Inner door panels

[brinkmann27]

We are manufacturering a NEMA 4 control panel with an "inner door" (a door inside the enclosure) The inner door has H-O-A switches, pilot lights, hourmeters and ampmeters. Usually we make cutouts for the circuit breakers or Manual motor protectors whereas you can reset them without opening the inner door. Looks nice but is a pain to do, especially with breakers/MMP's of different heights.

Question.....how many of you do this (make the cutouts) or do you not cutout the inner door?
Then require the inner door to be opened to reset them.

As access to the CB's/MMP's isn't normally required to operate the system is the cutout a waste of time?

Is there any code that addresses these inner doors?

Thanks!!

 

[buzzp]

We typically do not have CBs or disconnects on the inner door. However, the HOA's and other low voltage controls, we always mount on the inner door unless the customer wanted something else. I am speaking based on my experience in the oil patch. Dont believe this is addressed in any standard other than best practices, dont recall the IEEE or IEC number.

 

[brinkmann27]

The CB's/MMP's are mounted on a bracket which is mounted on the enclosure back panel. (not on the inner door). The inner door cutout gives access to the breaker face and trip handle.

 

[dbaird]

Just my thoughts---->I would consider the cutouts a waste of time. I assume your inner door is hinged to swing out anyway and if/when the breakers need reset (not often) the inner door swings open to alow resetting of the breakers. Not a big deal and doesn't happen enough to justify the cutouts.

Maybe I'm missing something?

David Baird
mrbaird@hotmail.com
Sr Controls Engineer
EET degree.
Journeyman Electrician.

 

[mckywood]

Our plant is trying to come in compliance with the OSHA reg. on arc. Flash So puting in the inner door with cutouts makes sense to me.

 

[brinkmann27]

David, yes the inner door swings open allowing the CB's to be turned on or off. (I don't think your missing anything)

mckywood, what OSHA reg. are you trying to comply with that requires an inner door with cutouts?

Thanks again

 

[mckywood]

Actually it is the NFPA 70E-2000 About worker safty from Arc flash. In order to open a energized panel it is required for us to have protective cloths, gloves and sometimes the arc. shield for eye protection. (Depending on the voltage.)Because of this we can not open a 480 vac panel without full gear on just to reset a breaker.
having the cutouts should give us that extra protection so maybe we would not have to suit up for such problems.

 

[dbaird]

Seems to me that a cutout large enough to alow resetting a circuit breaker would also be large enough to let through arc flash. Would it not, at minimum, have to be tested and approved by the appropriate agency(UL/NEMA)to become an exception to PPE against arc flash? In this case, is the inner door with cutouts an approved method/shield against arc flash?

David Baird
mrbaird@hotmail.com
Sr Controls Engineer
EET degree.
Journeyman Electrician.

 

[jraef]

The arc-flash issue is not being thoroughly enforced as yet from what I see, but the scuttle-butt is that it is "coming soon to a theater near you!" I have heard that inspectors are getting training on this issue, but dbaird makes a good point, that without a testing authority and related test standard to adhere to, it is a bit too nebulous for full enforcement at the moment IMHO.

brinkmann27,
What I did (when I was designing panels) for the motor breakers or manual motor protectors, was to use their through-door operating mechanism, but remove the door interlocking components so that the door could be opened for testing/troubleshooting without needing to turn off those devices first. We always had a main CB that WAS interlocked with the door so that only authorized technicians could have access, but with the new arc flash regs, I don't see that being allowed any longer either.

I have observed many panels over the years where the motor protection devices have had cut-outs in the door so that their basic handles extended through, but I agree that it is a pain to make those cuts. One thing I have seen, but never used, was a special punch set for a hydraulic punch that made the correct shaped hole for a Seimens MPS in one operation. I don't know if that punch and die set was custom made or available off-the-shelf, but it was with a Haewa punch system.

http://www.haewacorp.com/More Products.htm

The other trick, if you don't already know it, for odd shaped cutouts like that is to use a plasma cutter and a steel template. We did that for meters and instrumentation devices that we used frequently and it makes it a breeze IF you already have the plasma cutter.

"Venditori de oleum-vipera non vigere excordis populi"