What Gauge Wire For PID?

Hi all,

I've bought all the parts to build myself a single element, 120v PID controller for my ekeggle. I'm following the excellent tutorial provided here:

https://www.homebrewtalk.com/f170/step-step-build-110v-portable-pid-controller-379938/

My only question is what gauge wire is acceptable to use to wire this up? I tried using 12 gauge as suggested above and it was an absolute pain in the butt. Sorry for the simple question, as I'm new to electric brewing. As always, any help is greatly appreciated!

I've not built one of these, but I can tell you the wire size is based on the amp draw. Figure out how many amps the controller will draw and go from there. I'm guessing if it's just a controller it won't be drawing much. I can tell you as far as wiring in a house, 14 ga wire is for 15 amp circuits, and 12 ga is for 20 amp circuits. Also you will probably find stranded wire much easier to work with than solid core wire. This advice is not UL approved

I would go get yourself Spade Terminals - Should make life just a little easier...or PM me and I'll send you a couple (I bought extra for my build)

So I found this in the PID manual:

Power supply
voltage rating

85~260VAC/50~60Hz or 85-360 VDC

Power consumption

<2 Watt

What does that mean in terms of wire gauge?

use significantly smaller gauge wire for the PID itself (16 or so), use the 12 gauge for the element wiring

TMannion87 said:

So I found this in the PID manual:

Power supply
voltage rating

85~260VAC/50~60Hz or 85-360 VDC

Power consumption

<2 Watt

What does that mean in terms of wire gauge?

Click to expand...

I used (IIRC) 18ga wire behind a 6a breaker on my PID power circuits.

Thanks for your reply BigFloppy. I already have my element installed in my kettle and wired to a power supply. Will I be able to use 16 gauge wire for everything except the "incoming" power cord supply then?

In my mind, you should be able to use 16 gauge wiring for the pid, yes..

tooldudetool said:

This advice is not UL approved

Click to expand...

Even 24awg wire is OK for PID wiring.

Thanks for the info everyone. I'm gonna re wire it tomorrow and report back.

TMannion87 said:

Thanks for your reply BigFloppy. I already have my element installed in my kettle and wired to a power supply. Will I be able to use 16 gauge wire for everything except the "incoming" power cord supply then?

Click to expand...

Any of the current carrying wire should be 12ga. (or whatever is appropriate for the current/run)

so the main power cord and then the wire going out to the elements/load need to be the large gauge. power for the PID itself is in the miliamps. 16-24 ga will be fine.

So another newbie question related to the OP's. I understand that the wire bringing power in and the wire directly powering the elements needs to be 12 AWG, but what is the appropriate way to downsize to a higher gauge wire? For example, if using a terminal block is it okay to have 12 AWG on the input of a terminal and 16 or 18 AWG on the output of the same terminal (provided it's headed to a device that requires less amperage, i.e. PID)?

Thanks in advance. Cheers.

Terminal blocks work just fine. Just make sure it is rated for the total current you are gonna pull through it

Thanks Minbari. So no worries with connecting two different gauges of wire via the same terminal/terminal block?

Appreciate it. Cheers.

No worries at all, with one caveat, your main feeder needs to be the biggest wire. (Obviously)

If using lower gauge wire than total possible amperage, it's smart to protect wiring with fuses. In case of failure, 24 gauge wire will burn out quite quickly if exposed to any real current. A simple .5A fast blow inline fuse will protect the wiring (and possibly the PID) in case of a short.

Bartp said:

If using lower gauge wire than total possible amperage, it's smart to protect wiring with fuses. In case of failure, 24 gauge wire will burn out quite quickly if exposed to any real current. A simple .5A fast blow inline fuse will protect the wiring (and possibly the PID) in case of a short.

Click to expand...

I agree. You should fuse the power to everything. It doesn't matter that the PID draws 40 milliamps or less, you need to protect against the unexpected.

tooldudetool said:

Also you will probably find stranded wire much easier to work with than solid core wire.

Click to expand...

Since you're attaching directly to screw terminals, solid core is far easier to work with. If you decide to use spade terminals, then go for stranded wire.

Use 12 gauge for incoming hot and neutral, 22 gauge for DC/signaling. If you further distribute the AC then you can even use 14 guage for that. Forget about the heat-shrink spade terminals, they are crazy expensive and not needed for this application. You can get a box of 50 normal spade terminals for about 3-4 bucks.

Bartp said:

If using lower gauge wire than total possible amperage, it's smart to protect wiring with fuses. In case of failure, 24 gauge wire will burn out quite quickly if exposed to any real current. A simple .5A fast blow inline fuse will protect the wiring (and possibly the PID) in case of a short.

Click to expand...

Subdivisions said:

I agree. You should fuse the power to everything. It doesn't matter that the PID draws 40 milliamps or less, you need to protect against the unexpected.

Click to expand...

Thanks guys. I was planning a .5A fast blow for the PID wiring. I may also add one to the pump outlet. What are people generally using on pump circuits? 5A? Plan is to use 12AWG for the element/pump circuits, and then 18AWG for the PID since I can get my hands on some easily.

NathPowe said:

Thanks guys. I was planning a .5A fast blow for the PID wiring. I may also add one to the pump outlet. What are people generally using on pump circuits? 5A? Plan is to use 12AWG for the element/pump circuits, and then 18AWG for the PID since I can get my hands on some easily.

Click to expand...

March pump draws 1.4A at 120V.
Theoretically you can use wire as small as 18 AWG which maxes out at 5A.

podz said:

Since you're attaching directly to screw terminals, solid core is far easier to work with. If you decide to use spade terminals, then go for stranded wire.

Use 12 gauge for incoming hot and neutral, 22 gauge for DC/signaling. If you further distribute the AC then you can even use 14 guage for that. Forget about the heat-shrink spade terminals, they are crazy expensive and not needed for this application. You can get a box of 50 normal spade terminals for about 3-4 bucks.

Click to expand...

12 gauge for a 1/2 amp current?? Oh brother... :smack:

The wire does not need to support 20a loads it its being hardwired to a little .5amp controller your television doesnt even have that heavy of a power cord...... The component and traces inside of the controller are only built to handle the expected load.

I used 22 or 24 (cant remember) gauge myself and I do have it all protected with a 1 amp fuse... If something did go horribly wrong with a pid I would rather have a wire burn and short than a pid melt although neither are realistic. especially with the other protections like GFCI and the emergency kill switch.
Keep the 12/10 gauge for the stuff that needs it like the actual load carrying wires for the elements to the relays and ssrs....