fourth wire to the saw

[Andre Cormier]

Just finishing up the wiring on my new Bandsaw and there is a second ground point on the machine to ground the frame. Do you guys run a second ground to your machinery as an added level of protection or are 2 loads and a ground sufficient?. (3 vs 4 wires 220v)

thanks

[Jon van der Linden]

To be sure what you should do with your situation you should contact customer service for your brand of saw. It's difficult to know what you need without specific information.

Usually when I think of four terminals I think 3 phase power. It just sounds a little odd to have a connection for the frame itself that requires a separate hookup. After all, If the frame needed grounding, it should already be connected to the grounding terminal.

Electricity is not your friend, so it's always good to double check things.

[Scott T Smith]

4 wire 240VAC single phase circuits are usually comprised of two hots, a neutral and a ground, not two grounds.

Ditto Jon's comments about contacting CS for your equipment; having two separate ground leads is definitely not the norm.

[Andre Cormier]

4 wire 240VAC single phase circuits are usually comprised of two hots, a neutral and a ground, not two grounds.

Ditto Jon's comments about contacting CS for your equipment; having two separate ground leads is definitely not the norm.

Yes I think my best bet is to call CS on Monday. The reason I brought this up is that I read someplace, maybe on this forum that some people ran 4 wires to their equipment and converted the neutral to ground and attached it to the frame as additional safety. Like someone said the ground is probably already attached to the frame someplace but the Fact that there is a labeled ground point on the frame has me scratching my head.

Thanks for the replies

[Mitchell Andrus]

Can you not find the wiring schematic on-line on the mfgr's site?
.

[John Coloccia]

Yes I think my best bet is to call CS on Monday. The reason I brought this up is that I read someplace, maybe on this forum that some people ran 4 wires to their equipment and converted the neutral to ground and attached it to the frame as additional safety. Like someone said the ground is probably already attached to the frame someplace but the Fact that there is a labeled ground point on the frame has me scratching my head.

Thanks for the replies

That's a very bad idea. If the neutral where to ever come disconnected at the subpanel, for whatever reason, every machine that was wired like this would suddenly have current flowing through it's frame as the electricity found it's way through the neutral, to the machine, and then back through the ground conductor. Maybe they really meant they were running two grounds to the machine?

What brand/model bandsaw? Can you post pictures? I'm sure you'll get it straightened out on monday with CS, but now I'm curious to know what you're seeing! :)

[Mike Cruz]

Um, Mitchell, don't look now...really...don't look, but....um...there's a pumpkin on your head. :eek:

[Rick Christopherson]

Yes I think my best bet is to call CS on Monday. If it is a chassis ground, then it is a chassis ground. There is no need to confirm this.

However, ground and neutral are not the same, so anyone that has led you to this conclusion is not someone you should be taking advise from.

[Andre Cormier]

Rick, what is the purpose of a chassis ground.

I got the saw all wired and works fine (wired the normal way 2 hots and a ground). Sorry I didn't have any time to post pictures of what I was seeing.

[Rick Christopherson]

In a nutshell, the purpose of the chassis ground is to remove any stray voltage from the chassis. This can occur from the obvious cause of a short between a live conductor and the chassis, but it can also occur from inductive/capacitive coupling. This is where a nearby wire can induce voltage in another material without actually touching.

The ground wire bleeds off this voltage. In the case of a short, the current will be very high and the circuit breaker will trip. In the case of induced voltage, there is very little current and the voltage is just bled off to ground. It's a lot more complicated than I can described here in a posting, but if you are still curious, read Electricity in the Woodshop (http://www.waterfront-woods.com/Articles/Electricity/electricity.htm).