Low voltage control of 240v appliance

Reply

  #1  
Old 01-24-17, 07:12 PM
Member
Thread Starter
Join Date: Jul 2014
Posts: 95
Received 0 Votes on 0 Posts
Low voltage control of 240v appliance

Hi - I am installing a dust collector in my shop that is 220v and 15 amp rated. Because the machine is located in a remote area I'd like to be able to turn it on and off using a low voltage circuit with multiple switches around the shop.

I plan to use a contactor with a 24v transformer that goes to the shop switches that will be run in parallel. When I close any of the switches the 24v circuit closes, the contactor fires, and my motor turns on. My motor is permanently mounted on the wall so i can hard wire it or install a 220v plug.

I'll put the contactor in it's own box and run the 220 line to that box. Then I'm thinking I put a regular light switch (220 rated) in another box so that I have a safety off and I can hard wire the motor to that switch.

Anyone see any code problems with what I am proposing?
 
Sponsored Links
  #2  
Old 01-24-17, 07:27 PM
chandler's Avatar
Banned. Rule And/Or Policy Violation
Join Date: Dec 2005
Location: USA
Posts: 39,967
Received 3 Votes on 3 Posts
May be easier and possibly cheaper to use one of these. https://www.woodcraft.com/products/i..._WgaAmwq8P8HAQ
 
  #3  
Old 01-24-17, 07:32 PM
Tolyn Ironhand's Avatar
Group Moderator
Join Date: Nov 2007
Location: Twin Cities, MN
Posts: 13,057
Received 73 Votes on 65 Posts
FYI - voltages in the US are 120/240.

If you hard wire it code requires a disconnect at the motor. If it is connected with a cord and plug the cord can act as a disconnect.

I see no issues with your plan. Just make sure that any wiring inside the box with the contactor must be rated for the voltages inside that box. So, even the low voltage wire needs to be rated for 300 volts or more that is inside the contactor box.

Suggestion: I recommend using 3 ways (single pole double throw SPDT) and 4 way (Double pole double throw DPDT) switches. That way you can turn the collector on or off at any location.
 
  #4  
Old 01-24-17, 07:59 PM
Member
Thread Starter
Join Date: Jul 2014
Posts: 95
Received 0 Votes on 0 Posts
Thanks both !

I'm considering the woodcraft option but $20 vs $80 and I may have more "automation" options down the road with the wired version.

Can a regular light switch act as the "disconnect". And the motor has a switch on it - still need a disconnect then?
 
  #5  
Old 01-24-17, 09:25 PM
PJmax's Avatar
Group Moderator
Join Date: Oct 2012
Location: Northern NJ - USA
Posts: 54,598
Received 514 Votes on 484 Posts
Can a regular light switch act as the "disconnect". And the motor has a switch on it - still need a disconnect then?
No and yes... since the motor is 240v you can either use a two pole switch or an A/C service disconnect. Both legs of service must be open before it gets to the motor.

A switch like this is what I'd recommend.
It's rated at 30A which is higher than you need but is of pretty good quality.
Leviton 30 Amp Industrial Double Pole Switch, White-R62-03032-2WS - The Home Depot

You can use an A/C contactor as your relay. Available in one or two pole and are rated for 30A.
 
Reply

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are Off
Refbacks are Off


Thread Tools
Search this Thread
 
Ask a Question
Question Title:
Description:
Your question will be posted in: