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 Post subject: Opening Door on Breaker Compartment
PostPosted: Wed Oct 13, 2010 5:38 am 
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Location: Rutland, VT
In a previous thread, "Flash, Flash Boundaries", there was a comment on is opening a door considered "interacting" with the equipment and is AF PPE required? In the particular context, this was for a medium voltage, GE MagnaBlast (gotta love the name in this arc flash arena), whether opening a door with the breaker opened, racked down and shutters closed required PPE. It may useful for a discussion on this point.

Now, playing devils advocate for discussion purposes, why would open the door, in this case be considered interacting with a piece of equipment? How could the door cause an arc flash event?

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PostPosted: Wed Oct 13, 2010 5:57 am 
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Here are my thoughts on this:

Some breakers have a "door interlock", which trips the breaker when you open the door. Late 70's early 80's vintage Westinghouse gear for example, I always thought it was one of the dumbest design ideas ever but they are out there, and without being equipment specific 70E needs to cover thier bases.

On MV gear with electro-mechanical relays a mechanical shock can cause the relays to trip the breaker.

Older breakers can also have exposed energized parts when you open the doors.

Improper trip latch adjustments can have some breakers mechs just a hair away from tripping, the slightest vibration can cause a trip.

These may be some of the reasons behind the thinking of the commitee. Do I feel comfortable opening a door without PPE? Sure I do, maybe stupid on my part but I know what to look for, but the way I interpret the 70E is PPE is required (As you explained in your post).


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