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Thread: Voltage Testing and Electirical Voltage Requirement Question

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    FordMan59 is offline Apprentice
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    Voltage Testing and Electirical Voltage Requirement Question

    OK guys, I'll admit I'm dumb when it comes to electricity. I am suspecting the water heater circuit in my manufactured home is 208V because it's wired with 12 gauge wire and only on a 20 amp breaker, but exactly how do I test the voltage on 208-240V circuits using a DVOM?

    I am looking at this water heater as a replacement for my old unit. https://www.menards.com/main/plumbin...44810308227108 It says requires 240V circuit. I called Rheem/Richmond's technical help line and ask if it could be used on a 208V circuit, the lady I spoke with said she thought so. Is there any possible reason this wouldn't work on a 208V circuit?
    Last edited by FordMan59; 04-24-2016 at 07:09 AM.

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    The only way you would have 208 volts anywhere in your home is if the power company was supplying 208. Which would make all of your outlets 104 volts. Your toaster would be slower to pop up.

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    Check the identification plate on your existing water heater to determine the voltage, amperage and/or wattage requirements. You should select a new unit that matches the old one. The one you have selected seems to be a little large (9,000 watts) for a 20 amp breaker.

    Edit: Although you probably do not have 208 volt power, you could use the 240 volt heater on 208 volt supply - it will just simply put out a little less heat although you will probably not notice it.
    Last edited by Lone Star Charles; 04-21-2016 at 02:26 PM.

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    FordMan59 is offline Apprentice
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    Quote Originally Posted by Lone Star Charles View Post
    Check the identification plate on your existing water heater to determine the voltage, amperage and/or wattage requirements. You should select a new unit that matches the old one. The one you have selected seems to be a little large (9,000 watts) for a 20 amp breaker.

    Edit: Although you probably do not have 208 volt power, you could use the 240 volt heater on 208 volt supply - it will just simply put out a little less heat although you will probably not notice it.
    At first I thought the same thing as you that 9K watts was too much for a 20A breaker. Now, whether this is true or not, I read online that the thermostat on a double element heater prevents both elements from running at the same time, the thermostat starts with operation of the lower element then at some point the lower element shuts off and the upper comes on....???
    Last edited by FordMan59; 04-21-2016 at 04:20 PM.

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    Quote Originally Posted by FordMan59 View Post
    I read online that the thermostat on a double element heater prevents both elements from running at the same time, the thermostat starts with operation of the lower element then at some point the lower element shuts off and the upper comes on....???
    If you read it online, then it must be true. Seriously, compare what you are buying to what you are replacing. There should be an identification data plate on the old heater. If the new one is not very close to the same, you will have to modify something.

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    If you read it online, then it must be true.
    That's what I always thought!

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    FordMan59 is offline Apprentice
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    Got the old water heater out and found that the manufacturing label says it's a 3800 watt unit. After searching high and low for a 3500W water heater that I could use without changing the wiring/breaker I found a Rheem listed on Home Depot's web site that's a 3800W double element and the specs say it can be used with 12 gauge wire and 20 amp breaker. Now, all I have to do is order the water heater and get the floor repaired where the old unit leaked. This is a mobile home and the sub flooring is particle board so I'm afraid to put the weight of another water heater full of water on it for fear it might go through the floor. Thought I'd post this here in case someone else runs upon the same problem I had. Rheem makes a unit that will work with this configuration, the model number is XE30T06ST38U1. Only thing is my old water heater had the water connections in the side and this unit has them on top, no big deal, nothing a little PVC pipe and glue won't fix.
    Last edited by FordMan59; 05-01-2016 at 08:49 AM.

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    You might want to be sure and use CPVC, not just PVC. The CPVC can handle the heat.

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    look in the first part of this forum on electrical. I have included a diagram on hot water tank's wiring - sequential and non sequential. it is a sticky. sequential one element operates then switches to the other one.

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    dha
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    Just like to point out that 208 volts is generally associated with 3-phase power so it it unlikely that any water heater would specify that voltage. As you discovered, a 240 volt heater would be what you need.

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