Old and New Water Heater Wiring

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Old 08-08-08, 06:28 PM
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Old and New Water Heater Wiring

Our cottage was built in Michigan in 1970 and has an electric 240 v water heater. I don't know how old the water heater is but we are in the process of replacing it. The existing wire going to the old water heater is 10-3 with no mention of a ground on the sheath. I have not had a chance to look inside the water heater junction or the service panel to see how a 10-3 wire was used.

In addition, connected to the top metal case of the old water heater is a large bare wire (estimated at 8 guage) that follows the inlet cold water pipe and terminates where the well input pipe goes into the ground - I assume this is a "ground".

Questions:

How should the new 240 v 30 amp water heater be wired and grounded? It would seem that all is needed is a 10-2 w ground wire for 240 v/30 amps?

Does the ground wire from the water heater case to the well pipe provide any other purpose (it is only connected to the water heater) or can this be removed if the new water heater is grounded to the service panel?

My electrical reference says a water heater that is not in sight of the service panel needs a shut off by the water heater. Is this true and what type of "shut off" do I need to install?

Thanks in advance.
 
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Old 08-08-08, 07:27 PM
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If the water heater is not in sight of the panel it needs a simple pull out disconnect like the one on your AC condenser. The 10-3 cable will work, but you need to mark both ends of one of the conductors, preferably the white one with green tape and use it for the equipment grounding conductor.
 
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Old 08-08-08, 10:53 PM
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Majorty of resdentail waterheater { tank type } useally are wired for 30 amp 240 volt circuit and typically use 10-2 NM or #10 THHN/THWN wires.

If some reason if have 10-3 NM just capped off white wire that will be not used in water heater useage due the waterheaters do not have netural connecton at all.

Yes if waterheater is not in sight a disconnection switch will have to be used in there.
{ A simple A/C disconnection switch will serve that purpose very easy. }

Merci,Marc
 
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Old 08-09-08, 08:03 AM
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I love the code. "not in sight" such an arbitrary statement. In one case the panel disconnect could be 100 feet away, but in sight in a large building and in another just feet away but on the other side of a wall just around the corner.

Do the specify what happens if you have poor vision?

I understand the reasoning here but the wording could be improved.
 
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Old 08-09-08, 11:16 AM
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If you check the definitions (Article 100) it states that "within sight" means the specified equipment is to be visible and not more than 50 feet distant from the other.

Not the least bit arbitrary in my opinion.
 
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Old 08-10-08, 01:03 AM
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In my 19 years I have never put a disconnect of any kind for a water heater. When that code was implemented, all it says it must have, your right, a disconnecting means or an approved breaker lock-out. A breaker lock-out when a lock is installed on it prevents the breaker to be turned on. I would opt for Spending under $10 for a breaker lock-out that fits snugly over existing breaker to Buying an expensive disconnect. Other than that are you sure that the bond wire you see clamped to the water pipe does not go to your service panel? The water has to be bonded to the service with a #4 copper and it is usually done at the water heater, cold side only.
 
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Old 08-10-08, 06:44 AM
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Residential grade water heaters are normally a maximum 240 volts. I would have to say that 422.31 (A) from the '08 NEC would apply here. The code referencing the breaker lock applies to appliances rated over 300 volts.
 
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