240v to 120v switch

[Wacki]

I have a 240v control panel currently wired, but I want to be able to run the element at 120v (1/4 power) for rims.

I'm told that a spdt switch would work, but would a 120v 30a spdt switch be what I'm looking for?? I would only be controlling one of the hots that go to the element outlet, but I'd rather someone with more knowledge or who has implemented this provide some input...

 

[ajdelange]

The problem is that you have the ends of the element connected to the two hots. With a spdt switch you can connect one end of the element to either the other hot or to the neutral if the neutral is available. If the neutral is not available (grandfathered clothes dryer circuit) you may be tempted to connect the other side to the earth (ground wire). Resist that temptation. Instead buy a 30 amp diode with suitable PIV rating, connect it in series with one of the hots and put a spst switch across the diode. When the switch is closed you have full power. When it is open you have half. Note that if switching between 220 and 110 the ratios are full and 1/4.

 

[The10mmKid]

Can we assume you have a 4-wire system?
(need a neutral)

'da Kid

 

[Wacki]

Can we assume you have a 4-wire system?

(need a neutral)



'da Kid

Yes, sorry. I have a brand new 3wire plus ground circuit. I have neutral in the box already.

 

[sumbrewindude]

I know on here Bobby had a wire diagram for his on demand sparge water system using a RIMS tube and a DPDT switch the element from 240 to 120. I have it saved somewhere, but if you do a site search for "on demand sparge" you should find it.

I can't recall who made the 240/30A DPDT switch, but it was a HVAC company. Ran around 50-60bucks if memory serves...

 

[Wacki]

I know on here Bobby had a wire diagram for his on demand sparge water system using a RIMS tube and a DPDT switch the element from 240 to 120. I have it saved somewhere, but if you do a site search for "on demand sparge" you should find it.

I can't recall who made the 240/30A DPDT switch, but it was a HVAC company. Ran around 50-60bucks if memory serves...

Thanks!! I knew bobby had a setup like that but couldn't find it in my searching...

 

[ajdelange]

Yes, sorry. I have a brand new 3wire plus ground circuit. I have neutral in the box already.

With the neutral present it's a simple matter of connecting one end of the element to the common pole of the switch and tying the other poles to respectively the neutral and the remaining hot. This selection gives you full or 1/4. By putting the diode in series with the common pole (and wiring a second SPST switch across that) you also have the choice of 1/2 or 1/8 power.

 

[Wacki]

With the neutral present it's a simple matter of connecting one end of the element to the common pole of the switch and tying the other poles to respectively the neutral and the remaining hot. This selection gives you full or 1/4. By putting the diode in series with the common pole (and wiring the switch across that) you also have the choice of 1/2 or 1/8 power.

How do I know what kind of switch I would need?? I know SPDT, but do I need one for 240v and 30a?? Or would I be ok with something else??

Thanks all for your input!!

 

[ajdelange]

It's in a 240 V circuit so obviously it needs to be insulated for well above 240V. It must also be capable of interrupting the full current load of the heater. If you have to ask these questions you should not be undertaking this kind of work. Get someone who knows what he is doing to help you.

 

[The10mmKid]

If you know how to use an OHM meter, you could try one of these:

http://www.menards.com/main/electrical/wiring-devices/switches/30a-3-way-single-pole-switch/p-1402913-c-6324.htm

You must make absolutely sure the switch 'breaks' before making.

I cannot tell you if this one does as it is not in front of me.

The common goes to the element.
One terminal to the normal Hot
The other to Neutral.

To do it properly and professionally would require a relay.

'da Kid

 

[The10mmKid]

Pass & Seymour has some info:

http://www.legrand.us/passandseymour/switches/industrial-grade/ps30ac3i.aspx

'da Kid

 

[Wacki]

Pass & Seymour has some info:



http://www.legrand.us/passandseymour/switches/industrial-grade/ps30ac3i.aspx



'da Kid

Thanks, that's the type of information I was looking for. I was also thinking a spdt contactor/relay would work, but like I said I'm not exactly sure how to look for the type I need or if there was a better solution, and some are crazy expensive.

And thanks for the links to the Menards switch and description, it looks like it does make a positive break. Also Looks like a min order qty of 6...so I may ask well just go with a relay/contactor.

In any case, my initial thoughts were to use a SPDT (or DPDT, they seem more common/cheaper) relay/contactor, which should be rated at 240v and at least 25amps. I just wanted to hear if anyone had other solutions...does anyone see a problem with this?

 

[Wacki]

Would this relay work?? (The 120v ac coil version). I don't see why it wouldn't, it's rated at 40a 250v AC...

http://m.ebay.com/itm?itemId=331055568192

 

[Wacki]

I know on here Bobby had a wire diagram for his on demand sparge water system using a RIMS tube and a DPDT switch the element from 240 to 120. I have it saved somewhere, but if you do a site search for "on demand sparge" you should find it.

I can't recall who made the 240/30A DPDT switch, but it was a HVAC company. Ran around 50-60bucks if memory serves...

Just for completeness if anyone else looks at this thread, Bobby used a Bryant 3025 dpdt switch in his setup, costs around $35-40 as I can see. I can't link but the thread is titled "On-Demand Sparge via RIMS"

 

[ajdelange]

I had the additional thought that a reversing starter (on/off/reverse) for a 3 phase motor is an excellent solution here. Connect L1, L2 and N to the three input lugs and the heater to two of the output lugs (don't use the third). Just be sure that N is not connected to the terminal that does not get reversed(two out of the 6 possible wirings of the input won't work). This arrangement lets you run at full, 1/4 or 0 power.

 

[Wacki]

I had the additional thought that a reversing starter (on/off/reverse) for a 3 phase motor is an excellent solution here. Connect L1, L2 and N to the three input lugs and the heater to two of the output lugs (don't use the third). Just be sure that N is not connected to the terminal that does not get reversed(two out of the 6 possible wirings of the input won't work). This arrangement lets you run at full, 1/4 or 0 power.

Interesting, do you have a link to this type of setup??

 

[ajdelange]

If you mean have I found a switch at Home Depot that will do this, no. In fact I've had a hell of a time trying to find any 30 amp switches. I did stumble on a starter that would do this for $20 when I wasn't looking for starters but later when I got the "hey that's a thought" flash I couldn't find it again.

 

[Wacki]

That's how it seems to go!!

Any thoughts on the SPDT relay I posted about above??

(Or here: http://m.ebay.com/itm?itemId=331055568192#)

 

[The10mmKid]

Would this relay work?? (The 120v ac coil version). I don't see why it wouldn't, it's rated at 40a 250v AC...

http://m.ebay.com/itm?itemId=331055568192

Sure.

The common again will go to the heater.

You will need to decide what is the normal 'unenergized' state state of the process going to be.

This will be the NC contact. (Normally Closed)

Apply power to the relay, the contacts change and your other process will take over.

That would be a tough call for me as I don't have any experience with the heating method you aspire. (Makes sense to me what you're doing)

My first inclination is the Hot leg feeds through the NC contact.

'da Kid

 

[ajdelange]

That's how it seems to go!!

Any thoughts on the SPDT relay I posted about above??

(Or here: http://m.ebay.com/itm?itemId=331055568192#)

Shouldn't be a problem and the price is right. One side of the heater goes to the common terminal and L and N to the NO and NC, or other way round depending on what you want to be the default (de-energized) configuration. Relays of that design are definitely break before make.

 

[Bobby_M]

The Bryant 3025 is what I chose because it gave me both a voltage switch and an "OFF" which is absolutely recommended. If you've already taken care of killing both hots in your controller, you can get away with a cheaper SPDT 30a switch where the common goes on one terminal of the element and the two switched terminals go to L2 and N assuming the L1 is going to the unswitched element terminal. In other threads, there were a lot of unexplained nay saying about using the Bryant 3025. It's rated by the manufacturer to handle 30a @240v.

 

[Wacki]

The Bryant 3025 is what I chose because it gave me both a voltage switch and an "OFF" which is absolutely recommended. If you've already taken care of killing both hots in your controller, you can get away with a cheaper SPDT 30a switch where the common goes on one terminal of the element and the two switched terminals go to L2 and N assuming the L1 is going to the unswitched element terminal. In other threads, there were a lot of unexplained nay saying about using the Bryant 3025. It's rated by the manufacturer to handle 30a @240v.

That's a great point, Bobby. I have a DPST 240v switch from lowes controlling power to the element as a "master" shut off. Otherwise I would be looking closer at this solution.

This is the switch:
http://m.homedepot.com/p/Leviton-30-Amp-Industrial-Double-Pole-Switch-White-R62-03032-2WS/100356941

I actually plan to run the relay (to select 120/240) and then a dpdt contactor after that switch above so I can select either of two element outlets and have each one capable of 120v or 240v. The idea being one element will control a rims tube with a big element run at 240 for recirculating/heating water in HLT, or 120v for recirculating during mash. Then the other outlet for the boil kettle. Not sure why I would need to run the BK at 120v honestly, but it's easy to implement and have the optionality with the configuration I poorly explained above... I'll post a diagram/pics when I have it sorted out and complete.