Shopbot PRS 48x96 Acorn / Clearpath Conversion

[paulwall]

Appreciate the clarification, but I'm only running 240v and never separating the poles (no use of 120 throughout the entire box).

My monitor and PC PSU are 240v rated for hot/hot/ground as far as I know.

[paulwall]

Unless devices listed at 240V are setup for 1 hot 240v and a neutral, I can't think of any other reason why this setup wouldn't work.

Edit: Maybe that's where I've gone wrong.

[tkbot47]

Years ago, when houses just had 2 prong outlets only, 120V used to come in with only 2 wires, hot and return, and 240V was 3 wire - no ground. Many years ago the national electric code changed to require a separate ground return only joined to neutral at the main breaker box or meter box, as tblough said, for safety in case a device shorts out to ground, instead of a floating chassis or box that would then sit at full voltage, and you would be the short to ground if you touched the box. Separate ground has been the national electrical code since the late sixties, I believe.

You need one of the two following:

1. 240V 1ph 4 wire into your box. Run the two hots to your VFD contactor for 240V 1ph, and take 110V 1ph from between one of the 240V legs and neutral. I don't recommend this because is unevenly loads the 240 legs, and I'm not sure what that would do to VFD performance.

2. 2 separate feeds to your box. One 3 wire 240V 1ph to feed just the contactor for the VFD. No neutral required for VFD's I'm familiar with. One 3 wire 120V 1ph feed (20A for good measure) to feed your box circuits, power supplies, motors, etc., run through an EMI filtered surge protector.

The tools and appliances you wired were probably 240V only. If dryers, for instance, had 110V control circuits, you would have needed a 4 wire circuit, if not, a 3 wire would have been good enough in the day.

[tkbot47]

Appreciate the clarification, but I'm only running 240v and never separating the poles (no use of 120 throughout the entire box).

My monitor and PC PSU are 240v rated for hot/hot/ground as far as I know.

Paul, OK, I had asked about that in my first response. You seem to be correctly wired for running all components at 240V in that case. You threw us off with the red and black wires labeled as 110V hot. Those two wires would measure 110V between them and ground, but that is not acceptable wiring, and they would also be 180 degrees out of phase.
If you're running everything at 240V, make sure everything is rated for 240V at current, and don't need jumpers changed, etc. to function properly. I know something has to be done with the AC wire connection for the IPC-5 power supply, and there might be switches on the other power supplies to select input voltage.

[paulwall]

You're right. The WM RD35B, the Din 24v PSU, and the 2 computer PSUs are all 240v capable, but it has to come in on a single pole (like European 240v plugs).

The IPC-5 (yes slightly different wiring configuration) and VFD are 240 (120v hot, 120v hot, ground) capable.

In that case Tom I'm going to have to go with the 2 separate feeds, or a big expensive transformer, but the 2 feeds sounds easier and cheaper. Thanks guys!! I'll rework the diagram.

[paulwall]

So I'm getting some conflicting information. I made a post with the very question about whether you can power DC PSUs that are rated for 240v with hot/hot/ground over at the reddit electrician sub-reddit, and the consensus seems to be that it's just fine. In fact one guy wired his Dell PSU for his laptop straight to a hot/hot/ground connection with no problem.



Edit: After doing some more reading and youtubing, I think my power method as shown is fine so long as all PSUs are rated for 240v and nothing requires 120v, which it currently doesn't.

A neutral is only needed when you have a single 120v hot leg so you have a return because you're center tapping (cutting in half) the 240v secondary winding at the transformer on the street. The 240v hot/hot essentially has its own neutral because it's a complete circuit. In both cases green is still ground, and still not energized. I'm going to do some safe testing of a computer PSU tomorrow on a 240 hot/hot/ground setup and see how that goes.

[martyscncgarage]

If the power supply is rated 120-240 its fine. Two hots and a ground. Be sure the power supply does not have a switch you need to flip between 120-240VAC. Most newer ones autosense.

[paulwall]

If the power supply is rated 120-240 its fine. Two hots and a ground. Be sure the power supply does not have a switch you need to flip between 120-240VAC. Most newer ones autosense.

I wish there were a 'like' or thumbs-up feature on this forum. Thanks Marty!

[martyscncgarage]

[paulwall]

i like it!

Also wanted to post a UL best practice for other newbs like myself for circuit breaker protection that I found after a few days of searching - I'm sure there are plenty of folks who know this like the back of their hand, but it was big news to me!

Aside from the UL 489 and 1077 distinction, calculating the feeder circuit breaker rating should be done the following way:

Take the protection rating of the largest branch breaker, and add it to the max current rating of each of your branch loads. This was posted up in a PDF by ajhurst.com and can be found http://www.ajhurst.com/uploads/general/ ... ov2014.pdf