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What kinds of materials can cause damage to NM Insulation or wiring?

What kinds of materials can cause damage to NM Insulation or wiring?

Old 01-15-13, 11:05 PM
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What kinds of materials can cause damage to NM Insulation or wiring?

Hello all.
I am new to the forums.
I am a "recovering" Contractor.

My question specifically to do with a fire restoration job I am involved with.
The Owners suffered an electrical fire of undetermined cause that was traced to a metallic outlet box in the garage. The Fire department arrived quickly and contained the fire to the attached garage but in the process of checking the ceilings in every room of the house by "venting" (that is bashing a hole through the ceiling of each room with a fire axe to make sure there is not anything burning there) they allowed the smoke to damage the entire home and it's contents.

Oh well.

The Insurance coverage was more than ample to rebuild. The Contractor hired by the owner to do the restoration was also hired to do the restoration and repair of the contents and to mitigate the fire and smoke damage to the house. The Insurance adjuster identified and provided coverage to "seal the wall studs, floor and ceiling joists and framing, but never specified what it was to be sealed with. When the GC said they were going to use white pigmented shellac, I didn't see a problem with it as I had used that product as a sealer myself on painted surfaces that had been damaged by smoke such as plywood and drywall (after it had been cleaned, of course).

The problem occurred when the crew sent out to seal the framing didn't bring enough material with them when they came out to do the job (before HVAC and Electrical RI). Rather than finish a section or send someone to the paint store, they decided to "FOG" coat the entire frame. They ignored several requests by the owners to finish the sealing until AFTER all of the wiring and oulet, switch and fixture boxes had been roughed in. They basically shellaced
all of the wiring inside the house.

I remember Inspectors getting ticked at my painters for getting any type of paint or stain on the wires or their insulation because of problems it could cause. And that was latex (water Based) paint.

This is solid bodied white pigmented shellac. I thought "that can't be good" but I am having trouble finding any references on it.

Should I be worried? If so, about what and could you please if able cite the appropriate authorities. Also if you have any good links on fire restoration, that would be useful as well.

Thank You,

Old 01-16-13, 01:53 AM
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My only experience on a fire job, we roughed in after everything was sealed.
Old 01-16-13, 02:25 AM
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Yeah, that's what normal contractors do. The fact they shellac'd the wires has me concerned. I am worried that the insulation properties could be affected or that the insulation itself could break down as a result. I would appreciate it if anyone knows the link to a testing lab or some other industry organization that might have experience with this type of thing. I would hate to find out a couple years down the road the HARD way.
Old 01-16-13, 06:56 AM
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NMB wiring should have a PVC sheath. Looking at the MSDS for several of the white pigmented shellacs, the primary solvents are ethanol and propyl alcohol. PVC has very good resistance to both of these chemicals so I wouldn't worry that the Shellac broke down the sheathing.

Will an inspector pass electrical if all of the identifying marks on the wiring have been concealed? I thought one of the NEC requirements was that all wiring have proper identifying marks.
Old 01-16-13, 07:25 AM
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Welcome to the forums, Ursus!

This sounds like something to be concerned about, and to get resolved before the walls are closed. It also sounds like a technical question that can only be answered by people with specific knowledge of the materials used to make the outer sheath of Type NM-b cable and how that material might be affected by being coated with white pigmented shellac. There are several groups of folks who might have that expertise, and that you might want to contact:
  • Electrical industry and code experts such as Mike Holt;
  • Cable manufacturers including Southwire, the developer of Romexģ (contact info), and, if you used type NM-b made by a different manufacturer, the technical people at that company;
  • The company that manufactured the shellac;
  • The most experienced and knowledgeable home inspector you know;
  • The Fire Marshall's office; and, of course
  • The inspection office responsible for giving you the approval to close the walls.
I'm grateful that you're taking some time to check this out before proceeding. I hope your clients are too!

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