Thawing water pipes with a welder.

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GoldDigger

Moderator
Staff member
Location
Placerville, CA, USA
Occupation
Retired PV System Designer
I am listening to the OP's argument but logic behind this practice using a welder should be safe from the standpoint that only current can flow between the leads of the welder since the transformer line/load windings are isolated from each other.
If memory serves me right I think my welder instructions even show how to thaw metallic pipes with it.
Now if there is a defect in the welder I could see problems.
Anyone wish to elaborate on what actually occurred when there were fire damages caused by using a welder?
The main cause of damage when using a welder to thaw pipes is that there is no direct solid electrical continuity between the attachment points of the two welder clamps. (I will call them the tool clamp and the return clamp, since it just confuses things to call the return a ground clamp. :)

If, for example, the return clamp and the work clamp are on opposites sides of a dielectric union in the pipe, then the thawing current will flow through any combination of bonding jumpers that completes the circuit. And in the absence of proper bonding, along with some basic but common miswiring, you could even end up with the welding current flowing through a branch neutral instead. Or a bonding jumper or neutral with a poor connection.

End result is heating where it is not wanted and is not safe. The voltage by itself is not a high risk condition, but the voltage is an indication that high current is flowing on a path which has too high a resistance.
 

Sierrasparky

Senior Member
Location
USA
Occupation
Electrician ,contractor
Just because I feel that the NEC is not the place for such a code does not mean that nothing should be done to prevent use. Just not in the NEC.

Local and state ordinances yes for sure.


Building code no. .


Health and safety code Yes
 
NEC article 250.50 & 250.52 A 1 that "A metal underground water pipe in direct contact with the earth for 10 ft or more is a grounding electrode and must be bonded with other grounding electrodes".

OK, I get that. However, if an electrical charge is going to be applied to the metallic water pipe within that ten ft, then why use it as a grounding conductor if it can be hazardous? It's obvious we all know this practice can be a hazard, so why not prevent it. I think the most logical thing to do would be remove 250.52 (A) (1) from the code. That would solve the problem, would it not? Tell you what I'm going to do to protect my house. I'm going to remove the ground from my water pipe. I'm going to dig up my water pipe and replace the copper tubing with CTS plastic pipe. Then my house will be exempt from 250.52 (A) (1) and I won't ever have to worry about it again, but what about everyone else?

Most of the newer heating appliances and electronics today require 0v on ground to operate properly. I think this should be taken into consideration also. Start putting stray voltage on the ground and these appliances and electronics are going to burn out/up.
 
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Sierrasparky

Senior Member
Location
USA
Occupation
Electrician ,contractor
NEC article 250.50 & 250.52 A 1 that "A metal underground water pipe in direct contact with the earth for 10 ft or more is a grounding electrode and must be bonded with other grounding electrodes".

OK, I get that. However, if an electrical charge is going to be applied to the metallic water pipe within that ten ft, then why use it as a grounding conductor if it can be hazardous? It's obvious we all know this practice can be a hazard, so why not prevent it. I think the most logical thing to do would be remove 250.52 (A) (1) from the code. That would solve the problem, would it not? Tell you what I'm going to do to protect my house. I'm going to remove the ground from my water pipe. I'm going to dig up my water pipe and replace the copper tubing with CTS plastic pipe. Then my house will be exempt from 250.52 (A) (1) and I won't ever have to worry about it again, but what about everyone else?

Most of the newer heating appliances and electronics today require 0v on ground to operate properly. I think this should be taken into consideration also. Start putting stray voltage on the ground and these appliances and electronics are going to burn out/up.

You certainly can do that.
The intention of that code it bring everything to similar potential.
The code cannot always dictate nor prevent what some service technician might do.
What happened in your neighborhood should not be done that way. The power should be turned off and the ground removed. Tagged and locked. You know that will never happen.

Maybe contact the Local OSHA rep.
 

kwired

Electron manager
Location
NE Nebraska
The smart thing to do is to remove the grounding electrode conductor, isolate from the interior piping, but how do you know what the path is between the entrance to the house and that fire hydrant or curb stop? Curb stop maybe is a fairly direct path - but maybe there is a non metallic component or section of pipe somewhere between , or an unknown tap to another building - now you maybe have current flowing in places you are not aware of. Most of the time you are maybe pretty certain what is in the path or what parallel paths may be present, but at same time you really don't know if they are buried in the ground, those are the incidents that get you into trouble.

There is another thread about thawing ice in a raceway and suggested to use gas line antifreeze. would work for this as well when it comes to thawing the ice - but a big problem with water supply contamination.
 

Eddy Current

Senior Member
I am very aware that thawing water pipes with electrical current can be dangerous. Yesterday, in Long Lake, NY, I came home from work only to see the Town employees thawing a neighbor's water pipe with the old welder they have been using for many years. As I was outside, talking to my immediate neighbor, he informed me they were coming to his house next because his water had froze. Before I came into my own house, I went to my truck and grabbed my electrical tester. I proceeded to the basement and tested for voltage on the copper water pipe, with the ground still connected to the water pipe, there was 1.1 volts AC. I put one test lead directly on the water pipe and the other to the buss bar in the main circuit panel. When the welder shut down, the voltage dropped to .1 volts.

Then, it was time for them to connect to the house next door. Knowing they were closer, and that they use AC volts, but not knowing how exactly how many volts they use, I disconnected the ground cable to the water pipe. I tested for voltage on the water pipe, there was 0 volts. The Town employee dragged one cable and hooked it to the fire hydrant directly across the road from my house. I assume they connected the other cable to the water pipe in the house next door. They started the machine, but something was wrong, and they shut the machine down. I did not have enough time to test for voltage. They then came over to my curb stop, took the cap off and inserted the key. After he thought he had a good connection, he hooked the cable up to the key. They started the machine and the same thing, something was wrong, so they shut it down. I can only assume they were too far apart with the cable to get the proper amperage.

They ended up hooking the lead to a Curb Stop on the neighbors house on the opposite side of the house they were attempting to thaw. They started the machine and began to charge the water pipe with AC volts. I took a reading at my incoming water pipe. Again, one lead on the water pipe (ground wire disconnected) and the other to the main buss bar. Voltage was now reading 3.4 volts. The voltage dropped to 1.8 volts but would spike to 3.4 volts on occasion. I can only wonder what the voltage would have been had they connected to my curb stop.

One thing that really upset me was the fact that the Town employee did not notify us of what was going to happen, and I think they should have, especially if they were going to be hooked to my curb stop. There has been problems in the past, using this method to thaw water pipes. They have burnt out phone systems, receptacles and electronics in homes. Fortunately, they haven't caused a fire in someone's home, however, that is just a matter of time. I've seen that happen in surrounding Towns and they no longer thaw water pipes with electricity.

In Canada, thawing water pipes with electric is outlawed. I believe the NEC needs to step in and regulate or even outlaw this practice in the United States. I'm surprised they haven't stepped in on this practice, that I know of, yet. Thawing water pipes with electric is not safe, period! I don't care how good one is, or how long they have been doing it, there is always the potential of starting a fire in someone's house or a neighbor's house, plus the chance of electrical shock to those using this practice. Also, thawing with electricity will only work with metallic pipe, it will not work with any plastic pipe. Steam or Hot Water Jetter are the safest way to thaw buried water pipe.

I look forward to reading any and all comments to this thread.


Heat tape is outlawed in Canada?
 
I want to thank you all for your input and thoughts on this subject, that is why I came here with this. Thing is, there is a problem that needs to be corrected, and all your input will be used as argument to correct the problem. I will try to start on the local level, eventually moving up to the state level. I totally understand what you have all said, and I truly thank you. This is something I am not going to let go until it is resolved. I've seen and repaired way too many instances from this practice, I can not let it continue.

This past February, at 2 AM, -26F outdoor temperature, an elderly couple narrowly escaped injury when their house burnt, a total loss. The cause is believed to be electrical, however it is still under investigation. Earlier, the day before, the Town had thawed a water pipe across the road, coincidence, maybe; cause, very possible. If thawing the water pipe with electricity contributed to this tragedy and I can help prevent it from happening again, I'm going to do it :)
 

kwired

Electron manager
Location
NE Nebraska
Heat tape is outlawed in Canada?
I think the problem here is that the frost level in the ground has reached the point that it has frozen buried lines. Happens when you have a little more cold weather then usual or if finished grade above a line has maybe changed over the years and it is now a little on the shallow side.
 

ghostbuster

Senior Member
I want to thank you all for your input and thoughts on this subject, that is why I came here with this. Thing is, there is a problem that needs to be corrected, and all your input will be used as argument to correct the problem. I will try to start on the local level, eventually moving up to the state level. I totally understand what you have all said, and I truly thank you. This is something I am not going to let go until it is resolved. I've seen and repaired way too many instances from this practice, I can not let it continue.

This past February, at 2 AM, -26F outdoor temperature, an elderly couple narrowly escaped injury when their house burnt, a total loss. The cause is believed to be electrical, however it is still under investigation. Earlier, the day before, the Town had thawed a water pipe across the road, coincidence, maybe; cause, very possible. If thawing the water pipe with electricity contributed to this tragedy and I can help prevent it from happening again, I'm going to do it :)

Here is some info from a recent professional electrical investigation:


The Town of Sioux Lookout employees were unthawing a frozen waterline with an approved water thawing machine. As soon as the machine was connected the tenant in apartment 3 smelled smoke and the smoke detector went into alarm.



The breakers for the hot water tank, dryer, fridge, dishwasher and a lighting circuit tripped.



The investigation revealed that the water meters had not been removed prior to energizing the water pipe and that there was a rubber connection from the main water supply line to apartment 3 supply line.



Apartment 1 & 3 were connected to the thawing machine. The current traveled through the copper piping to the hot water tank, traveling along the hot water tank bonding conductor to the main service panel. From the main service panel along the neutral conductors and main service ground conductor of each apartment panel, and back to the thawing machine along the main water supply line of apartment # 1.



The high current generated by the thawing machine, flowing on the bond conductor of the NMSC caused considerable heat which melted into the exterior sheath as well as the insulated conductors contained in the cable assembly.
 
Here is some info from a recent professional electrical investigation:


The Town of Sioux Lookout employees were unthawing a frozen waterline with an approved water thawing machine. As soon as the machine was connected the tenant in apartment 3 smelled smoke and the smoke detector went into alarm.



The breakers for the hot water tank, dryer, fridge, dishwasher and a lighting circuit tripped.



The investigation revealed that the water meters had not been removed prior to energizing the water pipe and that there was a rubber connection from the main water supply line to apartment 3 supply line.



Apartment 1 & 3 were connected to the thawing machine. The current traveled through the copper piping to the hot water tank, traveling along the hot water tank bonding conductor to the main service panel. From the main service panel along the neutral conductors and main service ground conductor of each apartment panel, and back to the thawing machine along the main water supply line of apartment # 1.



The high current generated by the thawing machine, flowing on the bond conductor of the NMSC caused considerable heat which melted into the exterior sheath as well as the insulated conductors contained in the cable assembly.

Interesting, thank you!
 
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