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Tanklets > Grounding a Water Heater

Q: I was curious if the tank in my new,uninstalled American water heater was isolated electrically from the gas connection. It is not, which means that the tank will always be at ground potential even if the water lines are connected with insulated dielectrics. The question is whether, in an ideal world, there is any advantage to have the water tank "float" electrically since in a real world this seems to be impossible.

A: The answer is that the gas line is conductive through to the tank. I'd consider grounding/bonding to the gas line (if it's steel) to prevent any stray current from wanting to visit your water heater. Have a look at my answer at the end of your post "dielectric unions". It may cover this question in part. I'd think of the bits of equipment by their intended use. Dielectrics are to prevent galvanic corrosion. Grounding/bonding is to prevent/control stray currents. They do wind up with some functional overlap, affecting each other. But, both correctly installed will give you a good system -- Larry

Q1: Can I infer that it would a good idea to run the same 6 gauge copper jumper wire between the hot and cold lines and connecting it to the steel gas supply pipe?

A1: Hello and yes. I'm not sure what code says for certain regarding bonding wire size, but a little overkill now and then is perfectly OK. This bonding/grounding thing does seem to be a source of confusion: https://www.mikeholt.com/mojonewsarchive/GB-HTML/HTML/Grounding-vs-Bonding~20040121.htm -- Larry (7/28/10)

Q: We just installed a new water heater and have the same problem that we've had with the last two. Upon first draw the hot water runs brown. We have had two tanks fail due to this problem and now the newest one is headed in that direction. We've had the water company and water softener company out and those systems are ok.

In the second heater we changed to bi-metal unions but that made no difference and we replaced the heater after only a year of operation (the anode rod was fine). The newest tank is only 3 weeks old and already the water is running brown. If we pull water from the bottom of the tank it is light brown. All of the plumbing in the house is copper. Can anyone help with this extremely frustrating problem? We are absolutely stumped as is our plumber. Thanks!

A: Hello: Two things come to mind. Stray current corrosion could be the culprit. If anything was improperly grounded to hot piping and current leaked to ground, it would have to pass through the heater. This could easily damage a heater quickly. If any grounds went to the house piping and the main line serving the house were replaced with plastic pipe, you would have a poor ground path which could cause trouble.

Having an electrician out to check the grounding system and to install a 6 gauge copper jumper from hot to cold over the water heater couldn't hurt. This would give leaking current a place to go that would avoid the heater. Of course, any source of current needs to be found and fixed. Water meter installers often jumper across a meter they are working on as some such technicians have been electrocuted by stray currents.

The other thought is about the softener. If any resin from the unit got into the piping and tank, it possibly could cause the discoloration you see. Over softening the water could cause trouble too. You should leave 60 to 120 ppm (roughly 3-6 grains) of hardness in the water, or it can get aggressive towards the poor plumbing :? One last thing to look at is the water quality. Your supplier should issue a report yearly.-- Larry (1/26/08)