DPDT timer?

[trivetman]

Does anyone know of a DPDT timer?

Ideally, I’d like something like this:
Intermatic FD430MW.

But with DPDT instead of DPST

Intermatic FD430MW 30-Minute Spring-Loaded Wall Timer for Lights and Fans, White - - Amazon.com

Intermatic FD430MW 30-Minute Spring-Loaded Wall Timer for Lights and Fans, White - - Amazon.com

www.amazon.com

 

[crusemm]

Why do you need the DPDT? what will it be used for ?

 

[Bama Rambler]

What you're looking for is a time delay timer. That's going to be hard to find, especially with the hand switch.

You're best bet is probably to use an interposing relay and let the wall timer control it.

 

[trivetman]

Ive got a 240V Stenner for LC now and am thinking about putting another on for MA. With a DPDT I could wire it so turning on the MA cuts power to the LC, avoiding those concentrations being put into the pipes at the same time.


Bama - it doesn’t have to be a hand switch. Any countdown timer with DPDT will do.

I am hoping to keep the relay and timer in the same device if possible.

My understanding is that its unwise to switch a 240 device by only one pole. I don’t understand the ‘why’ behind that rule. If I could do that, I could use a SPDT which I think I’ve seen.

 

[crusemm]

I currently have my pool pump and booster pump wired up to only switch one leg of the 220V supply, and that has been working fine. I will see if I can fid and link that discussion. My understanding is that only switching one leg leaves power in the motor, even if it's "off". My solution was to put warning labels on the pump motors so t6hat anyone that works on them in the future will know to turn off the breakers.

PE153 Timer

Label

 

[trivetman]

only switching one leg leaves power in the motor, even if it's "off"

That makes sense from a electrical code standpoint that switching one leg isn’t allowed. Labeling is a good precaution.

 

[crusemm]

My understanding is that is allowed per electrical code. NEC 430.84,

 

[ajw22]

My understanding is that its unwise to switch a 240 device by only one pole. I don’t understand the ‘why’ behind that rule. If I could do that, I could use a SPDT which I think I’ve seen.

Both wires on a 240V circuit are hot. Only one wire on a 120V circuit is hot. You can disconnect one wire on a 120V circuit and all power is removed. For a 240V circuit both wires need to be disconnected for all power to be removed.

Switching both wires on a 240V circuit is required by code for the safety of those who may inherit your work or work on your equipment. Warning labels are not sufficient as they often get weathered or lost in time.

Experienced electricians don't assume wiring is to code and use a non-contact voltage tester to confirm wires are not hot before working on equipment.

 

[crusemm]

I agree it's not ideal, but for some circumstances it's the only solution that works. Any work done to the pool pump motors would require opening the breaker anyway.

 

[Bama Rambler]

It is very common practice to switch one leg of a split phase circuit, and it is allowed by code. What is not allowed by code is to break one leg through a disconnect device. A timer isn't a disconnect device, it's a control device.

Having said that, I much prefer to 'switch' both legs if practical.

As for a DPDT timer there are a few out there, such as the Intermatic T7801B.

 

[frazld]

Yes please don't just switch 1 leg of a 240v circiut someone could died.
My experience 50 hp 460 volt blower motor, motor connections where corroded.
Turned off disconnect. went to re wire the split lug connectors got 1st connector undone it hit the junction box and BOOM like fire works going up in my face.
Some one had wired part of the control circuit to the terminal side of the motor disconnect and it was back feeding to the motor. Scared the heck out of me. From then on I always check the disconnect for improper wiring and the connection I am working is not hot. Also fyi some circuits that have 240v one line L1 or L2 will read zero to ground (Azusa Calif.). Always 1st read L1 to L2 then L1 to ground then L2 ground.