scott thompson
Senior Member
- Location
- Anaheim, California
Re: reverse polarity
Gotta agree with Wayne on this one!
The most problematic situation that results from a Reversed Polarity scenario with an AC 2 wire circuit, will involve screwshells + Lamps with screwshells, and some really antiquated lighting fixtures (such as table lamps) with the metallic frame bonded to the lamp socket's screwshell.
Reversing the L-N Polarity in the examples above results in the Ungrounded (hot) conductor being connected to the screwshell base of the typical medium base incandescent lamps (lamp package type A).
The lamp will still operate properly, only the person touching the fixture will still be touching it - and vibrating around 120Hz, with a corresponding rising of hair... AKA Getting Shocked.
If the branch circuit is a multiwire circuit, then reversed polarity could result in 240 VAC being found where 120 VAC should really be at! This would be a great method for releasing the smoke from the washing machine's motor - and makes more sense if the motor ran for 3 days before letting smoke out.
Here's something to ponder... Would it have been possible for someone to change out a 240 VAC receptacle, and install a 120 VAC receptacle?
Something like (maybe) the dryer's outlet being changed to a NEMA 5-15R or 5-20R (125V 15 or 20 amp 2 pole 3 wire grounding receptacle), or maybe someone tapped off the dryer's 240 V circuit and connected a 120 V receptacle to it. Worth checking out...
Situation really smells like a 120 VAC item connected to 240 VAC circuit mixup.
Reversed Polarity on a 2 wire AC circuit has no effect on the operation of an AC load.
There is nothing "polarity different" with the use of a grounded circuit conductor on a 2 wire circuit. It's only grounded - it still carries an Alternating Current, and has a potential of 120V to one of the two ungrounded conductors.
Would be no different if the 2 wire circuit used both ungrounded conductors - intended to utilize 240V for an Induction Motor. Reverse the polarity for that 1? motor, nothing changes.
Leaving the soapbox...
Scott
Gotta agree with Wayne on this one!
The most problematic situation that results from a Reversed Polarity scenario with an AC 2 wire circuit, will involve screwshells + Lamps with screwshells, and some really antiquated lighting fixtures (such as table lamps) with the metallic frame bonded to the lamp socket's screwshell.
Reversing the L-N Polarity in the examples above results in the Ungrounded (hot) conductor being connected to the screwshell base of the typical medium base incandescent lamps (lamp package type A).
The lamp will still operate properly, only the person touching the fixture will still be touching it - and vibrating around 120Hz, with a corresponding rising of hair... AKA Getting Shocked.
If the branch circuit is a multiwire circuit, then reversed polarity could result in 240 VAC being found where 120 VAC should really be at! This would be a great method for releasing the smoke from the washing machine's motor - and makes more sense if the motor ran for 3 days before letting smoke out.
Here's something to ponder... Would it have been possible for someone to change out a 240 VAC receptacle, and install a 120 VAC receptacle?
Something like (maybe) the dryer's outlet being changed to a NEMA 5-15R or 5-20R (125V 15 or 20 amp 2 pole 3 wire grounding receptacle), or maybe someone tapped off the dryer's 240 V circuit and connected a 120 V receptacle to it. Worth checking out...
Situation really smells like a 120 VAC item connected to 240 VAC circuit mixup.
Reversed Polarity on a 2 wire AC circuit has no effect on the operation of an AC load.
There is nothing "polarity different" with the use of a grounded circuit conductor on a 2 wire circuit. It's only grounded - it still carries an Alternating Current, and has a potential of 120V to one of the two ungrounded conductors.
Would be no different if the 2 wire circuit used both ungrounded conductors - intended to utilize 240V for an Induction Motor. Reverse the polarity for that 1? motor, nothing changes.
Leaving the soapbox...
Scott