Have you ever re-set a circuit breaker without checking to see why it tripped first?

• Yes
• No

Guilty! I know I am not suppose to but it is still a very common practice.

So much for the 70E requirement about:

...the circuit shall not be manually reenergized until it has been determined that the equipment and circuit can be safely energized.

Yep, I'm guilty too.

I quote the OSHA reference this violates all the time, and yes I have done it before I knew better. In the Navy we did all sorts of things we should not have done, I had to do testing once to see how far out of phase we could parallel two generators before one blew up, that was fun (13 degrees).

Yep, done it at home when I was 15.

And the magical smoke (which make all electric and electronics work as steam-machine) went out of the breaker the second time (because it tripped a second time in about 2 seconds when I reset it the first one, so I gave it a second try and poof...).

Turned out to be a loose wire in the dryer's socket in the wall. A good ground fault if I judge by the opening time.

I know better now.

DB-25: was this acceptable or not?

Grey area to me, folks.

We have a DB-25 breaker that tripped today. Fed from a cable that has arc flash energy at 49 cal/cm^2. It is in a (heavy!) steel can, with a bolted cover, with a small plexiglas window to view the status of close/trip.

We knew it was 49 cal going into this thing, and we had a suspicion but were not 100% sure what caused the trip.

We decided to attempt a close (which it did successfully), by closing the handle by standing way to the side of the can, so an internal explosion would not blow directly on the person closing the breaker.

Most of our breakers like this, require you to open the box and reset the breaker mech before closing. We never allow this. But in this case, we decided to proceed, and proved that the mech on this breaker did not require it to be opened, and reset.

What do you all think? My electricians have given me hxxx o) for doing this. Longer term, we have a plan to reduce the energy below 8 cal/cm^2 using a fast relay sensing seconary current to trip the primary breaker on this load center. But, as usual, arc flash is a grey area to me, and to many as I view this forum.

Db-25

Forgot to state, that the other 2 options were:

1) open an overhead 23kv switch in the rain in cat 4 clothes, unable to fully remove all load from it, to de-energize the load center (and kill 3 other load centers at the same time). We have done this before, but this is not a wise thing to do on a frequent basis, even though calculated energy is supposedly less than 8 cal/cm^2.

2) open the main breaker feeding 1/3 of the plant, including the dept. that creates huge environmental problems for us when it is tripped without days of planning.

What type of trip unit is on this?

Reset what? Usually something that can be an easy fix.



I think you need a remote operator

DB-25 reset



DB-25 was retrofitted with an AC Pro in the past couple years. Reset of all of our other can mounted DB-25's with Carriere solid state trip units requires you to open the can, push a trip mechanism reset button, then close the can. We looked at buying a chicken switch or equivalent a few years ago, but the chicken switch, at the time, did not have the torque to operate the handle on a DB-25.

We have decided to install a small 5 kv draw out vacuum breaker on the load center primary with a Schweitzer 751a optical sense relay with transformer secondary CT's to solve the problem once and for all.

Yes the AC PRO's have an available electric reset actuator but most people seem to cheap out and use the manual reset actuator, saves a whole $100. Not much that can be done about the carriere ones, don't think they offer an auto reset.

Chicken switch does not offer many options, we build a unit specific to the DB-25 and 50's that will charge, close, and trip them wirelessly. I will email you info on it.