reverse polarity

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jxofaltrds

Senior Member
Location
Mike P. Columbus Ohio
Occupation
ESI
Re: reverse polarity

"does anyone know how a house gets wired reverse polarity?"

A house does not get reversed polarity.(I guess it could happen but has anyone ever seen it?)

It is a "internal" thing.

Can you be more specific?

Mike P.
 

iwire

Moderator
Staff member
Location
Massachusetts
Re: reverse polarity

If the POCO did hook you up hot and neutral misplaced you would not have a live service.

You would have a kaboom! :D

At least in a metal water pipe neighborhood.
 

jimwalker

Senior Member
Location
TAMPA FLORIDA
Re: reverse polarity

I did here of it happening here a few years ago.The poco reversed a neutral and hot to an apartment building.Heard it was to the tune of about 8 grand.They now want to see plenty of white tape and they check.
 

wildman

Senior Member
Location
Georgia
Re: reverse polarity

depatie.....got a call about two weeks ago...customer's washing machine (15 years old) had finally bit the dust....purchased a new one from the local department store...ran ok for 3 days then died! Department store sent out a repairman....motor and controls burnt up....said reason was reversed polarity at receptacle (duplex-125 volts-isolated on 20 amp circuit...said customer to call in an electrician to correct polarity! Took washer with him to check on factory warranty. I found polarity reversed and corrected before I left! customer wants to know if polarity problem caused her new washer to burn up! Yes, no, maybe! did not check other receptacles throughout the home...customer was only concerned with washer! comments please!!
 

hurk27

Senior Member
Re: reverse polarity

I would like to know how reverse polarity would cause a failure in the washer too! as far as the load is concern AC has no polarity? This sounds like a cop out to find a way to charge the customer to make money off them. The only thing that reverse polarity would do is change which wire was referance to the EGC. Now if this was a 240 volt multi-wire circuit, then yes it would cause 240 volts to be applied to the washer. But it doesn't sound like the case here.
 

jimwalker

Senior Member
Location
TAMPA FLORIDA
Re: reverse polarity

Seems strange in that whatever electronics it had could work 3 days.If the polarity was a problem i would think it would burn up instantley.I would love to see its schematic

[ February 12, 2004, 06:45 PM: Message edited by: jimwalker ]
 

wildman

Senior Member
Location
Georgia
Re: reverse polarity

spoke with owner today...still waiting to hear from factory...department store... I will post back when I get an answer!
 

electricman2

Senior Member
Location
North Carolina
Occupation
Retired Electrical Contractor
Re: reverse polarity

How did the old washer run 15 yrs on reversed polarity? I don't believe that was what smoked the new one.
 

jimwalker

Senior Member
Location
TAMPA FLORIDA
Re: reverse polarity

Only posibility i can see is if they had anything connected internal between ground and what was to be neutral.Still cant see how that burns out a motor,unless its one of these variable speed motors controled electronically.
 

jimwalker

Senior Member
Location
TAMPA FLORIDA
Re: reverse polarity

I seen a microwave oven do this once.A diode was sent to the grounded frame.They might have had something like an arrester built in on the circuit board.Really would need to see the schematic,that tells everything.If there is no connection to the frame other than ground wire then i agree polarity wouldn't matter
 

racraft

Senior Member
Re: reverse polarity

It is entirely possible that this washing machine has electronic controls, while the old model did not.

Newer appliances with electronic controls might be more susceptible to a polarity and/or ground problem since they need a dc voltage to power the control module. An older appliance with no electronic controls wouldn't care about polarity.
 

wanderer20001us

Senior Member
Re: reverse polarity

With newer equipment, especially electonically controlled appliances, internal surge protection and control board reference the neutral and ground in specific ways. MOV's and cicuit board that should see less than 2Vp-p between neutral and ground cannot handle line voltage for very long. I'm surprised it lasted three days.

The motor itself should not have been electrically damaged, though. Maybe the excess heat from other component failure caused the damage.

Sam A. - PE
 

jimwalker

Senior Member
Location
TAMPA FLORIDA
Re: reverse polarity

In the event that this was damaged by reversed polarity,a question arises as to liabilty.Most stores deliver and set up appliances.Also would want to read the manuel that comes with it.If the manuel mentioned the grounded outlet and properly wired (most will) then liability might shift to the installer.They must understand the possibilties in older homes.Chances of K&T being reversed is high and ungrounded systems even higher.I have often found on new homes where helpers got careless.Very important that the system is checked after a trim.
Might add that some of the new motors are complex multi speed controled by that circuit board.

[ February 13, 2004, 10:32 AM: Message edited by: jimwalker ]
 

hurk27

Senior Member
Re: reverse polarity

By Racraft: Newer appliances with electronic controls might be more susceptible to a polarity and/or ground problem since they need a dc voltage to power the control module.
Yes any solid state electronics do need DC current. But the power leaving the receptacle is still 120 volts AC not DC and if the line and neutral is reverse you still have AC power to the washing machine. after it get's there it is changed to DC by rectifiers and filters but this at the washer not at the receptacle


By Sam A.: With newer equipment, especially electronically controlled appliances, internal surge protection and control board reference the neutral and ground in specific ways. MOV's and circuit board that should see less than 2Vp-p between neutral and ground cannot handle line voltage for very long. I'm surprised it lasted three days.
I can not think of any reason that an electronic system designer would use anything on the DC side of a electronics control circuit to reference the ground as the ground is only there for fault current and should not be used in any way to control a washer. And while some designers might install a MOV device to try to block any transient spike between the neutral and ground. It wouldn't be below the 130 volt threshold of a MOV that would be used on a line to neutral as this would be a very poor design. Most transient spikes that damage equipment are line to neutral and this is because this is where the load should always be connected. so why would you install a MOV between neutral and ground when any surg's between these would not have a load to damage. Also if a MOV with a 2 volt threshold was installed between the ground and neutral it wouldn't last any way as any voltage drop in the neutral would cause current in the MOV as the most circuits will have more than a 2 volt drop. the EGC wont have the voltage drop as it will be at the main neutral bar potential. because there is no current on it to cause a drop.

I still say the reversal of a hot and neutral should not have cause this washer to fail in any way. unless of course the circuit was a multi-wire circuit and the reversal was with the hot from the other phase leaving 240 volts at the washer receptacle.
 
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