# Unusual voltage reading



## backstay (Feb 3, 2011)

240 volt delta. The WH isn’t looking at voltage to ground, why are you?


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## jbfan (Jan 22, 2007)

backstay said:


> 240 volt delta. The WH isn’t looking at voltage to ground, why are you?


Well, that's how I have always done troubleshooting.

Thanks for the answer.
I have never really worked on a delta system.


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## backstay (Feb 3, 2011)

jbfan said:


> Well, that's how I have always done troubleshooting.
> 
> Thanks for the answer.
> I have never really worked on a delta system.


Water heaters will screw you up when you start to put that meter to ground.


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## micromind (Aug 11, 2007)

330 is WAY high for the high leg of a ∆ system. in theory, it'll be 208. 

Is the 240 side of the transformer grounded? If not, you'll get oddball readings.


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## gpop (May 14, 2018)

Gets a little confusing on where its 3 phase and where its single phase. 

Im reading this as 3 phase 480 needed single phase 240v so installed 480-240v transformer and used 2 poles of a 3 phase breaker. One pole went bad so switched to the spare pole. 

If that is correct did you ground the center point of the transformer ?.


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## jbfan (Jan 22, 2007)

gpop said:


> Gets a little confusing on where its 3 phase and where its single phase.
> 
> Im reading this as 3 phase 480 needed single phase 240v so installed 480-240v transformer and used 2 poles of a 3 phase breaker. One pole went bad so switched to the spare pole.
> 
> If that is correct did you ground the center point of the transformer ?.


480 was single phase, and it has been so long since I wired this thing up inside the transformer, I don' remember if I grounded anything other than the case and the incoming and outgoing feed.

I will look at the diagram tomorrow and add a picture.


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## CMP (Oct 30, 2019)

The transformer secondary coil is a separately derived system and it is required to be bonded to the grounding electrode system or the building steel. When it is left floating there is no real connection to ground, other than capacitive coupling. More importantly there is no direct path for short circuit current to trip the over-current device when a fault occurs or an element goes bad. A failed heating element can put stray currents on the piping system and leave no way for the breaker to trip and remove the hazard. How to bond it depends on the transformer type you have.


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## lu308kpw (Oct 23, 2021)

jbfan said:


> Somewhere back in 2001/2003 time frame we had a 480 volt water heater that gave up the ghost.
> 
> We couldn't find one to match, so we decided to put a stepdown transformer to 240 and install a single phase water heater.
> 
> ...


#1 Get that Transformer bonded/grounded correctly. It probably is not correct at this time. Also, if the transformer has two wiring diagrams; make certain you are using the correct one. If necessary, Shut it down, break all terminations and then re-terminate according to diagram.
#2 Get that breaker in the trash can and replace. There is no such thing as switching from the non-working leg to a working leg of a breaker. If a leg on a breaker is bad; then, the breaker is bad... toss it.


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