EMT Clearance from Knob & Tube

[DSamson]

I'm replacing an old fuse panel in a hallway closet with a circuit breaker panel in the hallway nearby. To extend and relocate the old branch circuits, I need to run EMT between the old fuse panel and the new circuit breaker panel.

The EMT needs to go right by some old Knob & Tube (K & T). Most of the conductors in the old K&T are Type TW and are in loom in the relevant area. Some of it is Type R, wihtout loom in certain places (i.e., along the inside face of a stud, between knobs).

Are there minumum clearances required between K&T and EMT? Code section?

Can I go zero clearance if I make sure all of the conductors in question are covered with loom?

If not, is there another insulating material available that would make this proximity permissble?

Thanks, as always for the great help you all provide.

 

[ramsy]

Look at NEC 394.19 & 398.19

 

[al hildenbrand]

Can I go zero clearance if I make sure all of the conductors in question are covered with loom?

Yes.

The problem created by EMT is identical to the problem that accompanies old gas lighting piping. The Code references that Ramsey lists are spot on.

If you have ever noticed open wire K&T running between insulators (knobs) where they cross a gas line, you'll recall a 4" or longer length of loom with both of its ends friction taped to the conductor, and centered on the gas line.

 

[infinity]

I'm guess that the NEC is worried about abrasion from the metal conduit. Seems rather strange considering the the conductor is permitted to be inside of the conduit.

 

[al hildenbrand]

I'm guess that the NEC is worried about abrasion from the metal conduit. Seems rather strange considering the the conductor is permitted to be inside of the conduit.

I've seen these installations with the wire pinched by other material against the grounded pipe. Without the additional protection of the loom, the insulation could easily displace.

 

[marcb]

[quote394.19 Clearances
(A) General A clearance of not less than 75 mm (3 in.) shall be maintained between conductors and a clearance of not less than 25 mm (1 in.) between the conductor and the surface over which it passes.
(B) Limited Conductor Space Where space is too limited to provide these minimum clearances, such as at meters, panelboards, outlets, and switch points, the individual conductors shall be enclosed in flexible nonmetallic tubing, which shall be continuous in length between the last support and the enclosure or terminal point.
(C) Clearance from Piping, Exposed Conductors, and So Forth Conductors shall comply with 398.19 for clearances from other exposed conductors, piping, and so forth.=ramsy]Look at NEC 394.19 & 398.19[/quote]
I hope this helps398.19 Clearances
Open conductors shall be separated at least 50 mm (2 in.) from metal raceways, piping, or other conducting material, and from any exposed lighting, power, or signaling conductor, or shall be separated therefrom by a continuous and firmly fixed nonconductor in addition to the insulation of the conductor. Where any insulating tube is used, it shall be secured at the ends. Where practicable, conductors shall pass over rather than under any piping subject to leakage or accumulations of moisture.

 

[LarryFine]

I'm guess that the NEC is worried about abrasion from the metal conduit. Seems rather strange considering the the conductor is permitted to be inside of the conduit.

Not so strange if you look at conduit as I do; not only does it protect the conductors from damage, it also protects the building and its occupants from the wiring.