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I would use this type of safety switch for your application: https://www.eaton.com/us/en-us/cata...ols-systems/double-throw-safety-switches.html
Ted
Ted
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Double 220 plug in for mill and grinder
- Thread starter Brett
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I have to say it sounds like you're making it too complicated with the switch IMHO. Since you're using an extension cord and not hard wiring anything into your panel it shouldn't be any kind of a code violation to have two outlets at the end of your cord. Since you won't be using both tools at the same time you shouldn't be drawing any more power than either tool can use, rate the wire for max amp draw of one tool and use an appropriate breaker on that circuit and you should be fine.
I'm familiar with the Blue Sea stuff from my marine electrical training, it's top notch and would totally recommend it if you needed a switch. Also familiar with transfer switches from my standby generator days and they would do the job too. I would not recommend the cheap Chinese switch from Amazon just on principle, this isn't the kind of application to try and save money on.
But, I don't really see any need for a switch at all. The VFD will only draw any significant amperage when it's running your grinder motor, otherwise it's just using line voltage to power the control board. If you really want to get fancy do like I did and put a sub-panel at the end of your extension cord and use regular breakers but that's just an extra expense. Spend the money on tools instead
Cheers,
John
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I just re-read your first post- now I understand- but- your VFD must have a power switch or standby mode of some kind, does it not? As John mentioned above, in standby it should not need to be disconnected from the power line, since it draws only a tiny current. But yes, you can add a main switch for it if you want to turn it off completely. So you really just want to build a split outlet with a switch on one side for the VFD- I assume your mill has it's own power switch
The VFD doesn’t have a power off switch. When it is plug in it is on and the fan is running too which is why I don’t want to leave it plugged in. The mill is kind of the same way. When it is plugged in the light on the mill is on showing power going to the mill. Probably not a big to leave that on since it’s just a power light but my ideal plan would be this. Use a splitter at the extension cord for the ceiling. Plug in both machines but have some kind of inline switch on each machine plug wire so the power could be completely cut off from the machine. Something similar to this.
I’m having trouble finding an in-line cord switch that is 250v 20 amp though. Not sure what to do. May just be stuck plugging and unplugging the machines.
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- Apr 30, 2015
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I'm sure you can find a beefy enough switch- keep looking
might be some $
You could always wire up a contactor and a light duty switch to do the job
might be some $
You could always wire up a contactor and a light duty switch to do the job
Simply put a 30A DPST wall switch in the circuit. You can put it on the feed to both items or just put it in series with either one or both. I have two switches at the mill . One is the switch above (20A) to power the mill. The other is the standard SPST wall switch to power all the 110V outlets and DRO. I flip both on to use mill and both off when I walk away. Been that way for a couple of years. I also wired the wood lathe VFD that way for wife. Been that way for about a year. If the switch is not available at big box store, go to electrical supplier. Around $10 from memory. Also using this on air compressor contactor. Kills power to both sides of contactor and that also kills power to contactor coil.
Here is HD # for 30A
Model # R62-03032-2WS
Store SKU #589535
Store SO SKU #162677
Here is HD # for 30A
Model # R62-03032-2WS
Store SKU #589535
Store SO SKU #162677
- Joined
- Feb 13, 2017
- Messages
- 2,138
If the plug(s) to be loaded are difficult to get to, as in over, under, behind, or otherwise obstructed, I concur with your general idea. The difficulty arises with the "switch" carrying load current will require running either large wire some distance or the switch being also located also in a difficult position.
I offer two possible solutions, the first of which is an extension cord of suitable size brought out to an easy to reach location, with a switch (if desired) located in the enclosure at the end of the extension. It would make things easier to plug or un-plug with this remote so the need for a switch would be minimized. A little extra length on this extension would allow it to be moved to the desired machine.
The second, more complex, solution is to use Air Conditioner relays mounted at or near the existing source. They are usually low voltage relays, 24 volt coils. While they are not high current(>20A) rated, they are cheap and easy to acquire and replace when needed. A low power switch that would provide mutually exclusive operation could then be mounted at a convienent location. Since it is a low voltage, low current operation it would be below most codes concern. An old small extension cord with the plugs cut off would be all that was required. 3 conductor, of course~~~ for portable cable, the NEC allows the green wire to be current carrying.
For such an operation, a "single pole, double throw, center off" (SPDT-CO, ON-OFF-ON, or 3 position) switch would suffice. I have numerous such switches on hand, they are very common with my models. They are available at most automotive suppliers. Or if you were a stickler for better quality devices, most any electrical or electronics supplier. We're talking a couple of dollars for best case devices.
In either case, the final call is yours to make. My suggestions are just that, suggestions. I have been "finagling" similar setups for years and having been an electrician for well over 60 years (50 professionally) and am knowledgable of the safety concerns involved. Safety is the most important part of such an attempt.
I offer two possible solutions, the first of which is an extension cord of suitable size brought out to an easy to reach location, with a switch (if desired) located in the enclosure at the end of the extension. It would make things easier to plug or un-plug with this remote so the need for a switch would be minimized. A little extra length on this extension would allow it to be moved to the desired machine.
The second, more complex, solution is to use Air Conditioner relays mounted at or near the existing source. They are usually low voltage relays, 24 volt coils. While they are not high current(>20A) rated, they are cheap and easy to acquire and replace when needed. A low power switch that would provide mutually exclusive operation could then be mounted at a convienent location. Since it is a low voltage, low current operation it would be below most codes concern. An old small extension cord with the plugs cut off would be all that was required. 3 conductor, of course~~~ for portable cable, the NEC allows the green wire to be current carrying.
For such an operation, a "single pole, double throw, center off" (SPDT-CO, ON-OFF-ON, or 3 position) switch would suffice. I have numerous such switches on hand, they are very common with my models. They are available at most automotive suppliers. Or if you were a stickler for better quality devices, most any electrical or electronics supplier. We're talking a couple of dollars for best case devices.
In either case, the final call is yours to make. My suggestions are just that, suggestions. I have been "finagling" similar setups for years and having been an electrician for well over 60 years (50 professionally) and am knowledgable of the safety concerns involved. Safety is the most important part of such an attempt.
Bill Hudson
Thanks again everyone for the tips and suggestion so far. I still haven't found an inline switch that has a high enough amp rating. What if I just did something like the drawing below.
I would have the wire from the ceiling come down into a box. Then splice the wires and hook up two 30A DPST switches. Connected to each separate switch are the outlets. Plug the mill in to one outlet and the grinder into the other. When I want to use one the machines flip the switch for the outlet that machine is plugged into. Let me know if I'm way off or if this is something that could work? Thanks in advance.
I would have the wire from the ceiling come down into a box. Then splice the wires and hook up two 30A DPST switches. Connected to each separate switch are the outlets. Plug the mill in to one outlet and the grinder into the other. When I want to use one the machines flip the switch for the outlet that machine is plugged into. Let me know if I'm way off or if this is something that could work? Thanks in advance.
You drew the picture with 110V wiring. In the old days, you could paint or tape the white wire "red" and get away with it. The electricians that I have worked with in the last couple of years said that is a no-no any more. You need Red/Black/Green for your set up. I do have the painted white wire in some mobile homes that use it for a hot feed. They are 30 years old. Portable cords are a different story.
If you are running new wire, consider going to 10/4, which is red/black/white/green. The white is not used for 220V. But you can grab either the red or black and make a 110V outlet in the same place. Example, red/white/green. I have a triple drop 220V/110V at the mill, wood lathe & drill press. I used black at the drill press and wood lathe and red at the mill for 110V outlets. I have my switches at the machine because it is more convenient for me. You can do it as you have drawn above. Electrically it does not matter. Pay attention to the length from breaker to machine. The guys are correct about voltage drop and maybe using relays and larger wire etc. The suggestion about low voltage relays and switch is good and I have done that in the past. It does add some complexity to the system. On new systems, I just went with the wall switch as the cheapest way out.
If you are running new wire, consider going to 10/4, which is red/black/white/green. The white is not used for 220V. But you can grab either the red or black and make a 110V outlet in the same place. Example, red/white/green. I have a triple drop 220V/110V at the mill, wood lathe & drill press. I used black at the drill press and wood lathe and red at the mill for 110V outlets. I have my switches at the machine because it is more convenient for me. You can do it as you have drawn above. Electrically it does not matter. Pay attention to the length from breaker to machine. The guys are correct about voltage drop and maybe using relays and larger wire etc. The suggestion about low voltage relays and switch is good and I have done that in the past. It does add some complexity to the system. On new systems, I just went with the wall switch as the cheapest way out.
They make a standard lught switch that is DPSP double polarity so good for 240 volt switching rated for 20 amps.
Box store has them.
Get name brand unit.
Since it is on line side of VFD it is not acting as motor starter so contacts will be fine.
Photos if ours.
Light switch is the main power.
We added a 240 vac neon pilot to the drum switch so we know power is on
The meter connects to the VFD 0-20 ma signal line that shows frequency or load, set to show frequency and the knob sets speed.
Added foot brake bar as drum switch over the Chuck and foot switch stops lathe
All mounts in subframe.
The light switch works fine for 5 years now.
Sent from my SAMSUNG-SM-G930A using Tapatalk
Box store has them.
Get name brand unit.
Since it is on line side of VFD it is not acting as motor starter so contacts will be fine.
Photos if ours.
Light switch is the main power.
We added a 240 vac neon pilot to the drum switch so we know power is on
The meter connects to the VFD 0-20 ma signal line that shows frequency or load, set to show frequency and the knob sets speed.
Added foot brake bar as drum switch over the Chuck and foot switch stops lathe
All mounts in subframe.
The light switch works fine for 5 years now.
Sent from my SAMSUNG-SM-G930A using Tapatalk