- Location
- Bremerton, Washington
- Occupation
- Master Electrician
Last week there was a post stating that a plumber was complaining that grounding electrical services to water pipes caused corrosion. I replied that the American Water Works Association (AWWA) has a research report "Effects of electrical grounding on pipe integrity and shock hazard" and that this study show no effect on pipe corrosion from grounding.
I reviewed the study, my post was somewhat incorrect. The AWWA studied more than 100 homes and measured the AC and DC current on water pipes.
Note the following
1. AC current causes about 1% of the corrosion of DC
2. DC current can be towards the house or away from the house, if away it is causing corrsion of the metal pipe.
3. The DC is variable from sources such as dryers and electric drills
4. The amount of corrosion is greatly dependant on the soil resistivity, soil pH and chemicals present in the soil
5. A non metallic water service line will stop current and corrosion. Many water utilites install insulating jumpers at the water meter.
6. About 1 water meter repair person recieves a serious electric shock a day in the US- most likely due to open neutrals. This can be stopped by a insulating jumpers at the water meter.
7. Some utilities can not use a insulating jumpers at the water meter as they use electric pipe thawing in the winter.
The research report is very detailed and well written, 215 pages long. Its no longer in print, however.
[ August 23, 2005, 03:05 PM: Message edited by: tom baker ]
I reviewed the study, my post was somewhat incorrect. The AWWA studied more than 100 homes and measured the AC and DC current on water pipes.
Note the following
1. AC current causes about 1% of the corrosion of DC
2. DC current can be towards the house or away from the house, if away it is causing corrsion of the metal pipe.
3. The DC is variable from sources such as dryers and electric drills
4. The amount of corrosion is greatly dependant on the soil resistivity, soil pH and chemicals present in the soil
5. A non metallic water service line will stop current and corrosion. Many water utilites install insulating jumpers at the water meter.
6. About 1 water meter repair person recieves a serious electric shock a day in the US- most likely due to open neutrals. This can be stopped by a insulating jumpers at the water meter.
7. Some utilities can not use a insulating jumpers at the water meter as they use electric pipe thawing in the winter.
The research report is very detailed and well written, 215 pages long. Its no longer in print, however.
[ August 23, 2005, 03:05 PM: Message edited by: tom baker ]
