EMT SLEEVES

[michael nye]

I am an inspector for the city of Susanville Ca Building Dept. On a tract home project the Electrical contractor uses a 2 inch metal conduit to sleeve through the Fire Wall. The romex that is going through the pipe, you can see the little pieces of plastic that have been rubbed on the edge of the EMT, my concern is the conduit could become energized, and it would seem a bushing and or grounding the pipe should be a given.

 

[bennie]

Re: EMT SLEEVES

The sleeve should be reamed at each end. Grounding this piece seems unnecessary.

 

[bonding jumper]

Re: EMT SLEEVES

well, reaming is would help, but the reason for grounding would be because the wire that is already in the pipe is chaffed. So thats is why grounding is suggested. Maybe just replace the chaffed wire & ream the pipe would be the best method.

 

[bennie]

Re: EMT SLEEVES

Why a sleeve in a tract home wall?

 

[rrrusty]

Re: EMT SLEEVES

I take it there were no fittings on the ends of the EMT?

 

[renosteinke]

Re: EMT SLEEVES

This might be a hard one to cite...
Trade practice is to install a bushing or fitting on the ends of the pipe to prevent this chafing. A small sleeve, that is generally inaccessible, is typically not grounded (IE, metal elbows used to re-inforce pvc elbows underground).
Many UL standards require that wires passing through parts of appliances be protected from chafing in some manner.
Simply reaming the EMT is often not enough to prevent this chafing.
The "putty" used to seal the pipe should prevent chafing caused by vibration.

 

[charlie k.]

Re: EMT SLEEVES

Quick and easy solution, I agree with Bennie grounding is no needed. Install insuliners bt T&B. These will snap in even with cable in sleeve.

 

[bennie]

Re: EMT SLEEVES

The danger of grounding this sleeve, is a arcing fault can develop and make the sleeve a fire wall igniter.

 

[michael nye]

Re: EMT SLEEVES

bennie please explain the possible fire scenario, it does pass through the fire wall but if grounded the circuit would trip, no?

 

[bennie]

Re: EMT SLEEVES

Michael: The NM cable sheath and THHN insulation would be slow in wearing through. The initial contact would be with light pressure. The contact would likely arc, extinguish, and restrike, instead of being a solid connection to cause the breaker to open.

This scenario is only my speculation, it is not based on any acceptable research.

 

[michael nye]

Re: EMT SLEEVES

Bennie, I understand, in other words the short being light would blow free,just making it a momentary sparkler. Thanks, I think the bushing setup is the best to mandate, inexpensive for the contractor, and maintains the firewall protection. Thanks guys your the bomb.