Testing Wire from Fire

[bonding jumper]

I have an apartment complex, the branch circuit wiring is done in bx and risers in conduits. Within the last year, the building electrical was renovated and replaced with new. In the last month, there was a fire in a few apartments affecting one riser.
My question is, is there a test to determine how the buildings wiring was effected by this fire? Is there a way to determine how the heat from the fire could have effected the wiring? If the wiring is in bx its hard to see what might have happened to the insulation inside the bx sheath.

How is this typically determined? Thanks any info is greatly appreciated.

[ July 15, 2003, 12:16 PM: Message edited by: bonding jumper ]

 

[bennie]

Re: Testing Wire from Fire

If in doubt, rip it out

 

[bonding jumper]

Re: Testing Wire from Fire

Would it be feasable to measure resistances of the wire with a meter and then do a calculation with legnth and size and see if it matches what is should be from the factory? I think I have a formula for that somewhere's in one of my books from college. Would the resistance show damage from fire? Is there a test for insulation condition? Maybe a continuity test from the conductor to the shield of the bx?

[ July 15, 2003, 01:08 PM: Message edited by: bonding jumper ]

 

[bennie]

Re: Testing Wire from Fire

The resistance will not necessarily change. The insulation is the concern.

A megger will tell you if it is holding at the time of test. It can then immediately fail.

There is no test available to assure the integrity of the wiring. I would not gamble with this issue.

Have anyone who insists on the wiring remaining, to sign off on the liability. Remember the collapse of the porch recently.

 

[bonding jumper]

Re: Testing Wire from Fire

Well, I don't want to instruct this building owner to have an unsafe building, I just want to know what to replace and what not to replace. Is there a type of Underwriters Labratory Testing or Electrical Engineers(not me) that can do some testing and analysis on how much life the wires have left? Does this exist? Thanks.

 

[bennie]

Re: Testing Wire from Fire

You indicate this is an apartment complex. There must be adults, children, and babies. Is the money worth it?

Insist on replacing all wiring that has been subjected to heat, or smoke. Smoke often contains carbon.

I don't think there is a testing lab person, with any ethics, that would sign off on this project.

If the owner balks, walk.

 

[charlie]

Re: Testing Wire from Fire

Is there a type of Underwriters Labratory Testing or Electrical Engineers(not me) that can do some testing and analysis on how much life the wires have left? Does this exist?

No, see Bennie's post of July 15, 2003 01:11 PM.

[ July 15, 2003, 03:35 PM: Message edited by: charlie ]

 

[flightline]

Re: Testing Wire from Fire

Bennie's post says it most eloquently. If you are a professional, you have a responsibiliy that cannot be shirked. It is two-fold. First, as Bennie has said, to the persons that may inhabit the structure at any time, and to yourself, or your business; a fiduciary one. You don't want to expose yourself to any untoward legal exposure. While yes, you must do business and generate revenue, it must do so in a manner that tries to keep you IN business.

You might try to speak to the insurer of the apartment complex, and let them state, in writing, what they want to see. They will be the first ones to be sued and then thrid party you in the terrible event something were to happen.

[ July 15, 2003, 04:29 PM: Message edited by: flightline ]

 

[sjaniga]

Re: Testing Wire from Fire

BJ,
We do a fair amount of fire repairs, first thing we do is a walk-through with the fire chief, he can tell were the fire started, what caused it, where the heat was. He then will determine what the safe distance, or what needs to be replaced is, we go from there talking with the customer. We have never had anything fail yet, knock on wood . If you have to put something in writing, use a lawyer to write it, as to keep your liability to only what you repaired.

 

[bonding jumper]

Re: Testing Wire from Fire

Thanks a lot guys, thats a big help. I want to do Instruct the owner to do the right thing here but on the same note, protect him from abuse. Thanks.

 

[brian john]

Re: Testing Wire from Fire

There is a simple test tahn can be made to determine the thwe usability of the wiring. A megger test/high potential test/over potential test. This is done all the time and is a resposible method to avoid just random rip tear and replace. NEAT test specs spell out the voltage to be applied and the duration of the test. It should be performed by a person fimilar with the test proceedure.

 

[david]

Re: Testing Wire from Fire

?Testing Wire from Fire?


?If in doubt, rip it out?


I think only answer that rhyme should be considered in this post

 

[brian john]

Re: Testing Wire from Fire

There is a test proceedure for almost every electrical situation. While common sense does fall into what is good and what is bad in the words of bennie why waste precious resources.

IMHO to randomnly replace cable that might be good and then maybe miss a piece that is bad is doing a dis-service to you yourself and your customer.

 

[jason]

Re: Testing Wire from Fire

Before I spent the money on test equipment and the labor to test it, I'd just replace. I'm sure that would be much cheaper.

 

[bennie]

Re: Testing Wire from Fire

Of course humans are our most precious resource.

My "Johnnie Cochran" response, was an educated guess, the wiring method is BX, this dates the age of the wiring.

Even with no fire, this apartment and the others are reaching their life expectancy.

I would not hesitate to remove anything that has been further degraded by the heat.

 

[brian john]

Re: Testing Wire from Fire

If one does any service work and don't own a Megger they should, if anyone energizes switchgear (in particular 480/277 VAC) and doesn't own a Megger get one, work on bus duct a must, repair under ground cable a must. Do electric work well I would not do work without one.

Meggers (high potential testers ect.) cost at the low end 300-400 dollars, IMHO if you’re doing any electrical trouble shooting ( involving tripped breakers, ground fault systems, motors, cabled, switchgear, feeders ect) and do not own a Megger you should retire. This is how electricians get hurt, blown up, burnt and damage customer equipment beyond repair.

I may be the lone voice on this but I shocked at the lack of understanding of this issue.

 

[jxofaltrds]

Re: Testing Wire from Fire

My last fire damage job. The heat was so intense that it melted the blinds in the house next door.

How could someone know how hot the fire was in any given example?

I would do as previously stated. Remove all wiring.

Mike P.

 

[pierre]

Re: Testing Wire from Fire

The original question says the wiring is 1 year old or less. Randomly replacing wire will make people think electricians are 'thieves'. I have been involved with fire jobs and it is generally not easy to deal with all the emotions set off in people by the fire, and then the decisions they have to make afterwords.
The obvious damage areas I would rip out, maybe even stretch that 'zone'. Then either hire someone or if you know how megger the other wiring that is suspect. One thing to remember is the conductor acts as a heat sink and the heat of the fire can travel a long way and not show any signs of damage to the outside of the cable or conduit.
Sometimes due to the nature of the fire damage, it may be more 'cost effective' to rip it out than do all the testing as has been mentioned, so the decision should be YOUR DECISION.
If the management does not let that decision be your decision, let them hire another EC.
Good Luck

Pierre

 

[brian john]

Re: Testing Wire from Fire

Mike:


Each job must be looked at thoroughly, obvious damaged cable MUST be replaced. BUT I GURANTEE, that I can tell more with my test equipment than you can with your approach. Cable that you might think was good may be bad and vice a versa.

I don't need to know how hot it was, don't care. I’ll tell you if it is good or bad.

My point is there are alternatives to randomly replacing all the wire. If you’re not familiar with the test or the procedures in testing cables please take to time to educate yourself. You are doing yourself and your customers an injustice.

 

[bennie]

Re: Testing Wire from Fire

A megger can give many false positives in the testing of insulation.

I have seen bare copper, from fire damage, read very high, due to not making contact with a grounded surface at the particular time. Air is a good insulator, but not in my conduit.

I required an insulation test, on cable, immediately after the pull is completed. The reason is the wire lube is still wet and any break in the insulation will show up in the test.
When tested the next day the cable will show clear, the flaw is undetected.

NM cable can be bare and still test as ok.

Please do not instruct others to use a megger to test wire after a fire, as the only deciding factor.

[ July 17, 2003, 10:40 AM: Message edited by: bennie ]