Electrical Shock While Working On Dryer ?

[Joseph Meehan]

I did not know that. It sounds like a bad idea to me.

[Stormin Mormon]

Yes, I would do that. Good idea.

[Pop]

...

Actually, I don't think it's true. Neither UL nor CSA have allowed anything like that for over my 35 year's experience, and the current rules, including EC definitely do not allow it. An exposed metal part must be either connected to earth, or "double insulated" (which does NOT mean two layers of insulation). The only safety spec number I recall at the moment is the old UL1459 or I could provide more backup. Retired, don't cha know .

Pop

[bob kater]

[Mark Lloyd]

My dryer uses a 3-prong plug. There is a nearby 120V receptacle that is grounded. Do you think it's OK to use that?

[Mark Lloyd]

If the nothing but the heater is working, that should be shut off soon by a thermal circuit breaker or fuse.

[Mark Lloyd]

And it'll be a very long time before no one has them.

I'm considering doing that here, or at least between the dryer and the

120V receptacle (that is grounded).

[Joseph Meehan]

I poped of the floor drain in my basement because i started getting water in the basement a few days ago. It appears that water came up from there......i found what appeard to be toilet paper that had come up through the drain not to mention some other weird stuff i couldnt identify.

Would the city doing maintenence or somthing...cause this? I havent had this happen in the 3 years ive been living here. IM not sure what to do. I have tried to contact the city but havent gotten a response to my questions yet.

it is making a damn mess to say the least. It appears to be clean water......not black or anything. I tried flushing and turning all all the water to the faucets everywhere and it didnt make anything come up throught he drain........

Not sure where to start. If it was tree roots a clogged drain i would notice water come up it when i did the aboved mentioned things but i dont see the little bit of water i see down the drain rising at all during any of this.

It has me more than concerned......

any ideas?

[Joseph Meehan]

...

I should point out that using a cold water pipe is not a good idea because it may not be a good ground due to a number of reasons like maybe someone using a length of plastic pipe or some other reason and then if you have an fault in the dryer, it may make you kitchen sink hot. Very bad idea. I also believe it is against modern codes.

[hallerb]

all service entrances are bonded to ground rods and cold water pipe system.

its interesting to note this could result in a electrical powered water system

[Beachcomber]

The code for Dryers and Ranges was changed during WWII to allow 3 wire instead of 4 wires to save copper for the war effort. Within recent years it has changed back because people were getting shocks from dryers.

The problem with the 3 wire system is that the neutral (which is a current carrying conductor in a dryer) is also being used as a safety ground. Most dryer motors run on 120 V. even though the heating elements are 240 V. I believe the dryer light also runs on 120 V.

In an ideal world, the neutral is supposed to be at ground potential, but there are all sorts of reasons why this may not be true. You can have bad connections, or the overall ground system of the house may be marginal.

To fix this properly, you would need to run a new line with two hots, an isolated neutral, and a ground and install a four wire receptacle for the dryer.

Dryer cords come in 3 wire and 4 wire models and the code has "grandfathered" existing 3-wire installations.

Since you are one of the ones actually getting shocked by your installation, it may be a good idea to do the full fix.

Beachcomber

[Beachcomber]

That hokey "at least" is a code violation. The only point where ground and neutral are allowed to be connected are in your main service panel. The "ground" is never supposed to carry continuous current, only fault current.

Beachcomber

[Mark Lloyd]

Maybe you misunderstood. I was talking about the ground connection, which will be completely separate from neutral.

[Doug Miller]

I think you misunderstand. In your 3-wire dryer, the case is connected to the neutral. Running a wire from the case to a ground means that you've cross-connected neutral and ground.

[Beachcomber]

Absolutely right Doug! If you do it that way you will have issues with the 3-wire vs. the 4-wire plugs. Think about it for a while! That Safety Ground is supposed to come to the 4 wire plug. That is the only place it is supposed to go. If you've got the 4 wire receptacle and it is grounded, then the Neutral is properly lifted and no longer serves as the case safety ground.

What you are talking about is a hard-wire non-standard installation. Maybe it will work, maybe not... If you house burns down, your insurance might not pay if they discover your "non-code" compliant installation. If you sell your house along with the laundry equipment to a new owner, they are not going to have a clue what you did and you place them in danger also.

Beachcomber

[Mark]

A 3 prong dryer meets code and the neutral is connected to the case...thats the root cause of the problem, they never should have allowed that, but they did and there are many dryers out there like that and IMO it is unsafe. ....

IMO it is unsafe because an OPEN neutral fault can put dangerous voltage on the dryer case. So even though it meets code it is unsafe ...that is the reason for the so called hard wired ground.....

I don't see how connecting the CASE of an appliance to GROUND can be considered a problem, if anything it only makes the situation safer, the problem is that neutral is also connected to the case which is what the code stupidly allowed...

Mabe the right answer is to modify the dryer to disconnect neutral from the case and then run a seperate ground for the case.

I'm curious, has there ever been a intance of a person electrocuted due to an open neutral in a 3 prong appliance like this?

Mark

.

Mark

[Tom Horne, Electrician]

If you want to add an Equipment Grounding Conductor (EGC) to the dryer circuit you will need to run a fourth conductor in that circuit. If you try to use an EGC from another circuit then that EGC will not be large enough to cause the dryer circuits Over Current Protective Device (OCPD) to open quickly and you risk cross connecting the dryer circuits neutral to the laundry receptacle circuits EGC. That would cause neutral current to divide over the two parallel paths and it could raise the touch potential of the laundry equipment to dangerous levels.

[Doug Miller]

Well, that's a bit overblown IMO -- the risk from this practice isn't fire, but electrocution.

[Chris Lewis]

According to Pop :

Up until a few years ago, the US NEC permitted stoves and dryers to be connected using three wire connections. Two hots, and a third wire that acts as _both_ a neutral (for 120V loads like clocks and 120V accessory outlets) and for bonding the frame to ground.

Canadian CEC hasn't permitted this for at least 30 years.

US NEC has changed so that it requires 4 wire circuits just like Canadian CEC does. The difference being that the NEC has more "grandfathering" than the CEC does.

In CEC, when you install a new stove or dryer, you must bring existing circuits up to current spec. In NEC, you only have to bring existing circuits up to current spec if you're changing the circuit.

You can't buy a 3 wire cordset in Canada (I don't think we _ever_ required 3 wire outlets. It went directly from 4 wire direct connect to 4 wire outlets). You still can in the US.

Yeah, I think the NEC permissivity was dumb too.

[Chris Lewis]

Ahem. Didn't you notice that I said I _did_ switch off the breaker?