eBIAB control panel question

[RickyBobby380]

Hey Guys,

Forgive me if this topic has been covered before.

I am working on putting together a BOM to build my first eBIAB panel.
I've looked at a couple different builds as reference.
For the 240v power to the element receptacle, it looks like everyone is running one leg through a contactor, and then the other leg through an SSR and then the contactor.
Using the contactor to switch power on and off to the element.

My question is, why couldn't you eliminate the contactor and just interrupt the signal from the PID to the SSR to have a hard on/off switch for the element.

Thanks for the help,

 

[MarkyMarc]

The contactor is there as a fail safe. Since the SSR is solid state there is a possibility that if it fails it will fail closed. In that situation interrupting the signal from the PID would not turn it off and you would have 240v where you don't expect it. You could also use a high current 240v dpdt switch in place of the contactor if you wanted. I think most people use contactors so that they can use low current switches.

 

[doug293cz]

What @MarkyMarc said. Also, I prefer to design with the contactor/switch upstream of the SSR, vs. downstream as you describe. I believe it is good design practice to have any switch remove voltage from as much of the switched circuit as possible.

Brew on

 

[Bobby_M]

Just a reiteration post mostly. More commonly you would run BOTH the L1 and L2 hots into a double pole contactor to ensure no voltage at all at the element when the element enable/disable switch is in the disable position. If you don't use this method, you'd at least want to unplug the cable feeding the controller between uses. SSRs are not physical relays and will pass voltage to the element whether it's triggered by the controller or not (SSRs are more appropriately considered current switches)

 

[RickyBobby380]

Thanks for the info guys.
Should be able to order up everything for my panel now.