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I have a customer who has a water heater with 2 elements. The one at the top and bottom are both rated at 4500 watts, but the water heater itself is rated at 4500 watts maximum.

Is each element rated at 120v and 4500 watts?

My guy who is there says that when doing a load test, the water heater is showing 37 amps and tripping the 30 amp breaker. If they are only rated @ 4500 watts, 240 volts, then how can this be? Are they designed where only 1 element can come on at a time?
 

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Donuts > Fried Eggs
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The tank is set up for alternating elements where a master thermostat prevents both from coming on at the same time. They would alternate where the upper element would be high-demand and the lower would be just to maintain temperature.

This thermostat has failed such that they're both energized and shouldn't be, and that's why you're at 200% of your wattage and tripping the breaker.
 

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I have a customer who has a water heater with 2 elements. The one at the top and bottom are both rated at 4500 watts, but the water heater itself is rated at 4500 watts maximum.

Is each element rated at 120v and 4500 watts?

My guy who is there says that when doing a load test, the water heater is showing 37 amps and tripping the 30 amp breaker. If they are only rated @ 4500 watts, 240 volts, then how can this be? Are they designed where only 1 element can come on at a time?
had a bad element do this
 

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IBEW L.U. 1852
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Its very possible that the master thermostat (on top) is acting up. It sounds like its allowing both elements to come on at the same time.
Not the first time I've seen that.
 

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carryyourbooks said:
I have a customer who has a water heater with 2 elements. The one at the top and bottom are both rated at 4500 watts, but the water heater itself is rated at 4500 watts maximum. Is each element rated at 120v and 4500 watts? My guy who is there says that when doing a load test, the water heater is showing 37 amps and tripping the 30 amp breaker. If they are only rated @ 4500 watts, 240 volts, then how can this be? Are they designed where only 1 element can come on at a time?
You wired them 120v when it should be 240v (if I understood right) Only ONE element comes on at a time, so check it out:
4500w/120v= 37.5a

4500w/240v=18.75a.

Did you say your elements are 120 or 240....I don't think they are 120v, they should have them printed right on them. Also is the a new install or are you troubleshooting an existing, previously worked unit??
 

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You wired them 120v when it should be 240v (if I understood right) Only ONE element comes on at a time, so check it out:
4500w/120v= 37.5a

4500w/240v=18.75a.

Did you say your elements are 120 or 240....I don't think they are 120v, they should have them printed right on them. Also is the a new install or are you troubleshooting an existing, previously worked unit??
The elements are a set resistance. You apply half the voltage, you get half the current and a quarter the wattage
 

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carryyourbooks said:
I have a customer who has a water heater with 2 elements. The one at the top and bottom are both rated at 4500 watts, but the water heater itself is rated at 4500 watts maximum. Is each element rated at 120v and 4500 watts? My guy who is there says that when doing a load test, the water heater is showing 37 amps and tripping the 30 amp breaker. If they are only rated @ 4500 watts, 240 volts, then how can this be? Are they designed where only 1 element can come on at a time?
Ask your guy to give you more information, as everyone said the boiler consists of ;
Upper element and upper thermostat

Lower element lower thermostat.

And a disconnect, unless the panel is within site of the boiler.

First I would measure voltage at the disconnect or breaker, it should be on a 2-pole 30right? It should also be 240

Then CONFIRM the resistance reading on the element with a multimeter to prove good, ales chech each element to ground.

If that tests ok I would first observe the wiring, if that checks out, change the top thermostat
 

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I have a customer who has a water heater with 2 elements. The one at the top and bottom are both rated at 4500 watts, but the water heater itself is rated at 4500 watts maximum.

Is each element rated at 120v and 4500 watts?

My guy who is there says that when doing a load test, the water heater is showing 37 amps and tripping the 30 amp breaker. If they are only rated @ 4500 watts, 240 volts, then how can this be? Are they designed where only 1 element can come on at a time?
Top thermostat runs one at a time. Top one heats then once the upper therm us satisfied the lower one then heats till the lower therm conks out.


4500+4500=9000/240=37.5 amps. Hence the one at a time nature.
 
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