Question for the electricians (NH)

[wylee]

I'm buying a new washer and dryer and moving them out of my basement. The current dryer is on a 10/2 line and has a 3 prong plug. I want the new plug upstairs to be the new four prong type, but the main panel does not have separate neutral and ground buses.

I know the ideal solution would be to upgrade to a 200 amp main with separate buses, but can I legally run a new 10/3 line and attach the neutral and ground wires in the main panel to the same bus?

Any other ideas of how to proceed without upgrading the main panel?

[burnham]

What you propose is the way I do it every day, there is nothing wrong with the ground and neutral being terminated at the same bus of the main panel. Just don't put them under the same screw. It would be different only if you were going to a sub-panel, or in a trailer. The 10/3 four prong setup is to give you an insulated neutral, and a totally separate path for the ground wire. When you connect the four-wire cord to the appliance, there should be a small copper jumper that connects neutral and ground located behind the access panel. Remove that jumper, it's no longer necessary with 4 wires and leaving it installed defeats the purpose.

[wylee]

What you propose is the way I do it every day, there is nothing wrong with the ground and neutral being terminated at the same bus of the main panel. Just don't put them under the same screw. It would be different only if you were going to a sub-panel, or in a trailer. The 10/3 four prong setup is to give you an insulated neutral, and a totally separate path for the ground wire. When you connect the four-wire cord to the appliance, there should be a small copper jumper that connects neutral and ground located behind the access panel. Remove that jumper, it's no longer necessary with 4 wires and leaving it installed defeats the purpose.

Thanks!

[stoinkythepig]

Under normal circumstances, would any current flow in the 4th (neutral) wire in a 240 volt circuit? Thinking it's just another ground wire, in this application, and I can't fathom why it's even necessary. What's the purpose of it?

[wylee]

Under normal circumstances, would any current flow in the 4th (neutral) wire in a 240 volt circuit? Thinking it's just another ground wire, in this application, and I can't fathom why it's even necessary. What's the purpose of it?

The fourth wire is a ground only; if it's carrying current, there is a problem. The problem with the 3 wire setup is the neutral wire is not isulated and there is no ground. In theory the dryer cabinet could become energized with the three wire setup...I read an example of it happenning but can't remember the exact circumstances.

[ZX-12R]

Under normal circumstances, would any current flow in the 4th (neutral) wire in a 240 volt circuit? Thinking it's just another ground wire, in this application, and I can't fathom why it's even necessary. What's the purpose of it?

In a lot of dryers only the heating element requires 240V. The rest of the electrical items like the drum light, controls, and drive motor run off of ground referenced 120V lines. With 3 prong 240V outlets, the uninsulated ground wire acts as the return for the 120V components which defeats its purpose of being a non-energized safety connection. The 4 wire outlet gives you an insulated common to carry the 120V return load so the ground connection is not energized.

[stoinkythepig]

Ah, both explanations make sense. Cheers.

[KB]

Sounds like potugese to me.

KB

[ZX-12R]

Sounds like potugese to me.

KB

That's because I am Portuguese!

[KevinB]

In a lot of dryers only the heating element requires 240V. The rest of the electrical items like the drum light, controls, and drive motor run off of ground referenced 120V lines. With 3 prong 240V outlets, the uninsulated ground wire acts as the return for the 120V components which defeats its purpose of being a non-energized safety connection. The 4 wire outlet gives you an insulated common to carry the 120V return load so the ground connection is not energized.

So guess what would happen if you had a poor neutral/ground connection on a 3 wire system. Nothing, until you touch the dyer and then bingo you complete the circuit.

[Wishbone]

Black is the owwy wire

[KB]

Black is the owwy wire

That is the one that makes you speak portugese!!

KB

[wylee]

Black is the owwy wire

Black = ouch
Red = tickle - fuck! that's ouch too
Black + Red =