i am a service electrician i had a fire on a water heater but it did not start by electric or any other cumbustable. the burn marks are aroung a water pipe and the wall that burnt does not have any electric. the heater had no ground just 2 conductors in emt but it changed to 3/4" metal flex alum. this is my theory is that the water heater shorted and could not find a good ground so it traveled the water pipe but something cause the pipe to get red hot to start the fire.
strange fire
- Thread starter dave1976
- Start date
- Status
- Location
- Illinois
- Occupation
- retired electrician
Charlie,
You make a very good point. It is very difficult to have a pipe that contains water reach the ignition temperature of common building materials.
Don
You make a very good point. It is very difficult to have a pipe that contains water reach the ignition temperature of common building materials.
Don
- Location
- New Jersey
- Occupation
- Journeyman Electrician
First of all, if the feeder was in EMT with metallic flex than the unit was likely grounded. Having said that, I don't see how the current flowing on the pipe filled with water could start a fire.
yes but if the emt had loose fittings and the alum flex was long the electricity will take the path of least resistance. i have seen a picture of a copper water line glowing red. with water in it. there was no plumber the pipes were in a sheet rock wall fire start inside of the wall arson was ruled out and the marhall and electric inspector was dumbfounded
- Location
- Illinois
- Occupation
- retired electrician
Dave,
Don
That is not possible if the pipe still has water in it. On a closed piping system, the combination of the high pressure inside the pipe along with the weakening of the pipe as a result of the heat would cause the pipe to vent and the water would escape as steam. At that point you may be able to get the pipe to glow red, but that would assume that it is not connected to an active water supply. If it is connected to the an active water supply, the flowing water would keep the pipe below the temperature that is needed to make it glow red. It would also take a tremendous amount of current to make copper pipe glow red.
Don
Jim W in Tampa
Senior Member
- Location
- Tampa Florida
Check to see if the neutral for the service is still good.Perhaps the copper water line was acting as a return.Still puzzling is for it to loose water first in order to get this hot.On one of mike holts tapes (11 years ago) there was something about a duplex that was letting metal lath acting as return.It could take years for it to carbanize enough to flash .
the pipe from the hot water heater is gav. pipe. i know it will take alot to make it hot enough to catch fire but there is now other explaintion on how the fire started like i said the fire marshall and electric inspector was dumbfounded. and there was not any electric in that wall.
nbkelectric
Member
water heater
water heater
I had a lightning hit last month on here and the wire to the water heater ( two wire with no ground) had no visible damage, but the water heater internal wires were damaged. Possibly because the heater was sitting an a wet basement floor this was the closest thing to a ground. The copper water lines were not bonded and the water line to the well was replaced with plastic. Just a thought.bg
water heater
I had a lightning hit last month on here and the wire to the water heater ( two wire with no ground) had no visible damage, but the water heater internal wires were damaged. Possibly because the heater was sitting an a wet basement floor this was the closest thing to a ground. The copper water lines were not bonded and the water line to the well was replaced with plastic. Just a thought.bg
Jim W in Tampa
Senior Member
- Location
- Tampa Florida
From a guy that has 15 years of TV repair and 25 as electrician lightning follows nobodys laws.It can and has hit things isolated from any connections.Seen the hole it put thru a window and blow a bedroom to pieces, never ever try to figure out why.Just respect its abillities.
charlie tuna
Senior Member
- Location
- Florida
i agree ---- copper pipe with water inside will never glow red--- the temperatue of the pipe to turn it red would cause the water to flash to steam and would expand and blow the copper pipe out!!!
i have seen damages to the water heater caused by lightning --- for some reason the high voltage travels through and over many surfaces and ends up at the water heater --- must have something to due with a low impeadance path to ground???
i have seen damages to the water heater caused by lightning --- for some reason the high voltage travels through and over many surfaces and ends up at the water heater --- must have something to due with a low impeadance path to ground???
Jim W in Tampa
Senior Member
- Location
- Tampa Florida
I for one hope you post the outcome if they ever figure it out.Something is missing about this.
ramsy
Roger Ruhle dba NoFixNoPay
- Location
- LA basin, CA
- Occupation
- Service Electrician 2020 NEC
If the burn marks were caused by arcing from pipe to wall flashing/chicken wire, arcing is hot enough to do it. If arcing occured nearby, maybe high-arc frequencies caused skin-effect heating further along the pipe?
tallgirl
Senior Member
- Location
- Great White North
- Occupation
- Controls Systems firmware engineer
Although the water heater is pressurized the same as the water in the pipe, I don't think of public utility water as "high pressure", in the sense that the water would have to reach the critical temperature before there was enough pressure in the pipe to force water from the hot water heater back into the supply. Water boils at around 320F under 60psi pressure, and 60psi is more than I get from my utility. Once the water had boiled locally, the copper pipe would have been free to warm up rapidly as there would have been nothing left to absorb the heat. Since the copper is able to stand 60psi it wouldn't have ruptured and there would have been no reason for the water to flash since it would have been below the critical temperature (around 700F).
Another thing is that the mass of water in a 1/2" copper line from the W/H isn't all that much. Compared to the mass of water in the tank itself, heating the water in the pipe would be easy given enough time.
One test of this hypothesis is whether or not the fire started at a localized high point in the pipe, such as where it came out from the top of the W/H, went into the wall, then went back down into the floor. If vapor was forming it would have collected in the highest point local to the source of the vapor. If that's also a location that was being heated, eventually the vapor would have filled the pipe, the liquid would no longer have been there to absorb the heat, and the temperature would have spiked.
Another thing is that the mass of water in a 1/2" copper line from the W/H isn't all that much. Compared to the mass of water in the tank itself, heating the water in the pipe would be easy given enough time.
One test of this hypothesis is whether or not the fire started at a localized high point in the pipe, such as where it came out from the top of the W/H, went into the wall, then went back down into the floor. If vapor was forming it would have collected in the highest point local to the source of the vapor. If that's also a location that was being heated, eventually the vapor would have filled the pipe, the liquid would no longer have been there to absorb the heat, and the temperature would have spiked.
- Status