Dead Front Definition Abuse

[infinity]

I've been having a discussion with someone about the use of the NEC term dead front. Seems like almost everyone thinks that a panel cover is the dead front yet the definition in Article 100 doesn't really support that it actually describing a metal cover. I've heard others say that it's the inner portion of a cover on commercial style panels where there are two separate sections. That doesn't meet the definition either because you can still stick your hand in the panel and access the energized parts. IMO the "dead front" is not a physical piece of anything as it is a condition created by the use of a panel cover. Opinions?

The Article 100 definition:

Dead Front.
Without live parts exposed to a person on the operating side of the equipment.

 

[wwhitney]

Correct, per the definition, "dead front" is an adjective, not a noun.

Cheers, Wayne

 

[charlie b]

IMO the "dead front" is not a physical piece of anything as it is a condition created by the use of a panel cover. Opinions?

I agree with this and I like Wayne's explanation. Can anyone give an example of a "live front" condition?

 

[electrofelon]

I agree with this and I like Wayne's explanation. Can anyone give an example of a "live front" condition?

Not very common these days. I think in the beginning equipment was like that.

 

[infinity]

I agree with this and I like Wayne's explanation. Can anyone give an example of a "live front" condition?

I think that an old switchboard with exposed knife switches would be a live front.

 

[OldBroadcastTech]

"Throw the THIRD switch..............'

 

[infinity]

I remember working on original 1930's open switchboards in Rockefeller Center where they had begun to replace them in the 80's. Scary stuff.

 

[LarryFine]

"Throw the THIRD switch..............'

And stenciled over the third switch was "THE WORKS."

 

[OldBroadcastTech]

Thank you

I tried to isolate the pictures but no luck here.

 

[electrofelon]

I remember working on original 1930's open switchboards in Rockefeller Center where they had begun to replace them in the 80's. Scary stuff.

I like how they thought that was ok for a while. "The handle of the knife switch is insulated, what else do you want???"

 

[jim dungar]

"The handle of the knife switch is insulated, what else do you want???

This why disconnect switches are called 'safety switches'. Enclosing open style blade switches is what led to a company changing their name to Square D.

 

[kwired]

I agree with this and I like Wayne's explanation. Can anyone give an example of a "live front" condition?

go back 100 plus years where exposed equipment was more common and they maybe didn't call it live front but at some point when they started enclosing things more the term dead front became a thing.

Maybe can even go back to where there may been a cabinet door but opening it to access switches or overcurrent devices still resulted in exposure to live components. Today there isn't really that much that you open a door for rather routine tasks and are exposed to live components without having to remove an additional cover. Some safety switches yes. Most anymore won't open without turning them off or bypassing the latching feature, if equipped with such a bypass.

Open components are still common on medium and high voltage equipment but protection is usually via elevation and/or limited access to only qualified persons.

 

[tortuga]

I agree with @infinity; here a example of a switch board that does not have a dead front:

 

[OldBroadcastTech]

and how about the 'maneuvering room' switchgear in WW2 subs ?

Holy Hand Grenade of Antioch !!

240 volts at 3-4000 amps