View Full Version : electric water heater

December 17th, 2002, 02:31 PM
how do I wire a new 240v water heater? the wiring diagram says black to black, red to red and ground to the green screw. my power supply though, is a black, red and white (neutral) wire.

December 17th, 2002, 02:39 PM
I take it that you are talking about the house wiring when you said black red white wires.

What size are these house wires?
What size breaker protects these house wires?
Is this water heater within sight of the panel breaker or do you have a form of disconnect if not in sight of the breakers in your panel?
what size water heater do you have and what are the heating elements watt ratings?
You did not mention a bare or green wire in that house wire. Is this in conduit or a Romex cable?
Do you have a bare or green wire in with this house wiring?

The above is needed to ensure you are safe.



December 17th, 2002, 02:47 PM
I take it that you are talking about the house wiring when you said black red white wires.

What size are these house wires? Romex type 10/3 without ground
What size breaker protects these house wires? 30A
Is this water heater within sight of the panel breaker or do you have a form of disconnect if not in sight of the breakers in your panel? not within sight of panel
what size water heater do you have and what are the heating elements watt ratings? 50G 4500w total
You did not mention a bare or green wire in that house wire. Is this in conduit or a Romex cable? Romex type 10/3 without ground
Do you have a bare or green wire in with this house wiring? n0

The above is needed to ensure you are safe.



December 17th, 2002, 05:08 PM
Guest you need to read my reply. Then go to the bottom of the page and click REPLY. Then type in what you want to say. Then go to the bottom of the page the click SUBMIT. Then we can see what you have to say. Hope this helps



December 18th, 2002, 07:53 AM
ok, i'll try again. Yes, the existing house wiring which begins at the breaker panel and terminates in a box with a three prong (dryer type) outlet near the water heater.

1.) This wire is a romex type 10/3 without ground. There are two hot (black and red) wires and one neutral (white) wire only
2.) This is a dedicated circuit protected by a 30A breaker.
3.) This water heater is not within site of the breaker panel and does not have any form of disconnect (other than unplugging the cord which was how the deceased water heater was wired).
4.) The new water heater has a 50 G capacity with two 4500W elements.
Hope this helps us both.

December 18th, 2002, 10:46 AM
will assume 30amp breaker you speak off is a DP(double pole) breaker.You may use this breaker for W/Heater circuit. However the 10/3 cable you mention RD/BLK/WHT is not allowed for this circuit, nor would it be allowed for dryer for yourself in future. You will need to run a #10/2 with ground be it green or bare. Also YES a non fusible disconnect switch will be required if W/H is out of sight from breaker (AS STATED).Disconnect will need to be at W/H. You can use what ever is most economical for you for this disconnect as long as it is a doublepole disconnect, must disconnect both hot leads from breaker to W/H. You may use your green or bare wire in that romex as your EGC for that disconnect panel. Anything missed here will be picked up by the main man here WG. GL2U Proper installation of romex can be found on home page wiring designs.

December 18th, 2002, 01:36 PM
Wannabbee, we have a rule that may be able to be used in this scerneio reidentifying a romex cable conductor from any color to green as discribed below. The one resistance is the part requiring only qualified maintainence people. Question is who is "qualified"

Qualified Person. One who has skills and knowledge related to the construction and operation of the electrical equipment and installations and has received safety training on the hazards involved.

(B) Multiconductor Cable. Where the conditions of maintenance and supervision ensure that only qualified persons service the installation, one or more insulated conductors in a multiconductor cable, at the time of installation, shall be permitted to be permanently identified as equipment grounding conductors at each end and at every point where the conductors are accessible by one of the following means:
(1) Stripping the insulation from the entire exposed length
(2) Coloring the exposed insulation green
(3) Marking the exposed insulation with green tape or green adhesive labels

Using this rule it would lead me to believe that green tape or stripping of that wire to bare may be done to reidentify that white wire as a grounding wire.

Then the form of disconnect is a different rule;

422.33 Disconnection of Cord-and-Plug-Connected Appliances.
(A) Separable Connector or an Attachment Plug and Receptacle. For cord-and-plug-connected appliances, an accessible separable connector or an accessible plug and receptacle shall be permitted to serve as the disconnecting means.

This leads me to believe that this 30 amp rated cord and plug on the water heater would meet the rules of the NEC.

Go into your panel and find the white wire of this water heater branch circuit and slice off the isulation. Then ensure the black and red wire is connected to the two lugs of your double pole breaker.

Go to your water heater and again strip the white wire insulation off while inside that 30 amp receptacle. Connect this stripped wire to the center screw of that receptacle. Then connect the red and black wires to the outside screws of that receptacle.

When the pigtail is to connect to the water heater. The center wire of the flat cord is to connect to the green screw of the water heater and the black and red wires wire nut to the black and read wires of the water heater.

Now there is one discrepency in the above. The center screw is silver in that receptacle and that silver screw should be painted green.

Hope this helps


December 18th, 2002, 02:08 PM
yes, I think that does help. That is the same way the old heater was wired albeit with a dryer power cord plugged into the three prong receptacle. I want to do a tidier job though using fexible metal conduit from the wall box to the water heater instead of the receptacle and cord. Do I understand correctly that I can use the white neutral wire as the ground wire so long as I strip the insulation from the wire that is within the breaker panel and the wall box? What is the reason for stripping the insulation?

December 18th, 2002, 02:22 PM
White depicts grounded [aka neutral current carrying]

Green or bare depicts grounding [aka equipment grounding conductor not current carrying except momentary during a faulted condition or dead short to noncurrent carrying metal that you touch.

The receptacle and dryer cord was you form of disconnect that is required.

Normally you would install your romex cable to the location on the wall behind the water heater that is accessible. Then install a non fused disconnect panel. Then install 10/2wGrnd romex between that nonfused disconnect and the water heater.

Some install flex over the Romex cable between the water heater and the nonfused disconnect some do not.

You must use romex connectors to secure these cables to the disconnect and to the water heater.

You must have a form of disconnect for this water heater. I advise to avoid a fuse style disconnect. The resistance heat used in the water heater is very hard on making the contacts fail on those screw in type fuses. Fuses are not necessary. Most common form of disconnect is a weatherproof nonfused air conditioner disconnect. No fuses to cause problems, least amount of connections required, and less expensive and is rated in amps to carry the load of the water heater.

Hope this helps


December 18th, 2002, 02:43 PM
yes, that helps. I need to learn more about the bare/green grounding wire vs the white grounded neutral current carrying wire. It kind of baffles me why the white AND bare/green ground wires go to the same grounded bus bar at the breaker panel.

December 18th, 2002, 03:22 PM
We don't want the white wire that carries current to be touching the bare wire that is supposed to make sure no noncurrent carrying metallic parts such as washer or range metal frames become energized.

The white wire carrying the return path completing a 120 volt branch circuit. This white grounded leg carries current back from you 120 volt appliance through the panels and back to the center tap of the Utility Company's transformer where you hot wire current comes from. This completes the circuit.

The white wire carrying the unbalanced load as a return path for two hot wires out of sync with each other having 240 volts between those two hot wires. The two hot wires will counter act any current from each other until a 120 volt component is used within a 240 volt appliance. Then that creates more current on one hot wire causing an imbalance the other hot wire can not counteract. Then this white true neutral will carry that unbalanced load back to the utility company's transformer where the two hot wires get their energy again completing the two circuits.

Then we have a bare or green wire isolated from the white wires that are an equipment grounding conductor. This green or bare wire is supposed to carry zero current unless a faulted condition [dead short hot to metal frame of appliance that you touch] happens. Then this green or bare wire carries a huge amount of current but only long enough to cause a breaker to trip due to what is called an interupting rating that is supposed to trip that breaker rapidly during a dead short condition. This green or bare wire is designed to protect people from electrical shock.

In any location after the wires leave the main service rated panel [that panel that contains the main breaker or shut off and is in direct contact from the meterbase with unfused wires] any green or bare wires after leaving that main service panel must never touch any hot or grounded [aka white or gray] wire.

The reason for this is that if a hot or white wire touches that bare or green wire that is directly connected to all metals that you normally touch including any metal water faucets to any appliance metal shell or casing, will cause electricity to be exposed to your touch and expose you to electrical shock.

Now we get inside the main panel and anywhere on that service from the weatherhead through the meter base into the main service rated panel. In the above listed locations the bare or green wires must be married [made one with] the white or gray neutral wires and their grounding or neutral bars.

Then you think wouldn't that then energize metals inside the house that you touch. No electricity will take its easiest path to travel. The electricity inside that main service area is directly connected by a big insulated neutral wire to the center tap of the utility company's transformer or to earth through the grounding electrode conductor connected to the ground rod etc. in direct contact with earth. These two paths obsorb any stray currents into the earth or to the source of the power being the utilty transformer. The electricity does not want to back track into the house because there is not good place for that electricity to travel except right back inside the main panel where it is trying to leave. Therefore any stray current flows to the transformer center tap or to earth. Most often being the transformer because it most likely is the source of that current in the first place.

Then we want the grounding [bare or green] and the neutral [white or gray] and their grounding and neutral bars and the metal case of that main service rate panel all connected together with the big neutral wire going to the utility transformer and to earth through the grouding electrodes in contact with earth. REason for this is massive charges of electricity [main concern is lightening]. We want all we can get to route this high power surge of lightening back out of the house through the big neutral conductor to the utility company transformer or to earth instead of where the kids and wife are. This is why we marry the bares, green, white, and gray wires together as one entity. Kind of like a big gate or closed door trying to keep that big lightening surge from entering the house. You have no idea how often smaller lightening charges hit houses from any direction and is dissapated by the big neutral wire or grounding wire to earth. This is a common happening that we don't even notice. This marrying all grounding and grounded together quietly routes those power surges back out of the house and we didn't even know our house got a light charge of lightening.

Problem is lightening can do anything it wants. Power concerning lightening is unlimited in electrical power and mind can be boggled just trying to get a picture just how much power lightening can generate. Lightening can be so powerful that it can travel horizontal without any conductor other that particles of air. When we get hit with this much lightening power then all bets are off. At least marrying those to systems green, bare, white, gray together will catch some of that power and guide it back out of the house. The rest of that massive lightening strike is evidenced in fires and damaged homes. Just too much power to handle at times. We got the best we can set up and this marrying is part of that plan concerning lightening.

Hope this helps some


December 18th, 2002, 08:19 PM
since there is no white neutral conductor wired to the water heater does this mean that the heater uses all electricity supplied to it? And the "ground" wire (which is really the white wire with the insulation stripped off) that is connected to the screw on the frame never carries any current except in the case of a ground fault?

December 18th, 2002, 09:19 PM
sorry about being wrong on this porcupine, unaware of this ruling. Will have to pass it along if ever comes up again, assume a gray line here though with some inspectors who may want to see a piece of paper. But hey if it's in writing I'd go for it. Another reason I guess for being wannabee! GL2U

December 19th, 2002, 01:32 PM
Wannabbee, the only gray area is the use of the dryer pigtail that has a silver screw being used as a green screw. If I looked it up I believe you are allowed to paint a screw green. However the listing of this dryer plug being three prong may be argued that you would not be using that three prong plug with a silver screw as a grounding connection even if reidentified.

If the dryer receptacle was replaced with a 30 amp 240 volt receptacle with two hots and a green grounding screw then there would be no gray are if the NEC rule. I provided the NEC rules so you can look them up. What I provided though is a copied section of that set of rules.

porcipine, you are correct the electricity is only fluctuating back and forth between the two hot wires yet it is still a flow of current.

If we were talking about a 120 volt circuit the white grounded leg is only a return path to complete the circuit.

Either the 220 volt as you have it or the 120 volt with a grounded leg the current still flows the same just point of joining is in different location. One is not more efficient than the other.

However your statement that it uses all the electricity would be incorrect. Power factor would be calculated to see how much of hte electricity is efficiently used to provide electrical work. I do not know of any electrical circuits that would be considered with a power factor of 1. Transformers to my knowledge is the most efficient and best I know of is .99 of 1. 1 being a perfect power factor.

Yes the white wire stripped to be identified as a grounding conductor is designed not to carry current unless a faulted [short circuit] circuit occurs.

Hope this helps


December 20th, 2002, 08:17 AM
I installed the water heater yestrday. And I used the existing 30A power supply cord and 30A receptacle instead of new flex. Your explanations and definitions helped. I knew this was probably the correct way to do it since the old water heater was wired this way. But felt more comfortable with the info and methodology you (Wg) provided. I stripped the insulation off of the "white" wire on the end of the pigtail and twisted the strands together. Also designated white wire at receptacle and in panel as ground wire.

December 20th, 2002, 01:27 PM
You did good you asked the questions to make you feel more secure in your safety. Wish everybody would do the same before they buy materials or do the job. Any question asked can be that one hazard resolved before it appears.

You did good