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Clothes Dryer 240 volt GFCI protection?


dtontarski

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I routinely recommend that laundry area 120 volt receptacle outlets be updated and protected by GFCI circuitry, but what about 240 volt electric dryer receptacle outlets?

Don't these circuits also provide shock risks?

I had an engineer ask me this....why microwaves can have metal racks, and what is natural gas....all on one inspection.

I fielded the last two all right....but I wasn't sure how to respond to if the clothes dryer 240 should be updated to GFCI.

Dave Tontarski

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I realize that I can recommend anything I wish...my question was asked in order for me to gain a better understanding about how to field a question from a client on this topic.

Just because it is not a code requirement doesn't reduce this potential hazard.

I think it would be pretty lame to just say it isn't required by code.

Is there a sound technical explanation for why it isn't?

I was just looking for suggestions for an educated response.

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Hi,

It sounds like he was gaging how much knowledge you have by asking you about something that's so nebulous that an engineer is likely to know it but the average Joe won't. Maybe he wanted to know how credible you are and wanted to see if you'd try to invent some off the cuff answer just to appear smart.

If I'd known he was an engineer asking me those questions, I might have responded with something like, "I'm not really sure; you're an engineer and you've probably got a better understanding of this stuff than I do. What do you think is the reason?"

ONE TEAM - ONE FIGHT!!!

Mike

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Yeah,

I think he was testing you. I've only seen them on hot tubs and such, so I posed the question to google in a way that I thought that a curious engineer might have asked it with, "Is there such a thing as 240-volt ground fault circuit interrupters?" and got some interesting results. One of those was a discussion about 240-volt GFCI's on Mike Holt's forum and I think it's probably it's just the kind of stuff an engineer probably sits around thinking about. Me? I'm too dense to follow half of the results that were kicked up.

OT - OF!!!

M.

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My opinion is...

Basically you have "controlled" electrical situations and "uncontrolled" electrical situations. (As to what is plugged into a given electrical outlet...)

Uncontrolled...

As for a washer outlet, there may be two 120V plugs there and the homeowner can plug anything they want into the additional plug. Then you have the potential of handheld devices, extension cords, etc. posing a shock hazard. A dog could chew on an extension cord. A kid could cut an extension cord with scissors, a cord could have damaged insulation and the wires exposed, a handheld device might malfunction and energize a metal part, etc. No telling what a homeowner might plug into such an outlet!

Controlled...

As for a 240V dryer, there is only one plug. Only the dryer can be plugged in. If everything is manufactured, wired, and installed properly, then there would not be a shock hazard to the homeowner. The metal case of the dryer would be grounded. If a hot wire came in contact with the metal frame of the dryer, this would shunt the electricity to ground and trip the circuit breaker. So no need for a GFCI in my opinion.

Then look at case history...

Has anyone ever been electrocuted by a dryer which was properly manufactured, properly wired, and connected to a properly wired electrical system?

Then look at two wire (non grounded) hand held appliances, three wire grounded hand held appliances, and extension cords. Many people have been electrocuted by these. These are under the control of the homeowner. They modify things. They use 3 prong to 2 prong adapters to defeat the 3rd grounding plug so they can use 2 wire non-grounded extension cords, etc. All sorts of possibilities for dangerous situations!

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Billy_Bob, your answer doesn't explain the requirement on a hot tub circuit, in fact, your answer would indicate no need for a GFCI circuit on a factory hot tub.

Note that code also doesn't require GFCI on any other 220 outlets no matter if they are in the garage, exterior, kitchen, etc.

Well a hot tub is a different situation. Here you have people in the water and the potential for water leaks onto electrical devices.

But....

How about this... How about we just go by "case history"?

That is have people been shocked / electrocuted in or around hot tubs? The answer is yes. So therefore to prevent these things from happening again, it is a good idea to install GFCI's.

AND... For cases where there has NOT been a case history of people being shocked / electrocuted, there is no need for additional protection necessarily.

THAT is basically how the codes come to be. Someone is shocked or electrocuted, someone dies. Then everybody says "What can we do to prevent this from happening again?" The cause of the problem is found, new products are designed, new codes are written and adopted.

An extreme example is there is no requirement for a GFCI to be installed on automobiles. Being electrocuted by a 12 volt DC car battery is not a problem!

At the other extreme, take the example of nightclubs. There have been some nasty fires with great loss of life. Therefore all sorts of codes are in place to prevent these things from happening again.

Or "high rise buildings". There have been many nasty fires with great loss of life. So they really throw the code book with tons of rules at a high rise situation. And they make darn sure the building owner's comply to the "T".

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I routinely recommend that laundry area 120 volt receptacle outlets be updated and protected by GFCI circuitry, but what about 240 volt electric dryer receptacle outlets?

Don't these circuits also provide shock risks?

I had an engineer ask me this....why microwaves can have metal racks, and what is natural gas....all on one inspection.

I fielded the last two all right....but I wasn't sure how to respond to if the clothes dryer 240 should be updated to GFCI.

Dave Tontarski

I have always relied on a simple phrase and it is :I don't know! But I will do some research and get back with you..

It works every time and folks really do appreciate it when you say it and don't try and BS your way out.

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That only happens in the movies, usually with the protagonist lashed to a bare bedspring

Take it from a guy that's been part of a 12 VDC circuit- an automotive battery can light you up pretty darn good.

Next time you're all sweaty put your forearms on the positive and negative. It's invigorating.

I did that on my sons car not long ago and I wet myself![:-monkeyd

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That only happens in the movies, usually with the protagonist lashed to a bare bedspring

Take it from a guy that's been part of a 12 VDC circuit- an automotive battery can light you up pretty darn good.

Next time you're all sweaty put your forearms on the positive and negative. It's invigorating.

Better yet, pull one of the plug wires off a plug while the engine is idling and hang onto the end of it as hard as you can for as long as you can.

OT - OF!!!

M.

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That only happens in the movies, usually with the protagonist lashed to a bare bedspring

Take it from a guy that's been part of a 12 VDC circuit- an automotive battery can light you up pretty darn good.

Next time you're all sweaty put your forearms on the positive and negative. It's invigorating.

Better yet, pull one of the plug wires off a plug while the engine is idling and hang onto the end of it as hard as you can for as long as you can.

OT - OF!!!

M.

That hurts like hell, but then again it's no longer only 12 volts.

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