Dryer outlet grounding


Old 09-05-09, 03:31 PM
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Dryer outlet grounding

I need to replace my old dryer wall mount box outlet because it is ancient and rusty. This is the 3 prong with a L shape style. The conduit has white, red and black wires, in addition to a bare copper ground, that was connected with a screw into the old metal box. However, the new outlet says "3-pole, 3-wire non-grounding" and it says to "connect only to non-grounding circuits." But aren't I safer if I connect my ground wire to the metal box? There is a little hole in the top of the box I could stick it into just to make metal contact.
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Old 09-05-09, 04:05 PM
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If you want an even safer install you can install a 4 wire grounding receptacle and cord. You would need to remove a bonding jumper from the wiring compartment of the dryer, but this is a simple thing to do, especially while changing the cordset.
Old 09-05-09, 05:03 PM
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Is your metal box grounded, though? If no emt or bx cable from metal box to panel box, then you could cause box to become energized under right conditions(say if machine got a short). However, if that were to happen, so would the machine itself become live. So pick your poison I guess as to what could happen if you touched either while barefooted on damp concrete or on wet linoleum from washing machine water on floor, let's say. Or if you touched the grounded washing at the same time as touching the dryer, or your metal box with your proposed ground wire from the dryer hooked to it.

The idea of the 3 wires in the dryer is to give you 2 hot wires so you get 240, and then the white wire is for the neutral for the motor to run on 120. Bonding of the chassis to the neutral, at the terminal connection area behind the dryer, will send any possible short down that neutral wire, to reduce any risk of you taking a full hit of electric in case of a short.

As already pointed out, the newer 4-wire system is actually the new code now, as it is safer, with the neutral and ground being seperated. Technically the way 3 wire is, the electric current can run thru the chasis of the machine at all times, short or no short, since the ground path and neutral are shared(via bonding strap) right in the machine.

But wirh the 4-wire system, neutral and ground are not shared at the machine. You would have to have a short in order for you to share the ground path, while in bare feet on wet surface.
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