times” or “window of opportunity times”.

 

Happy exercising.