NFPA 79 and disconnect

[megloff11x]

NFPA 79 Chapter 6 is pretty clear on wanting power pulled when you open a panel, but I want to be sure there isn't another provision to work around. I'll have a panel full of heater controller and motor starters. You'd have to work at it to touch live Voltage - most likely you would need a screw driver. It's to be largely maintenance free. They would like to not have a door, but rather screw the lid shut and at worst have a key lock installed rather than a main disconnect switch. It's a space issue. The box will also be a plug in appliance.

Am I missing an exception or should I stay with the disconnect interlock on the access panel? Will a warning label suffice?

Again, I'd prefer to have the power disconnect, but they're pressed for space, and I've dealt with any number of machines and equipment that did not have power removal when you open the doors to the electronics.

Basically what I'm asking is for confirmation that they need the power removal interlock on the panel and that I haven't missed an exception to that rule.

Thanks

Matt

 

[todd99]

Matt,
I know of no exception, assuming you are talking about voltage above 50V. Furthermore, I wouldn?t even want to look for an exception. This is for the safety of the personnel involved and IMO you are asking for trouble without a main disconnect in or at least adjacent to your controller and interlocked (70E compliance, lock out-tag out etc.).

And please do not let someone compromise your design because there's not enough room for the equipment needed.

I certainly would not want to tell an OSHA agent or other official that we created an unsafe situation because of limited space.

Todd

 

[megloff11x]

I agree. Whenever this comes up, they point to stuff older than I am that has no door interlocks. I'm just covering my bases not wanting them to find an exception that I missed.

It would be pretty hard to touch live parts in this but those who do end up shocking themselves usually find a way around everything.

Bad memories of a story my Dad told about a guy who sawed off a finger. He showed the OSHA guy how he had defeated all of the interlocks on the tool with tape and bailing wire and then lopped off another finger while demonstrating this!

Matt