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IndustryArena Forum > CNC Electronics > CNC Machine Related Electronics > Tie 220v VFD into dryer line - with a switch?
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  1. #1
    Join Date
    Oct 2018
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    20

    Tie 220v VFD into dryer line - with a switch?

    Hello, I've setup my CNC router in the basement. The clothes dryer and service panel are in the utility room directly above the router table and it's roughly in between them. The dryer supply runs between the joists directly overhead. I was thinking of tying into this circuit, adding a smaller breaker for the VFD (typical 220v/2.2kw) and a switch so the dryer isn't inadvertently used while the CNC is running. Something like an aux generator transfer switch with integrated breaker, but in reverse. I have the ability to run a dedicated circuit, but I'd really rather not if there's a perfectly good breaker already in the panel (dryer) not being used 90% of the time.

    Are there better ways to do this? Or has anyone done such a thing and can offer tips? Thanks!

  2. #2
    Join Date
    Dec 2013
    Posts
    5717

    Re: Tie 220v VFD into dryer line - with a switch?

    That seems overly complicated for what you need. Why not just tap into the dryer power for the router, then unplug the dryer when using the router. That would prevent inadvertent use of the dryer.
    Jim Dawson
    Sandy, Oregon, USA

  3. #3
    Join Date
    Dec 2003
    Posts
    24216

    Re: Tie 220v VFD into dryer line - with a switch?

    You could also plug in a non-wired dryer plug top into the outlet to reinforce that the plug is in use.
    Al.
    CNC, Mechatronics Integration and Custom Machine Design

    “Logic will get you from A to B. Imagination will take you everywhere.”
    Albert E.

  4. #4
    Join Date
    Jan 2005
    Posts
    15362

    Re: Tie 220v VFD into dryer line - with a switch?

    Quote Originally Posted by ddurbs21 View Post
    Hello, I've setup my CNC router in the basement. The clothes dryer and service panel are in the utility room directly above the router table and it's roughly in between them. The dryer supply runs between the joists directly overhead. I was thinking of tying into this circuit, adding a smaller breaker for the VFD (typical 220v/2.2kw) and a switch so the dryer isn't inadvertently used while the CNC is running. Something like an aux generator transfer switch with integrated breaker, but in reverse. I have the ability to run a dedicated circuit, but I'd really rather not if there's a perfectly good breaker already in the panel (dryer) not being used 90% of the time.

    Are there better ways to do this? Or has anyone done such a thing and can offer tips? Thanks!
    Depends how many amps the Dryer Breaker is, if you can use that circuit, 2.2Kw spindle needs a minimum of 25amp supply so you are looking at a 30A Breaker and wiring to match
    Mactec54

  5. #5
    Join Date
    Jan 2005
    Posts
    1943

    Re: Tie 220v VFD into dryer line - with a switch?

    Seems dumb to me to not run a new circuit if the service panel is directly above where the router is going. You'll spend more money on a "transfer switch" than you would just buying a CB and running a new circuit.

  6. #6
    Join Date
    Sep 2005
    Posts
    1740

    Re: Tie 220v VFD into dryer line - with a switch?

    Quote Originally Posted by 109jb View Post
    Seems dumb to me to not run a new circuit if the service panel is directly above where the router is going. You'll spend more money on a "transfer switch" than you would just buying a CB and running a new circuit.
    Well he does not really need a transfer switch. Most dryer outlets are 30 amp with #10 wire, he could set a J box and T off adding another outlet, splicing into the the #10 wire (inside the J box) however would involve split bolt connectors, tape or the like. A pain in the rear and the price of doing all that would not be cheap. Its safe however because the 30 amp breaker is protecting the circuit.

    But... I would just run a new circuit from the panel.
    Retired Master Electrician, HVAC/R Commercial. FLA Saturn 2 4x4 CNC Router Mach4 Kimber 1911 45ACP

  7. #7
    Join Date
    Oct 2018
    Posts
    20

    Re: Tie 220v VFD into dryer line - with a switch?

    The reason for a switch is so nobody else in the house runs the dryer while I'm using the circuit. It's easy to ask someone not to, but that doesn't always work. I also don't want to have to go between the basement and the utility room on the main floor to plug/unplug something every time I want to cut out a small piece. It's a hobby machine and it typically gets used for short periods but sometimes throughout the day while I test parts. I'd rather not run a new circuit because of the location of the box and the difficulty getting wires up there - four 2x4s and insulation between the basement and the box inside the exterior wall. I know because I did it once last year to run a new circuit to feed my workbench and it was a bear, and I've done it many times at previous houses without much trouble. If I were to do it over I would cut out some drywall then patch and paint when it's over. Nobody likes patching or painting. But I have my eye on a new tig welder and for aluminum I'll need more power so if I go that route it may require a new circuit so I'm not competing with dryer time for two tools.

    The dryer circuit is indeed 30A.

  8. #8
    Join Date
    Sep 2005
    Posts
    1740

    Re: Tie 220v VFD into dryer line - with a switch?

    Like I said in my post, its going to be less hassle and expense in the long run just to run another circuit.. But do as you wish.
    Retired Master Electrician, HVAC/R Commercial. FLA Saturn 2 4x4 CNC Router Mach4 Kimber 1911 45ACP

  9. #9
    Join Date
    Jan 2005
    Posts
    1943

    Re: Tie 220v VFD into dryer line - with a switch?

    Not sure where you are located, but you need to check code requirements. What you propose would not fly where I live. It would be considered a code violation regardless of whether it would work because a dryer circuit is required to be a dedicated circuit if installed.

    Insulation, drywall and a few studs is a poor excuse for not doing it right. I'd much rather have to patch some drywall and have a proper circuit. In the end it is your house, but I wouldn't hack mine like that.

  10. #10
    Join Date
    Oct 2018
    Posts
    20

    Re: Tie 220v VFD into dryer line - with a switch?

    Thanks guys, there was lots of good info to chew on here. It looks like there's a clear consensus for a new circuit. I haven't checked if code requires my dryer to exist on a dedicated circuit but I don't have to as I now realize my idea is just not the best way to go about it. The final nail in the coffin was after I researched the TIG welder I want and it specifies 44A at full power. So now I want to put in a full 50A circuit for future possibilities. I may have an electrician come out for something like that. Maybe it's a good time to think about a sub-panel in the basement to deal with future build-out rather than making swiss cheese out of my wall studs. The basement only has two 120V/20A circuits - one for lighting and one for 4 single-gang boxes. That outlet circuit hosts the water softener and HVAC condensation pump - and now my motorcycle battery tenders and drill battery chargers. There's going to be significant additions to safely run standard home workshop tools and probably more lighting as well. It's overwhelming when you just want to get it done and other obligations make it a much lower priority.

  11. #11
    Join Date
    Dec 2013
    Posts
    5717

    Re: Tie 220v VFD into dryer line - with a switch?

    Just a design consideration, I would normally surface mount a sub panel for shop use. Then use plastic conduit on the surface, makes wiring easy and is easy to add circuits and make changes later.
    Jim Dawson
    Sandy, Oregon, USA

  12. #12
    Join Date
    Oct 2018
    Posts
    20

    Re: Tie 220v VFD into dryer line - with a switch?

    Hi Jim, thanks for the tip. The basement is a walk-out due to the slope so half is above ground. It's all block with no wall covering. I may put up a single wall to cut it in half and keep the dust and curse words in the shop section where they belong. ha

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