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Electric water heater getting 120V to ground on each feed but 0V between them. Bad breaker?

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Electric water heater getting 120V to ground on each feed but 0V between them. Bad breaker? m_p_v_13 01-12-2008
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Posted by m_p_v_13 on January 12, 2008, 12:38 am
Water heater was not providing hot water. I replaced elements after
testing showed resistance was out of spec (6 ohms instead of 10-15).
Still no hot water. Check voltage coming into heater with Simpson
Analog meter. Reading is 0 volts between the two wires, but about 115V
from each wire to ground (the tank).

This seems like I must be getting the same (in phase) 120 V power to
each lead instead of the separate (180 degree out of phase) power
signal.

The wiring has not changed!

I do notice that the circuit breaker for the water heater is "soft".
It does not have the snap and spring tension of other similar breakers
in the box.

Is it possible for a breaker to fail in this way?


Thanks for any help.


Posted by Leroy on January 12, 2008, 12:55 am
m_p_v_13 wrote:
> Water heater was not providing hot water. I replaced elements after
> testing showed resistance was out of spec (6 ohms instead of 10-15).
> Still no hot water. Check voltage coming into heater with Simpson
> Analog meter. Reading is 0 volts between the two wires, but about 115V
> from each wire to ground (the tank).

Sounds like one leg is open, either in the wiring or in the breaker.
If you feel competent enough, pull the panel cover and measure
the two hot lines at the breaker. This should help you diagnose
it. Do NOT do this if you're not familar with the procedure and
are the least bit wary doing it.

Yes, a breaker can fail in this fashion, and if it has, the panel
cover will have to be removed to replace the breaker.

Leroy


Posted by m_p_v_13 on January 12, 2008, 1:16 am
> m_p_v_13 wrote:
> > Water heater was not providing hot water. I replaced elements after
> > testing showed resistance was out of spec (6 ohms instead of 10-15).
> > Still no hot water. Check voltage coming into heater with Simpson
> > Analog meter. Reading is 0 volts between the two wires, but about 115V
> > from each wire to ground (the tank).
>
> Sounds like one leg is open, either in the wiring or in the breaker.
> If you feel competent enough, pull the panel cover and measure
> the two hot lines at the breaker. This should help you diagnose
> it. Do NOT do this if you're not familar with the procedure and
> are the least bit wary doing it.
>
> Yes, a breaker can fail in this fashion, and if it has, the panel
> cover will have to be removed to replace the breaker.
>
> Leroy

Thanks Leroy.

If one leg were open, wouldn't I get a reading of 0V for that wire
versus ground?


Posted by Leroy on January 12, 2008, 1:27 am
m_p_v_13 wrote:
>
> If one leg were open, wouldn't I get a reading of 0V for that wire
> versus ground?

No. The open line would 'float' to the voltage of the working
hot wire.







Posted by Leroy on January 12, 2008, 1:35 am
m_p_v_13 wrote:
>
> If one leg were open, wouldn't I get a reading of 0V for that wire
> versus ground?

Think of it as a voltage divider circuit. you've got 115 volts
going into a 15 ohm resistor going to a 20 Kohm analog
meter to ground. voltage would barely drop aacross the
hw heater element.






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