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Old 08-07-2012, 02:54 PM   #1
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Testing electric element for water heater

Does anyone know how I can test the electric heating element in my water heater? Had a problem a few days ago where the heater didn't work on electric and wanted to rule out the heating element.
Thanks.
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Old 08-07-2012, 03:44 PM   #2
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Does anyone know how I can test the electric heating element in my water heater? Had a problem a few days ago where the heater didn't work on electric and wanted to rule out the heating element.
Thanks.
If you have 10 gallon suburban, the element is located just below the burner tubing. Its near center at the bottom, access from the outer cover. There should be a black plastic cover with ears screwed into the face plate. With power off remove cover, an establish power to the heater. Should read 120 AC across the two screwed wires.
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Old 08-07-2012, 03:56 PM   #3
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If you have 10 gallon suburban, the element is located just below the burner tubing. Its near center at the bottom, access from the outer cover. There should be a black plastic cover with ears screwed into the face plate. With power off remove cover, an establish power to the heater. Should read 120 AC across the two screwed wires.
Vince,
When I tried this as you described, all I get is a big spark and pop the circuit breaker.
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Old 08-07-2012, 04:07 PM   #4
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Vince,
When I tried this as you described, all I get is a big spark and pop the circuit breaker.
Voltmeter is set on 0-200Vots AC? if it is, try another meter. You're producing a short circuit thats why breaker opens.
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Old 08-07-2012, 05:20 PM   #5
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That is not correct.

You will only be measuring the potential across the terminals and not the continuity of the element.

Remove 120 VAC power from the water heater at the power center by opening the circuit breaker.

Select OHMS on your meter. and remove one wire from the element.

Put a test probe on each ear of the heating element.

The meter should show the calculated resistance across the terminals; if it shows "open" or infinite the element is burned out.

How to Test a Heating Element: 9 steps - wikiHow

Using this method for a suburban water heater element of 1000 watts @ 120 volts:

R = (V^2) / P [Where V is the voltage powering the element, P is the power the element uses and R is the resistance.

120Vx120V/1000 = 14 ohms.
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Old 08-07-2012, 05:38 PM   #6
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That is not correct.

You will only be measuring the potential across the terminals and not the continuity of the element.

Remove 120 VAC power from the water heater at the power center by opening the circuit breaker.

Select OHMS on your meter. and remove one wire from the element.

Put a test probe on each ear of the heating element.

The meter should show the calculated resistance across the terminals; if it shows "open" or infinite the element is burned out.

How to Test a Heating Element: 9 steps - wikiHow

Using this method for a suburban water heater element of 1000 watts @ 120 volts:

R = (V^2) / P [Where V is the voltage powering the element, P is the power the element uses and R is the resistance.

120Vx120V/1000 = 14 ohms.
Herk,
When I follow your procedure, I get a reading of 1 (the same as the meter indicates with the probes not touching together- it goes to zero when I touch the leads together). If I change the ears that are touched with the probes, I get a reading of -49.5. ie touch red to top ear and black to bottom- then I change and touch black to the top and red to the bottom. Don't know what to make of that.
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Old 08-07-2012, 05:50 PM   #7
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Meter on the wrong thing. If you are checking ohms, and have one terminal on the disconnected, no way will you get a negative reading on an ohmmeter. Power must still be on, and this should never happen when checking for ohms, (resistance). If the heater has water in it, check from each leg to a metal part of the heater, or the gas line. If you show any resistance, element is blown, and water is shorting it to ground.
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Old 08-07-2012, 06:06 PM   #8
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Herk,
When I follow your procedure, I get a reading of 1 (the same as the meter indicates with the probes not touching together- it goes to zero when I touch the leads together). If I change the ears that are touched with the probes, I get a reading of -49.5. ie touch red to top ear and black to bottom- then I change and touch black to the top and red to the bottom. Don't know what to make of that.
I get the first part. A 1 set in continuity means "open" or infinite resistance.
Zero means dead short (probes touching each other. Continuity is normally used to test diodes.

Try "OHMS" with a 1K or 100 Ohm range.

That you are getting a negative number reversing the ears is a bit unusual. I don't know what to make of that either. Perhaps you are getting a continuity reading through the burst heating element to the ear.

Here is what a burned out element could look like and how a test of a "good" fridge heating element should look like.
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Old 08-07-2012, 06:13 PM   #9
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Meter on the wrong thing. If you are checking ohms, and have one terminal on the disconnected, no way will you get a negative reading on an ohmmeter. Power must still be on, and this should never happen when checking for ohms, (resistance). If the heater has water in it, check from each leg to a metal part of the heater, or the gas line. If you show any resistance, element is blown, and water is shorting it to ground.
Windrider-
OK- let me recap what I just did.

Breaker off.
1 Electric wire off heater
reading on meter 1
Red probe on disconnected terminal Black probe on metal part of heater reading 0
Red probe on terminal with wire black probe on metal part of heater reading is 1
Black probe on terminal with wire red on metal part of heater meter reading -49.5
Black probe on disconnected terminal red on metal part of heater meter reading 0
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Old 08-07-2012, 06:20 PM   #10
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Maybe fuse is out on meter from 1st test. Herk you will get 120 VAC across element if it is open, very simple test.
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Old 08-07-2012, 06:23 PM   #11
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Just to confirm.

What SCALE are you using on your meter? It should be one of the ones that has a little "earphone" symbol on it. This meter has only 3 OHM ranges (200 OHMS; 2000 OHMS and 20K (20,000) OHMS) for example. The next one counterclockwise from the Ohms scales is the diode continuity check setting and is not the one you should be using for this test.

Are there one or two ears on your heating element?

You should be measuring the ohms between the ears (provided there are two there) NOT between one ear and chassis ground.
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Old 08-07-2012, 06:39 PM   #12
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OHMS or 'Little earphones' setting is 200k.
Water heater has 2 ears or terminals where the wires connect to it.
With one wire attached to the heater element I get a reading of 1. When I switch the ear the red and black probes touch I get -49.5.
When I remove the wire (no wires attached to the heater element) I get the same readings. 1 and if I switch the ear the red and black probes touch I get -49.5
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Old 08-07-2012, 06:45 PM   #13
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OHMS or 'Little earphones' setting is 200k.
Water heater has 2 ears or terminals where the wires connect to it.
With one wire attached to the heater element I get a reading of 1. When I switch the ear the red and black probes touch I get -49.5.
When I remove the wire (no wires attached to the heater element) I get the same readings. 1 and if I switch the ear the red and black probes touch I get -49.5
WAY to high. Move it to 200 ohms. You are looking for 14 ohms.

On a 200K scale 14 ohms will look like a dead short.

When the black and read probes touch each other you get -49.5 right?
You need to adjust your zero.
When the probes are touching each other they should read zero.
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Old 08-07-2012, 06:54 PM   #14
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OK- now I get the reading of 1 no matter how I test it. Looks like I will be looking for a new heater element.
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Old 08-07-2012, 07:00 PM   #15
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OK- now I get the reading of 1 no matter how I test it. Looks like I will be looking for a new heater element.
This is on the 200 ohm setting?
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Old 08-07-2012, 07:04 PM   #16
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Yes - 200 ohm. Reading of 1 comes up when I turn the meter on. When I touch the probes together, it goes to 0 (zero).

As I said, I get a reading of 1 no matter how I check.
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Old 08-07-2012, 07:04 PM   #17
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Maybe fuse is out on meter from 1st test. Herk you will get 120 VAC across element if it is open, very simple test.
Yes, I see that. You will see the 120 volts potential whether the heater element is open or shorted. No?

You are just measuring the voltage potential across those two points. If you disconnect the wires from the heating element completely and measure across the two disconnected wires it will still read 120 volts, I am thinking.
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Old 08-07-2012, 07:11 PM   #18
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Now I'm really lost. How does checking across the disconnected wires tell me if the heating element is shot?
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Old 08-07-2012, 07:34 PM   #19
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Yes, I see that. You will see the 120 volts potential whether the heater element is open or shorted. No?

You are just measuring the voltage potential across those two points. If you disconnect the wires from the heating element completely and measure across the two disconnected wires it will still read 120 volts, I am thinking.
Sorta the first test was to establish power to the element.
Now with the "hot" hooked back up connect the meter on 200vac scale and measure the 2nd terminal to the wire to common. that will put meter in series with power supply and measure power thru the element. However if the 1st test shows 120 to the element, test is over, with power, no heat, change element. Sorry for the confusion, just taking one step at a time for the OP.
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Old 08-07-2012, 09:15 PM   #20
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Now I'm really lost. How does checking across the disconnected wires tell me if the heating element is shot?
It doesn't. It just verified you have power or not.If you have power then you can move on to the eleement itself by testing it with an ohm meter.
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