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Old 03-05-2012, 02:35 PM   #1
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Adding ground to electric water heater


Greetings all - I recently replaced my electric water heater and have a question about adding a ground connection.

The house was built before grounded connections were common. The old water heater could arguably have been grounded via the metal conduit, but I wasn't very confident about that connection.

Conveniently, my electrical service was replaced a few years ago, and in the process the electrician installed a ground rod and ran a fat (#4?) copper line to the cold water pipe, located just above the water heater.

So I figured it would be safer to connect the new water heater's ground screw directly to this new ground system rather than rely on the dubious conduit ground. I did so with a scrap piece of insulated solid-core copper wire I had laying around.

So my question is... is this code compliant(or at least compliant with the spirit if not the letter of code)?

If not, is it at least safer than what I had before?

Thanks for any input.

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Old 03-05-2012, 02:41 PM   #2
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Adding ground to electric water heater


If you had metallic conduit continuous to the panel this was your ground. You could also install a green #10 in the conduit.

The #4 bare is a bond conductor and is not for grounding.

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Old 03-05-2012, 02:51 PM   #3
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Adding ground to electric water heater


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Originally Posted by Jim Port View Post
If you had metallic conduit continuous to the panel this was your ground. You could also install a green #10 in the conduit.

The #4 bare is a bond conductor and is not for grounding.
Thanks for the quick reply!

The conduit is (probably, much of it is hidden by drywall) continuous to the panel, however it didn't seem like the joints were particularly tight.

My followup question(and I'm just trying to understand, not argue) is "why" using the bond conductor is not allowed? Isn't its purpose to allow for devices that were grounded to the cold water pipe to continue to be grounded in the event that the cold water pipe's connection to earth is interrupted by non-conducting pipe? Or is there another purpose?

Letter of the law aside, isn't a solid copper connection to a ground rod "safer" than a flaky conduit connection to the panel?

Thanks again.
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Old 03-05-2012, 03:21 PM   #4
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Adding ground to electric water heater


If the conduit is metal and runs continuous to the panel then that can be your ground. If you are unsure about anything posting pictures can be a big help to the people trying to help you.
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Old 03-05-2012, 05:06 PM   #5
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Adding ground to electric water heater


Yes you can connect the water heater ground screw to this new ground system provided that the latter includes a wire to the panel neutral bus bar.

You would need the following to be up to date:

1. A #6 copper wire from a ground rod to the breaker panel neutral bus bar.

2. A #4 copper wire (electrical service 101 to 200 amps, #6 for service 100 amps and under) from the main cold water pipe (if metal) within 5 feet of where it enters the foundation and without the water meter in between, to the breaker panel neutral bus bar.

3. #6 copper connecting all of the various ground rods (if more than one) to each other and to the aforementioned water pipe connection.

4. #6 copper connecting metal portions of the plumbing system separated by plastic portions. (#4 if a circuit of more than 100 amps passes near any of the plumbing relying on that wire for bonding to the ground rod(s) )

5. A length of #6 copper connecting the cold inlet to the hot outlet of the water heater, and a similar piece across the inlet and outlet of the water meter. (Or #4 if that applies to part 4)

Either part 1 or part 2 must be a continuous (unspliced) wire. The rest may be piecemeal using portions of each other or part 1 or part 2 to achieve the complete path.

The conduit from the water heater to the panel, if it once met code for grounding purposes, will still meet code as-is unless proven to not be a good grounding path or unless modified. The plumbing, if metal or bonded as part 4 above, will serve as an adequate ground for safety purposes.

A ground wire sized for the water heater power conductors may be run separately (and also protected from damage) from the ground screw on the water heater to the panel ground bus or to any point on part 1 or part 2 or part 3.
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Last edited by AllanJ; 03-05-2012 at 05:32 PM.
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Old 03-05-2012, 07:00 PM   #6
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Adding ground to electric water heater


Thanks AllanJ.

Just to be clear - I connected the WH ground to the clamp which connects the new #4 ground to the cold water pipe. This #4 wire runs to the ground rod, which is also connected to the panel per (2009) code, and I'm *assuming* he did it right.

If I'm reading you right, you seem to be in disagreement with Jim Port above?

Interesting, (referring back to the "assuming he did it right" comment above), I'm pretty sure that your #2 was not done... there was no copper bonding wire added between the panel and the cold water entrance - unless there was an existing connection that he reused.

#5, don't have a hot-cold bond... nor have I ever seen/heard of one in my limited experience in this area. I wonder if this is universally required?

Re: your last comment, what is required to "protect from damage" the ground conductor? Presently I have an insulated solid copper wire following (but not inside) the conduit for a few feet, then spanning a few inches to the cold water pipe.

Thanks again.
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Old 03-05-2012, 07:07 PM   #7
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Adding ground to electric water heater


Quote:
Originally Posted by tadc View Post
My followup question(and I'm just trying to understand, not argue) is "why" using the bond conductor is not allowed?
Because all it does is equalize the grounding means with earth potential. It does not provide a continuous conductive path back to the panel (earth doesn't count). Also, most water heaters these days have non-metallic pieces somewhere in the plumbing fittings, so there is no electrical continuity from the tank to the plumbing.
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Old 03-05-2012, 08:42 PM   #8
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Adding ground to electric water heater


YOu said there was a ground rod near the water heater with a fat wire from that to the cold water pipe above the water heater. That by itself is not a qualifying place to attach a wire from the ground screw on the heater. But you can make it into a qualifying location by continuing a #6 wire to the panel if not already.

The cold hot bond above the water heater I think is a new requirement although it was an option for a long time. This provides bonding to ground of the entire hot water portion of the plumbing.
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Old 03-05-2012, 09:14 PM   #9
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Adding ground to electric water heater


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Originally Posted by fa_f3_20 View Post
Because all it does is equalize the grounding means with earth potential. It does not provide a continuous conductive path back to the panel (earth doesn't count). Also, most water heaters these days have non-metallic pieces somewhere in the plumbing fittings, so there is no electrical continuity from the tank to the plumbing.
I see - I should have mentioned in my original post that the ground rod is also connected to the panel, so the cold water pipe clamp is connected to the panel via both being connected to the ground rod.
Quote:
Originally Posted by AllanJ View Post
YOu said there was a ground rod near the water heater with a fat wire from that to the cold water pipe above the water heater. That by itself is not a qualifying place to attach a wire from the ground screw on the heater. But you can make it into a qualifying location by continuing a #6 wire to the panel if not already.

The cold hot bond above the water heater I think is a new requirement although it was an option for a long time. This provides bonding to ground of the entire hot water portion of the plumbing.
I assume this is "just in case" something gets grounded to the hot side by mistake? In my case I'm not concerned about this, the hot water plumbing is not very extensive and is easily traced out in the basement - there's nothing connected to it.

Thanks again for your input.

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