ECC Forum

I have been reading The Electric Brewer's guide on how to build an enclosure and I find most of it to be very helpful. However, one part of it has my head going in circles. In particular, this page:

http://www.theelectricbrewery.com/contr ... t-2?page=7

He says he is using a DPDT relay for the power on switch. Why doesn't he use a SPST relay instead? In his diagram he only shows four poles being used. I think I see in the pictures below that he has two wires coming from the power-in receptacle (which would mean five poles used, two for the coil, one coming 'out' on the top 1, and two connected at the bottom 1 and 2). Am I reading this right and the drawn image is just missing the other wire? Is this because he is running 240v? The way I understand DPDT relays is they are useful if you want to have power on one circuit when the relay is powered, and power on another circuit when the relay is off. Am I missing something else where the DPDT has some sort of duplex ability that allows you to input two 120v to get 240v?

I am running 120v (propane is my heat source, not electric), so could I use a SPST relay to effectively do the same thing with a turn key start switch, or would I even need the relay for the keyed switch (assuming I can find one that can handle ~10 amps since all my enclosure's power would be coming through the keyed switch)? The highest amp draw my system will have is 3 amps (pumps), and I have three total.

I think that diagram he has is a bit confusing. He's describing 120V circuits, but his input says 240V. If it really is only 120V, then you could use a SPST contactor. However, based on the power outlet he has there, the input power is 240V, which means two hot leads. I think where he has them labeled as #2 on the right of the contactor should have the second 120V leg going through that side. If that's the case, you could use a DPST contactor instead. He may have just used a DPDT contactor as that is what he had.

Kal is just showing the BLACK 120v side of the wiring... The #2 side 120v RED is in other diagrams ...
and is not shown here.
hope this helps.\
Skip

Having built the "Kal" panel from scratch myself, I can confirm all the schematics are flawless. As StacyR mentioned, the schematics are simplified to span multiple pages and break things into steps, whereas the photos may be looking ahead somewhat.

In this case, as JonW mentioned, a DPST contactor would also do the job (as long as it was NO), but is likely harder to find.

I agree, I also built the control panel from scratch and his documentation is perfect. and yes broken up into steps to make it easier. Those pictures are not master wiring diagrams but rather step by step implementation guides.