Dryer vs GFCI

[curt swartz]

No longer true. Most modern dryers now use a 200V 3 phase motor and a VFD (PC board mount) inside. Then they have what’s called a “voltage doubler” circuit for when it is used at 120V, like on a gas dryer, or it just takes in the 208 or 240V single phase and recreates 3 phase for the motor. In addition, the controls are all electronic now and use a Switch Mode Power Supply that can accept anything from 100-240V input without having to change anything. One motor, one control system, one design regardless of where in the world it goes. It’s been that way for about 10+ years now.

the problem now is that our new codes require a GFCI for the dryer and VFDs don’t play well with GFCIs. Some hold, some do not. One thing for sure though, your grounding has to be PERFECT. No cheating, no fudging.

Are you sure? I just looked up replacement parts for several current model top of the line ($1,000+) dryers. The motors are all shown as 120V 60HZ.

Washing machines I get since they have gone to a direct drive model design. The motors need to run in multiple speeds and directions. Dryers are single speed and single direction with minimal load so it doesn't make sense to use a fancy motor and fancy electronics (VFD) to power it.

We have been GFCI protecting the 120V laundry circuit for many years and I have not experienced or heard of many issues. Even if they do use a VFD for the dryer motor it should not be any more of a problem than the washing machine. If anything less since its not constantly changing speeds or directions. Its on or off.

I'm wondering how well GFCI protection is going to work on high efficiency central AC units. Those drives can be much larger than common pool pumps that are know to have issues.

 

[FionaZuppa]

I'm wondering how well GFCI protection is going to work on high efficiency central AC units. Those drives can be much larger than common pool pumps that are know to have issues.

A "up to 18seer" condenser (they really mean system) will use a "2 stage" condenser motor on pump, it's a basic two speed thing. No VFD that I can see.

 

[mbrooke]

And those tend not to bother GFCIs...

Hopefully...

 

[Rdcowart]

Just wait until we have to start adding gfci protection to every dryer circuit.

 

[ptonsparky]

Just wait until we have to start adding gfci protection to every dryer circuit.

You aren’t?




We aren’t either. Next month is hammer time, IIRC.

 

[Chad228]

There are many dryers installed with 4 wire cords that have the jumper installed. Now with the GFCI requirement, those jumpers will be discovered.
When I instructed classes, I would often have appliance repair electricians, and they said it was very common to have the jumper when it was not supposed to be there, and vice versa.
Code first required 4 wire cords for dryers and cook tops back in 96 or 99, doesn't do much good to have a 4 wire cord and the jumper.
How many home owners move, take old dryer, replace the cord to work with new 4 pole receptacle.
Not sure what the solution is.
GFCIs for sure

Question. I had a 3 wire prong on my dryer and bought a new house with 4 prong plug in. Swapped cable on dryer and now my 30 amp gfci trips immediately when plugged in

 

[augie47]

I suggest reading this thread:
Gives credibility to hiring a professional.

How did this clothes dryer circuit start a fire?

But even that catastrophic failure did not ignite the house. No. I still would put more suspect on a weak connection in the panel, and may or may not even be part of the dyer circuit. OP possibly recreating things that had no relevance to the incident, and apparently based on code issues...

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