Evaluating Fire Damaged Wiring?

[mdshunk]

There seems to be a lot of industry guidance on the evaluation of water damaged cables, but not so much on fire, heat, and smoke damaged cables and conductors. Does anyone have a link to any paper that would provide some guidance? I know that cables that are visually only "smoked" or maybe not even visually damaged at all can be really hard to skin out, which I take as evidence of heat stress (insulation cooked on to the conductor). How's a guy to know, visually?

 

[Minuteman]

Good question Marc. Now that you asked, I would like to know as well.

Typically, if the wire passes the megger test and looks okay to me, I leave it. If the wire is accessible and slightly discolored or worse, I splice in new wire. However, if the repair scope does not include demo of a wall portion, and the wire passes a megger and visual test, I have no grounds to change the scope.

FWIW, It's the same thing to me with wire pulled in conduit.

 

[brian john]

One issue to be concerned with is soot on the conductor insulation, strictly meggering the conductor may not show anything, should the insulation lay against bus there could be an issue. Any insulating material needs to be clean.

Visually if the insulation looks damaged I recommend replacement. If you have any questions or in doubt recommend replacement, if the custom disagrees you have recommended whats best in their interest.

 

[Len]

Fire (heat) damage wire

Fire (heat) damage wire

I just was called out on a kitchen fire, I called my inspector and asked him this ? His answer was simple. When you have alot of heat from a fire the insulation around the copper wire can loosen causing a loss in the integerity of the protection provided. Any time you have a fire all wiring in the area of the fire should be replaced.

 

[480sparky]

And not just in the room of the fire, either.

I recall a job I did years ago. Pool room of an apartment building. Pump had caught fire, and the flames and smoke were limited to that room.

But the heat got up into the ceiling, and other areas of the building had wiring damage. I was opening boxes 50 to 60 feet away from the fire and still finding wires with damage. Mainly brittle insulation.

What the boss figured to be a half-day fix turned into a 6-day nightmare.

 

[Minuteman]

I just was called out on a kitchen fire, I called my inspector and asked him this ? His answer was simple. When you have alot of heat from a fire the insulation around the copper wire can loosen causing a loss in the integerity of the protection provided. Any time you have a fire all wiring in the area of the fire should be replaced.

Agreed. Some fires equal total rewire. Some equal only the AREA near the fire. Some have a lot of heat. Nothing cookie cutter about fires.

This last fire we are doing was mostly smoke. Garage had no outlet for GDO and HO used an extension cord. Up the wall, through a hole in the ceiling, across the attic, through another hoe, to the GDO, Cord overheated and caught something on fire in the attic. What ever it was, smoked the place up real bad. GC had to replace all the sheetrock, insulation, and sheathing. Had to knock down the brick to re-sheath. We did a total rewire and 95% of the wire looked good.

BTW, I LOVE rabbit!