House with potential fire issue

[dronai]

Thanks

Thanks

The Grounding Electrode System has little to do with clearing ground faults or short circuits. Please watch this link, slides 10 -68 are critical. http://www.tirebiter.net/downloads/ludecke.html

Watched it ! very good information there. I am very familiar with most of the info with exception to that it takes 5 to 6 times the rating of the cb to open, and that I clearly forgot to check to see if the main service was indeed bonded !!!! I took that for granted :happyno: who installs a service without bonding !!! I noted the ground rod, and GEC, and connection to the plumbing, but I didn't check to see if someone ran the GEC to the service also, and bonded the GEC to the neutral bus !!!!!! This would explain a lot. The "Forensic Expert" missed it too. He told me to run a new ground back to the service from wherever that wire was connected, and bond the plumbing where it was cut out. Thanks guys !! Feel better about how to tackle this now.

 

[GoldDigger]

Watched it ! very good information there. I am very familiar with most of the info with exception to that it takes 5 to 6 times the rating of the cb to open, and that I clearly forgot to check to see if the main service was indeed bonded !!!! I took that for granted :happyno: who installs a service without bonding !!! I noted the ground rod, and GEC, and connection to the plumbing, but I didn't check to see if someone ran the GEC to the service also, and bonded the GEC to the neutral bus !!!!!! This would explain a lot. The "Forensic Expert" missed it too. He told me to run a new ground back to the service from wherever that wire was connected, and bond the plumbing where it was cut out. Thanks guys !! Feel better about how to tackle this now.

You also need to verify that there really is a neutral wire for the circuit in question. There has to be a reason that the current was flowing in the "ground" wire rather than the neutral. If the ground and grounded wires have roughly equal resistance, the current will divide nicely and there will not be enough voltage across a bad (high resistance) connection in one path to generate any heat.
I would look for this being a bootleg neutral rather than a bootleg ground. Such as maybe creating a neutral for a receptacle while taking one hot from a 240V range or water heater circuit that did not have a neutral in the first place. And maybe had a high current breaker or fuse, for that matter.

 

[kwired]

Your forensic expert may have concluded a bad connection was the source of the fire, what he did not determine was why there was current flowing there in the first place.

And ground rods are not for clearing faults. If you had a rod with 10 ohms resistance (pretty good for a ground rod) and applied 120 volts you only get 10 amps of current. A 15 or 20 amp breaker should hold at this level indefinitely so no fault clearing is going to happen. Grounding electrodes are nothing more than an earth reference point and a place for lightning surges to find a path to earth.

 

[templdl]

Your forensic expert may have concluded a bad connection was the source of the fire, what he did not determine was why there was current flowing there in the first place.

And ground rods are not for clearing faults. If you had a rod with 10 ohms resistance (pretty good for a ground rod) and applied 120 volts you only get 10 amps of current. A 15 or 20 amp breaker should hold at this level indefinitely so no fault clearing is going to happen. Grounding electrodes are nothing more than an earth reference point and a place for lightning surges to find a path to earth.

I agree. I asked him to draw out the point of service which I think will identify the grounding and neutral issue. That seems to be the source of the current that caused the fire.

 

[dronai]

Your forensic expert may have concluded a bad connection was the source of the fire, what he did not determine was why there was current flowing there in the first place.
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He said, The loose clamp, with a corroded surface on the pipe under the clamp, and a difference in potential on that plumbing pipe, and the rest of the system is what caused the arcing.

 

[ggunn]

He said, The loose clamp, with a corroded surface on the pipe under the clamp, and a difference in potential on that plumbing pipe, and the rest of the system is what caused the arcing.

If it were just an auxiliary ground attached to a correctly grounded system with a correctly bonded neutral, there would not have been that difference in potential with enough current behind it to cause the arc. Cleaning and tightening the clamp doesn't solve anything; it's a symptom, not the root cause of the problem.

 

[templdl]

He said, The loose clamp, with a corroded surface on the pipe under the clamp, and a difference in potential on that plumbing pipe, and the rest of the system is what caused the arcing.

Regardless, there shouldn't have been any appreciable current if any at that point. I would conclude the what was being scene was neutsl current which was supposed to be present at that point. The failure was a symptom of a defectce service entrance to begin with.

 

[GoldDigger]

Regardless, there shouldn't have been any appreciable current if any at that point. I would conclude the what was being scene was neutsl current which was supposed to be present at that point. The failure was a symptom of a defectce service entrance to begin with.

A problem at the service entrance (which POCO did not find on their side of the service point) would cause the neutral voltage to vary with load. It would not and could not, by itself, cause current to flow through an EGC or GEC rather than through an un-grounded neutral.

The one thing that has to be explained is where the current in the arc was originating. A simple stray voltage will not start a fire.

 

[templdl]

A problem at the service entrance (which POCO did not find on their side of the service point) would cause the neutral voltage to vary with load. It would not and could not, by itself, cause current to flow through an EGC or GEC rather than through an un-grounded neutral.

The one thing that has to be explained is where the current in the arc was originating. A simple stray voltage will not start a fire.

I agree with the stray voltage point as that normally would be insignificant. It certainly appears as if it's a neutral issue. Thats 's why I would explore the SE panel and verify that the neutral it bonded only to the ground at yh as t point and that the neutral current isn't taking as anotpat path which appears to have happened resulting in the fire.

 

[dronai]

Update

Update

The Main is bonded to the plumbing system under the house. Crawled and looked at the connection. The ground rod is also ran to the plumbing system, but I couldn't access the connection point. I found the bootleg neutral in a receptacle box that had a new 14-2 romex, using only the black wire and the bootleg neutral. Ran a continuity test, and it rang out on the suspect wire. Interesting is Allstate insurance is going after the plumber for cutting the pipe, and not installing a jumper wire ??? I wouldn't think a plumber would even know to do this.

 

[templdl]

The Main is bonded to the plumbing system under the house. Crawled and looked at the connection. The ground rod is also ran to the plumbing system, but I couldn't access the connection point. I found the bootleg neutral in a receptacle box that had a new 14-2 romex, using only the black wire and the bootleg neutral. Ran a continuity test, and it rang out on the suspect wire. Interesting is Allstate insurance is going after the plumber for cutting the pipe, and not installing a jumper wire ??? I wouldn't think a plumber would even know to do this.

Maybe that's an issue by why is the the magnitude of objectionable current there? If the bonding to the water pipe was insufficient to carry that current heating to a point causing a fire if the bond was sufficient then where is the current flowing to after that? You may have hit on something if in fact the neutral has been bonded to the ground at more than one point, a point in addition that that of the SE panel. If so neutral current may have been turned loose on the EGC.

 

[SG-1]

Dronai, how much current is flowing on the pipe ?

Is the current present between the GEC bond & the water meter ? Or can the current be measured at the water meter ?

Is the current only present on the water pipe inside the GEC bond ?

If the current was present when the plumber cut the pipe it is a wonder he was not killed or injured.

Just a thought, this could be a ground fault at the hot water tank, if no Equipment Grounding Conductor is present there. An element has gone bad & current is flowing through the pipe onto the GEC & back to the panel.

 

[kwired]

The Main is bonded to the plumbing system under the house. Crawled and looked at the connection. The ground rod is also ran to the plumbing system, but I couldn't access the connection point. I found the bootleg neutral in a receptacle box that had a new 14-2 romex, using only the black wire and the bootleg neutral. Ran a continuity test, and it rang out on the suspect wire. Interesting is Allstate insurance is going after the plumber for cutting the pipe, and not installing a jumper wire ??? I wouldn't think a plumber would even know to do this.

When you mention the "bootleg" neutral, do you mean the neutral for the receptacle in question is dependent on the water pipe as part of the path? That would answer the question of why the current on the loose clamp. Why isn't insurance going after whoever installed the bootleg neutral instead of the plumber? There is likely several NEC violations that could be cited in this install, and maybe very few plumbing code issues - at least that would directly cause the fire.

 

[ggunn]

Interesting is Allstate insurance is going after the plumber for cutting the pipe, and not installing a jumper wire ??? I wouldn't think a plumber would even know to do this.

That's just stupid. He's a plumber, not an electrician. The problem isn't the pipe, it's the current being routed to it on that ground wire. Like someone else said, the plumber is lucky he wasn't hurt or even killed when he started messing with that stuff.

Is that "bootleg neutral" connected to the suspect wire and ONLY the suspect wire, maybe?

 

[templdl]

That's just stupid. He's a plumber, not an electrician. The problem isn't the pipe, it's the current being routed to it on that ground wire. Like someone else said, the plumber is lucky he wasn't hurt or even killed when he started messing with that stuff.

Is that "bootleg neutral" connected to the suspect wire and ONLY the suspect wire, maybe?

Yes, the plumber was very lucky. It is a symptom of a very serious problem.

 

[dronai]

Maybe that's an issue by why is the the magnitude of objectionable current there? If the bonding to the water pipe was insufficient to carry that current heating to a point causing a fire if the bond was sufficient then where is the current flowing to after that? You may have hit on something if in fact the neutral has been bonded to the ground at more than one point, a point in addition that that of the SE panel. If so neutral current may have been turned loose on the EGC.

There is no EGC in most of that house ! This is an old 2 wire system.

Dronai, how much current is flowing on the pipe ?

Is the current present between the GEC bond & the water meter ? Or can the current be measured at the water meter ?

Is the current only present on the water pipe inside the GEC bond ?

If the current was present when the plumber cut the pipe it is a wonder he was not killed or injured.

Just a thought, this could be a ground fault at the hot water tank, if no Equipment Grounding Conductor is present there. An element has gone bad & current is flowing through the pipe onto the GEC & back to the panel.

This was a unoccupied vacation house being upgraded plumbing wise to rent for a month. When the plumber cut the pipe, the only load would have been his, and another trade that was sharing the same circuit. The fire didn't start until about a week later. The forensic PE told the home owner, that fire could have been smoldering that whole week. This is not a water heater issue, this is a return path on a bootleg neutral using the pipes as a conductor being cut. IMO, I believe there was still enough of a high resistance path to allow the circuit to continue, but causing heat at the loose contact point.

When you mention the "bootleg" neutral, do you mean the neutral for the receptacle in question is dependent on the water pipe as part of the path? That would answer the question of why the current on the loose clamp. Why isn't insurance going after whoever installed the bootleg neutral instead of the plumber? There is likely several NEC violations that could be cited in this install, and maybe very few plumbing code issues - at least that would directly cause the fire.

Yes on your first question. This house is a two wire system 1927 home. The person that wired it is likely not around any more. The blame is also being equal, but it sounds like Allstate is going after what's available.

That's just stupid. He's a plumber, not an electrician. The problem isn't the pipe, it's the current being routed to it on that ground wire. Like someone else said, the plumber is lucky he wasn't hurt or even killed when he started messing with that stuff.
Is that "bootleg neutral" connected to the suspect wire and ONLY the suspect wire, maybe?

AGREED !! IMO, I think most of these old homes used to use the galvanized plumbing system as their grounding grid. This is a two wire knob and tube system. Only portions of the kitchen have been rewired with newer nm with a ground wire landed in the panel." Is there more than one neutral connection point to the plumbing pipes"
How would we know this ? The bad news is, if someone attached the old cloth wiring using the plumbing as a return path in another location, this has been cut now, and was located in an inaccessible area under the hot mopped shower ! They covered this up before a jumper wire was installed.

 

[dronai]

From my previous post "The bad news is, if someone attached the old cloth wiring using the plumbing as a return path in another location, this has been cut now, and was located in an inaccessible area under the hot mopped shower ! They covered this up before a jumper wire was installed" Edit: I guess for the bootleg neutrals that is not bad news ! It will disable them and locate other areas. Regardless, a complete rewire is going to be scheduled a few months down the road.

 

[ggunn]

There is no EGC in most of that house ! This is an old 2 wire system.

This was a unoccupied vacation house being upgraded plumbing wise to rent for a month. When the plumber cut the pipe, the only load would have been his, and another trade that was sharing the same circuit. The fire didn't start until about a week later. The forensic PE told the home owner, that fire could have been smoldering that whole week. This is not a water heater issue, this is a return path on a bootleg neutral using the pipes as a conductor being cut. IMO, I believe there was still enough of a high resistance path to allow the circuit to continue, but causing heat at the loose contact point.

Yes on your first question. This house is a two wire system 1927 home. The person that wired it is likely not around any more. The blame is also being equal, but it sounds like Allstate is going after what's available.

AGREED !! IMO, I think most of these old homes used to use the galvanized plumbing system as their grounding grid. This is a two wire knob and tube system. Only portions of the kitchen have been rewired with newer nm with a ground wire landed in the panel." Is there more than one neutral connection point to the plumbing pipes"
How would we know this ? The bad news is, if someone attached the old cloth wiring using the plumbing as a return path in another location, this has been cut now, and was located in an inaccessible area under the hot mopped shower ! They covered this up before a jumper wire was installed.

It seems to me that he underlying problem may be the partial rewiring jobs where the wiring of the whole house wasn't taken into account. "What happens if I cut this wire? Hey, everything still works, so it must be OK."

 

[kwired]

There is no EGC in most of that house ! This is an old 2 wire system.

This was a unoccupied vacation house being upgraded plumbing wise to rent for a month. When the plumber cut the pipe, the only load would have been his, and another trade that was sharing the same circuit. The fire didn't start until about a week later. The forensic PE told the home owner, that fire could have been smoldering that whole week. This is not a water heater issue, this is a return path on a bootleg neutral using the pipes as a conductor being cut. IMO, I believe there was still enough of a high resistance path to allow the circuit to continue, but causing heat at the loose contact point.

Yes on your first question. This house is a two wire system 1927 home. The person that wired it is likely not around any more. The blame is also being equal, but it sounds like Allstate is going after what's available.

AGREED !! IMO, I think most of these old homes used to use the galvanized plumbing system as their grounding grid. This is a two wire knob and tube system. Only portions of the kitchen have been rewired with newer nm with a ground wire landed in the panel." Is there more than one neutral connection point to the plumbing pipes"
How would we know this ? The bad news is, if someone attached the old cloth wiring using the plumbing as a return path in another location, this has been cut now, and was located in an inaccessible area under the hot mopped shower ! They covered this up before a jumper wire was installed.

True the metallic plumbing system was allowed to be used as part of the grounding electrode system and it was permitted to pick up equipment grounding conductors off the piping system but it was never allowed to use the plumbing as a current carrying (neutral) conductor AFAIK, and that is what it appears may have been the case here.

 

[GoldDigger]

From my previous post "The bad news is, if someone attached the old cloth wiring using the plumbing as a return path in another location, this has been cut now, and was located in an inaccessible area under the hot mopped shower ! They covered this up before a jumper wire was installed" Edit: I guess for the bootleg neutrals that is not bad news ! It will disable them and locate other areas. Regardless, a complete rewire is going to be scheduled a few months down the road.

Regarding the cut pipe and the plumber's responsibility: If the cut pipe was part of the bootleg neutral path, then everything plugged into that circuit should have immediately stopped operating. Cutting the pipe could not increase the current through the loose clamp, which was pre-existing before the pipe was cut.
Most likely the cause was the various trades putting a higher current load on that circuit than it had been exposed to for a long time. That may also have caused a poor connection to heat up and become an arcing or glowing connection instead, after some heating/cooling cycles.