Question for you folks...

The wife is getting a new washer & dryer. The dryer's going to be electric (shock - I've had gas dryers since I was a wee tot), and it is suggested in the manual to install a 4-Wire receptacle .


I know that the "hots" go to each of the straight blades, the neutral (white) goes to the "L", and the ground (green) goes to the, well, ground shaped (D) terminal.

My question is - in a conduit system do you need to run an actual grounding wire all the way back to the panel, or can your connect a "jumper" from the ground terminal to the grounding terminal in the junction box? If the conduit is intact, is it allowed to act as the grounding conductor, or is conduit grounding only reserved for accidental fault purposes?

(Gimme a break - I've never had to wire one of these before - they've all been 10-30's.)

It's not that long a run to the panel (maybe 30'), so I'm going to run the grounding wire all the way anyway. I'm just looking for feedback.

Thanks,

Doug

you can do either way as long the pipe is emt but i rather run real grounding wire from breaker box to the junction box from there you have to make a pigtail i know it is little tough to make a pigtail with #10 wire but it can be done .

this is my most common pratice to run full 4 wires even thru if run in emt i still do that because for safety reason if the emt do " break " you still have grounding protection there

Merci. Marc

p.s. double check your dryer connection on back of dryer where the electrical connection you will see a jumper band there take it off and run like true 4 wire [ most dryer and stove dont provide the plug anymore so watch out with this one ]

[This message has been edited by frenchelectrican (edited 10-19-2005).]

I prefer a short tap of #12 THHN solid, as against #10. The extra voltage drop over merely 8" is not going to cook anything -- and is code compliant.

Other than that I'm with the frenchman.

If the cost of wire keeps going up, pretty soon I bet we will start seeing a return to using the emt as the sole grounding method for a lot of the pennywise out there.

No, it's not code compliant. The EGC has to be a #10. See Table 250.122.

Peter

I'm not so sure about #10 being required for the pigtail to the box. After all, it was only with the 2005 code that relying on the contact between the device strap and the box for grounding was restricted to surface-mount boxes.

I think it is more important to remember to open up the back of the dryer and remove the case/ neutral jumper that is installed when you use a four-prong plug.

Read 250.146 and then decide if you will need to put a jumper to the box. Some of these receptacle ground terminals are not fastened to the strap on the larger ampere sizes. I'd use a continuity meter and check between the strap and the grounding terminal of the receptacle.

[This message has been edited by George Little (edited 10-19-2005).]

Good points, George!

+1 for removing the grounding strap... it's mentioned quite prominently in the install guide.

Thanks to everybody for their $0.02... it's nice to be able to second guess yourself now and again. I owe you guys a beer!

250.122

(A) General. Copper, aluminum, or copper-clad aluminum equipment grounding conductors of the wire type shall not be smaller than shown in Table 250.122 but shall not be required to be larger than the circuit conductors supplying the equipment.....

Table 210.24: (partial)
50A... Circuit Wires... #6...Taps #12 OCPD 50A

I argue that if the EGC is sized identically to the hots that 250.122 is met in as much as the EGC taps are identical to the hot taps.

You seem to be using tap rules to justify undersizing the egc.

Without getting into the issue of 'are taps allowed in this circuit', _if_ a tap were to be allowed I could see your point that the egc could be reduced in size to match the size of the taps.

For example, if one had a 50A cooking appliance circuit feeding a 20A cooktop and a 30A oven, I could see your justification used to run a 12ga EGC to the cooktop along with the 12ga supply conductors.

But in this case, we don't have a tap. We have the full 10ga 30A supply conductors feeding a receptacle. The egc must be sized for the 30A circuit, as per table 250.122.

-Jon

Any EGC is always based on Table 250.122.

If you look at Table 250.122 you will see the following wording.


There is no code section that allows reducing the EGC run with tap conductors other than 250.122(A) which tells us the EGC is not required to be larger than the ungrounded conductors.