@Moortown, I have 3 sparks and 3 expansion boards setup similar to the way you want to.
answers to your questions.
1: No you only need one to control 2 SSR’s, they have an A and B channel. SO only one wire from Spark.
2: The grey connectors are on the expansion board. See picture below, you can connect one SSR to Channel A, using either the tabs on the end or the grey ‘A’ channel connector ( Both Circled Blue ), and then connect the second SSR to channel ‘B’ using grey connector for channel ‘B’ ( Circled Red).
I think any RJ12 should work but they’re generally lower quality cables so can only do short runs. The ones on the store are actually CAT5e cable with RJ12 connectors. You can make your own cables up pretty easy if you buy an RJ12 terminating tool. They’re pretty cheep on ebay.
@Moortown & @rbpalmer - I wanted to clarify the SSR boards. Based on what I have read it sounds like the boards support two relays ea. or max. and in order for the Brewpi to talk to the expansion boards there has to be a 1 wire cable (phone cable with pin out as seen below). Can you daisy chain the expansion boards like you can the control boards for the ball valves + 2 temperature sensors? Or like I have seen in the pictures you can have 1-wire cable with 2x SSRs and daisy chain using the grey connector (red). So in my case I have 4x boards, I would need 2x 1 wire cables and have the SSRs connected using the grey connector,
Input, thoughts etc. greatly appreciated. See my comments below if you need further reference.
Yes, you can daisy chain the rj12 ports.
As @rbpalmer showed, one of the grey outputs is also connected to the slots to mount to an SSR, so the easiest setup is to screw to one ssr and connect the second one to the grey B terminal.
I just wanted to add that I finally figured out (lots of life events, since time has passed) that the Pos + on the expansion boards go to the IN-x on my SSR 8x & 4x boards. And the Negative - goes to the 2nd Ground GND on my type of SSR Board. Finally got this figured out and beginning testing all my connections again.