Double Throw Switch Hookup - Electrical - DIY Chatroom Home Improvement Forum
Advertisement


Go Back   DIY Chatroom Home Improvement Forum > Home Improvement > Electrical

CLICK HERE AND JOIN OUR COMMUNITY TODAY...IT'S FREE!

Like Tree9Likes
Reply
 
Thread Tools Search this Thread
Display Modes
Old 05-06-2020, 07:16 PM   #1
Newbie
 
Join Date: Apr 2013
Posts: 20
Rewards Points: 26
Default

Double throw switch hookup


Hi
I have 3 220 volt vats , basically a 220 volt hot water element which melts wax thatís on top of the water element. I only have room in my square D panel for two 20 amp breakers. I want to connect this double throw switch to supply two of my vats, one vat is only turned on every once in a while so want to turn off one vat and turn the other on as is needed. You can see in the panel the two 20 amp breakers that are off right now.
Can I get some guidance on how to wire this switch in?
Thanks
Lynn
Attached Thumbnails
Double throw switch hookup-f66effe0-0e01-4067-8a31-daa85fa7b8d4.jpeg   Double throw switch hookup-18a6b7c5-7701-47cf-8276-4776faaac4ad.jpeg   Double throw switch hookup-85c44c99-9557-43a3-a5d9-5d2681d23e2e.jpeg   Double throw switch hookup-baf814d7-fa6d-4772-a7f8-e254c3cb319f.jpeg   Double throw switch hookup-8d092710-0231-4a0a-905e-658b3ce920f7.jpeg  

Double throw switch hookup-0bcb3c32-3fa2-45c4-b2e9-ae5a37eb399f.jpeg  
Disisme is offline   Reply With Quote
Sponsored Links
Advertisement
 
Old 05-06-2020, 07:36 PM   #2
Member
 
Join Date: May 2018
Location: New York State
Posts: 1,063
Rewards Points: 2,120
Default

Re: Double throw switch hookup


I think what you are saying is that you want one of the vats (call it vat A) on one circuit breaker and the other two vats (call them B and C) on the second circuit breaker, and then use the switch to select either B or C. Is that correct?

If so, that switch is the wrong type of switch. It is a double pole switch, but it is not double throw, which is what you need so that in one position vat B will be on, and in the other vat C will be on.

Instead, you would use a switch like the Hubbell HBL1386I.

https://www.zoro.com/hubbell-wiring-...6i/i/G2517313/

Another option would be this switch from Bryant.

https://www.westwayelectricsupply.co...tr-off-wh.html
Disisme likes this.

Last edited by RAL238; 05-06-2020 at 07:53 PM.
RAL238 is online now   Reply With Quote
Sponsored Links
Advertisement
 
Old 05-06-2020, 08:37 PM   #3
Newbie
 
Join Date: Apr 2013
Posts: 20
Rewards Points: 26
Default

Re: Double throw switch hookup


Quote:
Originally Posted by RAL238 View Post
I think what you are saying is that you want one of the vats (call it vat A) on one circuit breaker and the other two vats (call them B and C) on the second circuit breaker, and then use the switch to select either B or C. Is that correct?

If so, that switch is the wrong type of switch. It is a double pole switch, but it is not double throw, which is what you need so that in one position vat B will be on, and in the other vat C will be on.

Instead, you would use a switch like the Hubbell HBL1386I.

https://www.zoro.com/hubbell-wiring-...6i/i/G2517313/

Another option would be this switch from Bryant.

https://www.westwayelectricsupply.co...tr-off-wh.html
Yes thatís exactly what Iím trying to say. Ok wrong switch, darn. Ok Iíll have to see about getting one of the other two options. How would I wire in a switch like those you suggest?
Disisme is offline   Reply With Quote
Sponsored Links
Advertisement
 
Old 05-06-2020, 08:47 PM   #4
Newbie
 
Join Date: Apr 2013
Posts: 20
Rewards Points: 26
Default

Re: Double throw switch hookup


What would be the difference with the switch I have and the two you suggest other than yours has a centre off position ? Do I need a centre off position ? Basically one or the other but not both needs to be on. I think that was the explanation I gave at the electrical place when he sold me the 20amp switch.
Attached Thumbnails
Double throw switch hookup-2ed44766-0875-4ea6-af9d-8f4b4efca973.png  
Disisme is offline   Reply With Quote
Old 05-06-2020, 09:05 PM   #5
Member
 
Join Date: May 2018
Location: New York State
Posts: 1,063
Rewards Points: 2,120
Default

Re: Double throw switch hookup


Quote:
Originally Posted by Disisme View Post
Yes thatís exactly what Iím trying to say. Ok wrong switch, darn. Ok Iíll have to see about getting one of the other two options. How would I wire in a switch like those you suggest?
Since you have a 240V circuit to power the vats, there are 2 hot wires in the cable, Line1 and Line2. From your photo of one of the vats, it looks like the wires coming in from the breaker are white and black. (In some cases, you could have black and red.)

The switch has two independent halves - think of it as two separate switches which are tied together.

The terminals for each half are grouped together on each side of the switch, with 3 different color screws - black, copper and brass.

The black screws are the "common" terminals and get connected to the incoming white and black wires from the circuit breaker.

Then, connect the black and white wires of a new cable to the two brass colored screws and connect the other end to vat 2. And take another new cable and connect the black and white wires to the copper colored screws and connect the other end to vat 3.

The switch also has a ground screw, which should be connected to the ground wires of all the cables. Use a pigtail to the switch and a wire nut to join the pigtail with the cable ground wires.


If you find wiring diagrams helpful, there is one here. Follow the wiring for the 2-pole version.

For the new cables, be sure to use 12-2 cable.
Disisme likes this.

Last edited by RAL238; 05-06-2020 at 09:10 PM.
RAL238 is online now   Reply With Quote
Old 05-06-2020, 09:13 PM   #6
A "Handy Husband"
 
rjniles's Avatar
 
Join Date: Feb 2007
Location: South Carolina Low Country
Posts: 11,211
Rewards Points: 900
Default

Re: Double throw switch hookup


The switch you have is a double pole, single throw (DPST). What you need is a double pole double throw (DPDT). Does not necessarily have to be center off. A DPST will have 6 terminals. Connect the line to the common terminals, connect one of the vats to one of the load terminals, connect the other vat to the second load terminals.
Disisme likes this.
__________________
My electrical answers are based on 2017 NEC, you may have local amendments.

Location: Coastal South Carolina
rjniles is online now   Reply With Quote
Old 05-06-2020, 09:34 PM   #7
Member
 
Join Date: Mar 2020
Posts: 820
Rewards Points: 1,642
Default

Re: Double throw switch hookup


Is there some code requirement that you hardwire these things???

Because from here it seems like you're *waaaay* overthinking this.




1. Rewire the vats to be cord-and-plug connected. Use reasonably common NEMA 6-20P plugs.

2. 20A circuits can have as many receptacles as you please, although some jurisdictions limit them to 12 yokes. Fortunately, NEMA 6-20R is made in duplex receptacles just like any ordinary recep.

3. Plug in both vats into the same circuit or even receptacle. Leave them plugged in.

4. Don't use both at once.

Really, this is no different than a kitchen circuit with a coffeemaker, toaster, Foreman grill, waffler and blender all plugged into the same circuit. You don't use 2 at once!

Seriously. The rules for multiple appliances in receps don't change for 240V vs 120V.

Disisme likes this.
seharper is offline   Reply With Quote
Old 05-06-2020, 11:38 PM   #8
Member
 
Join Date: Nov 2017
Location: Houston
Posts: 129
Rewards Points: 10
Default

Re: Double throw switch hookup


Line volt thermostats for 240v heaters work on a single pole type set up.
Send 120v to one side of element and switch the other side of the element through thermostat.
If I were doing this from scratch, I would use RAL238 and rjniles solution... I think breaking both poles is the cleaner and more elegant way to do it, but your existing switch will work.


Sent from my SM-G965U using Tapatalk
Disisme likes this.

Last edited by Shaneyj; 05-06-2020 at 11:41 PM.
Shaneyj is online now   Reply With Quote
Old 05-06-2020, 11:43 PM   #9
Member
 
Join Date: May 2018
Location: New York State
Posts: 1,063
Rewards Points: 2,120
Default

Re: Double throw switch hookup


Quote:
Originally Posted by Shaneyj View Post
Line volt thermostats for 240v heaters work on a single pole type set up.
Send 120v to one side of element and switch the other side of the element through thermostat.
If I were doing this from scratch, I would use RAL238 and rjniles solution... I think breaking both poles is the cleaner and more elegant way to do it, but your existing switch will work.

While I agree that it is only necessary to switch one side of the line, my preference is to switch both side on 240V circuits. So when the switch is in the Off position, everything is really off and not half powered.

The existing switch won't work because it is not double throw. It's a double pole, single throw switch.
Disisme likes this.
RAL238 is online now   Reply With Quote
Old 05-06-2020, 11:45 PM   #10
Member
 
Join Date: Nov 2017
Location: Houston
Posts: 129
Rewards Points: 10
Default

Re: Double throw switch hookup


Quote:
Originally Posted by RAL238 View Post
While I agree that it is only necessary to switch one side of the line, my preference is to switch both side on 240V circuits.



The existing switch won't work because it is not double throw. It's a double pole, single throw switch.
It doesnt need to be double throw. Vat a in up position and vat b in down position...

But as I type this I guess I realize there is no off position.

Good call RAL.

Existing switch won't work.

Sent from my SM-G965U using Tapatalk
Disisme likes this.
Shaneyj is online now   Reply With Quote
Old 05-07-2020, 01:16 AM   #11
Member
 
Join Date: Mar 2020
Posts: 820
Rewards Points: 1,642
Default

Re: Double throw switch hookup


Another option is a subpanel. Square D makes "QO" 8-space subpanels that are quite small for about $40. (mind you QO is expensive).

Replace one of your vat breakers with a 40A breaker that feeds the subpanel. Then, place three 20A vat breakers in the subpanel.

That will free up 2 spaces in your panel, since you are -2 vats and +1 subpanel with 2-space breakers.

Run any two at once. Or bump the subpanel to 60A and run all three.

If you really feel you need a nanny device to keep you from running 3 at once, fit a QO2DTI interlock on two of the breakers.
Disisme likes this.
seharper is offline   Reply With Quote
Old 05-07-2020, 07:51 AM   #12
Newbie
 
Join Date: Apr 2013
Posts: 20
Rewards Points: 26
Default

Re: Double throw switch hookup


Lots of great suggestions on how to do this. I had another look at the panel and noticed I have 3 breakers that take up double slots each and I know they're not 20 amp breakers and before I start clicking breakers off to trace what they power, I was thinking because I still have an open slot up top left why not pull one of those doubles and replace with a single 15 amp. This house 28 years ago when we bought it was electric heat so lots of 20 amp breakers were in the panel and then I changed to gas furnace, saying that, is it possible those 3 double breakers are 20 amp breakers left over? There are no markings on the exterior to say what they are.
Also something else I need to check is last year my son ( professional Hvac) changed out my electric hot water tank and replaced with a gas hot water tank, I would imagine the old electric was on a 20 amp, need to find out if he did anything with that.
Attached Thumbnails
Double throw switch hookup-breaker-3.jpg   Double throw switch hookup-breaker-2.jpg   Double throw switch hookup-breaker-1.jpg  
Disisme is offline   Reply With Quote
Old 05-07-2020, 10:25 AM   #13
Newbie
 
Join Date: Apr 2013
Posts: 20
Rewards Points: 26
Default

Re: Double throw switch hookup


Ok apparently my son switched out a gas hotwater for the new gas hot water , but he also said when he installed the new gas range the old electric was on a 40. Time to open the panel and see whats going on.
Disisme is offline   Reply With Quote
Old 05-07-2020, 11:17 AM   #14
Newbie
 
Join Date: Apr 2013
Posts: 20
Rewards Points: 26
Default

Re: Double throw switch hookup


I opened up the panel , the 3 doubles I mentioned on the left all appear to have smaller guage wire. I checked the first one down and it appears to be for the fridge or recepticles on that side of kitched , turned breaker off and fridge was off. The kitchen was remodelled 20 some years ago and perhaps new recepticles installed. What would be the reasoning for two wires going into what I'm assuming is a double 20 amp breaker such as the fridge breaker?
Near as I can tell I should only have 4 doubles , 1 for garage , 2 for vats, and 1 for electric dryer. The 4 on the Left side are a mystery.
Attached Thumbnails
Double throw switch hookup-panel-1.jpg   Double throw switch hookup-panel-2.jpg  

Last edited by Disisme; 05-07-2020 at 11:20 AM.
Disisme is offline   Reply With Quote
Old 05-07-2020, 11:22 AM   #15
Member
 
Join Date: Dec 2019
Location: Florida
Posts: 97
Default

Re: Double throw switch hookup


Those breakers with no markings on the handle look more like a disconnect breaker (not rated for amperage interruption). Those have no overcurrent protection. They need to be replaced with actual breakers.
Disisme likes this.
ServiceCall is offline   Reply With Quote
Sponsored Links
Advertisement
 
Reply


Thread Tools Search this Thread
Search this Thread:

Advanced Search
Display Modes

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





Top of Page | View New Posts