My facility recently replaced a hot water heater. This is a 3 phase 440 Volt heater.
The original water supply to this heater was galvenized pipe. It has been replaced with plastic. I am of the opinion that it would be a lot safer to pull in a ground wire, rather than rely on conduit for grounding. This conduit has been there for over 30 years and we have had several roof leaks with conduit getting wet and corroded. What would be your recommendations for this?

Welcome to ECN.
Our 'standard' practice is to "pull a ground".

Also, don't forget to 'jump' the metalic hot and cold water lines, as you may have 'lost' the grd bond with the replacement htr.

John

While this is never a bad thing to do there is no specific requirement in the NEC to do so.

The metal water piping systems are required to be bonded however there is no reason that must happen at the water heater or that a bonding conductor must be installed.

The hot and cold water pipes are very likely to already be bonded together at tub and shower valves, laundry valves, mixing valves at the boiler etc.

If we say those are not reliable connections we might as well put a bonding jumper around every soldered connection.

For what it's worth here is the 2002 Handbook commentary.


Hey John I am not picking on you here, this is just a pet peeve of mine when I see inspectors say the hot and cold must be bonded at the water heater.


Bob

Thanks John & Iwire, just a point of info. This heater is for shower facilities. Original was installed in the sixties at which time there were no requirements for the hot & cold water lines to be bonded together. In this case I think it is an excellent idea. We now have plastic supplying the heater and galvenized running to the shower and lavatory facilities. John, when you say pulling a ground is standard practice in your area, are you referring to replacement of existing equipment, new equipment or both?

Bob,

I agree with you that the hot and cold water must be bonded together but not at the water heater. If I was inspecting a job and I don't see the jumper wire at the water heater, I would try to look at a boiler or washing machine to see if there is a connection between the two. However for the $5-$7 dollers worth of parts for the bonding wire and clamps, most guys just throw it on. Also if the bonding jumper isn't at the water heater and it is bonded elsewhere, sometimes it is hard to find out where it is bonded. Some AHJ's might not take the extra time to try and find out where it is bonded.