Grounding Electrode System Installation.

[Sherman]

I have a temporary portable steel shower unit with 10 showers and a hot water heater, 208 volt, 3 wire in the corner of the unit. The shower unit is fed from an "I" line MDP, which is fed by a generator with a bonded neutral. The panel has a driven ground rod as an equipment ground.

I am being told to run a #2 ground wire from the hot water heater to a separate ground rod for that hot water heater. I feel this is a code violation. Correct me if I am wrong.

 

[augie47]

Is there any grounding means (conduit or conductor) between the panel and the water heater ?

 

[Smart $]

I have a temporary portable steel shower unit with 10 showers and a hot water heater, 208 volt, 3 wire in the corner of the unit. The shower unit is fed from an "I" line MDP, which is fed by a generator with a bonded neutral. The panel has a driven ground rod as an equipment ground.

I am being told to run a #2 ground wire from the hot water heater to a separate ground rod for that hot water heater. I feel this is a code violation. Correct me if I am wrong.

A ground rod is a grounding electrode. It does not serve any equipment ground purpose.

The grounding electrode conductor that is the sole connection to a ground rod is not required to be larger than #6 copper but cannot be exposed to damage. Many run #4 to avoid having to put #6 in conduit.

A ground rod for the water heater is not required... but also not prohibited.

However, your system requires at least two grounding electrodes... and installing a ground rod connected to the water heater does not qualify as the second.

 

[Sherman]

There are two ground rods at the MDP and there is a PVC conduit from MDP to the hot water heater. I was just not sure if it was necessary for a third ground rod driven for the hot water heater. I would think that that would cause a difference in potential for grounding.

 

[John120/240]

There are two ground rods at the MDP and there is a PVC conduit from MDP to the hot water heater. I was just not sure if it was necessary for a third ground rod driven for the hot water heater. I would think that that would cause a difference in potential for grounding.

Your water is grounded by the EGC that is run with the circuit conductors. An additional

ground rod is not required but not prohibited.

 

[suemarkp]

I wonder if they are asking you to bond the water piping system? Is it metal pipe? Is that pipe bonded with a conductor sized per 250.66 back to the MDP or ground electrode system? A lone ground rod for the heater makes no sense to me.

 

[kwired]

Regardless of codes, my main concern here is if there is potential contact by the users between earth and potentially elevated voltage on the EGC? Since this is a shower, you will have people barefooted with wet surfaces and more vulnerable to lower voltage potentials than usual. Even though NEC may not require it, a look into some equipotential plane or at least an isolation barrier of some type at the entry or any other point of potential contact between earth and the metal frame by users should be considered. Voltage drop on service grounded conductor can be enough to have a voltage between EGC and earth even though nothing was done wrong.

 

[augie47]

You mention a PVC conduit to your water heater... is there an equipment grounding conductor run with that conduit ?
As Smart$ noted in Post 3, you need an equipment grounding conductor.
If you have a metallic water piping system it should be bonded to the service (or service grounding electrodes).
The ground rod at the shower is optional. Might not be a bad idea as kwired pointed out, but as an electrical circuit grounding means it's useless.