# Correct wire gauge for control panel

### Help Support Homebrew Talk:

#### wizardofza

##### Well-Known Member
I'm currently building a Brutus-clone and I'm wondering what gauge wire I should be using for inside the control panel?

This will be 100v and on it there will be two TS-Love controllers, two March pumps model 809-HS-PL and two STC normally closed gas valves connected to the power.

I know calculating the correct gauge is based on a few things, namely resistance, length of wire run, and amperage.

The resistance I'm not too sure on how to calculate. The length of wire inside the control panel is trivial, so I'm thinking that doesn't need to be taken into consideration.

As for amperage, according to the March Pump docs, at 115v they draw about .18 amps each (man, that seems low). The STC valves will draw about 1.4 amps each and I can't seem to find the amps the Love controllers will draw (because they're switches, do they technically draw any amps?).

Does anyone have any recommendations on the correct wire gauge size I should be using inside the panel?

#### Ewalk02

##### Well-Known Member
What are the Love Controllers actually controlling??

Here are some guidelines for wire guage and max amperage (@ 0-2000 volts 3 wires in a cable)

14 awg - 20
12 awg - 25
10 awg - 30
8 awg - 40
6 awg - 55
4 awg - 70

These amperage ratings are all based on TW/UF wire which will be the most conservative approach.

OP

#### wizardofza

##### Well-Known Member
The Love controllers will be controlling the two STC gas valves @ .18 amps each. Does this determine the amount of amps the controllers draw?

So, I should go with MTW wire, right?

Man, I wish I took electrical engineering in school

#### tipicreeper

##### Well-Known Member
Two 809-HS-PL @ 1.4A (Manufacturers Website)= 2.8A
Two STC Valves (40w @ 115VAC) @ .35A = .7A (this I just picked as a common from STC's website)
Two Love Controllers draw is mV.
I'm getting 4A tops. So, add a little more for pilot lights & bling.
I'd got to your hardware store and pick up some 16 awg wire. They typically sell THHN with has a stiffer jacket then MTW and can handle a little more amperage.
You really have a low draw, just oversize the wire & you'll be fine.

OP

#### wizardofza

##### Well-Known Member
Two 809-HS-PL @ 1.4A (Manufacturers Website)= 2.8A
Two STC Valves (40w @ 115VAC) @ .35A = .7A (this I just picked as a common from STC's website)
Two Love Controllers draw is mV.
I'm getting 4A tops. So, add a little more for pilot lights & bling.
I'd got to your hardware store and pick up some 16 awg wire. They typically sell THHN with has a stiffer jacket then MTW and can handle a little more amperage.
You really have a low draw, just oversize the wire & you'll be fine.
Right on! :rockin:

I had some numbers screwed up in my OP, thanks for double checking. And thanks alot for the help! I can't wait to go home and get this thing wired.

I'll post some pics once I get this freakin' thing finished!

#### tipicreeper

##### Well-Known Member
Sorry Wiz,
Don't forget internal fusing.
Fusing is made to protect the wire. So, if you intend on just pluging this thing into a wall outlet then the wire needs to be sized to the circuit breaker. (14awg for a 15 amp & 12 awg for a 20 amp) If you put a 10A internal fuse then you can drop to 16 AWG.
This is just incase you get a direct short somewhere. Then the appropiate fuse/breaker will pop before the wire smokes.

#### tipicreeper

##### Well-Known Member
Do you have a wiring diagram?
Do you need one?

OP

#### wizardofza

##### Well-Known Member
I was planning on using a standard 14awg extension cord from the wall to the control panel that would be connected to three terminal blocks (ground, hot and neutral) that I will then run my components off that.

So, instead of fusing anything, would using the same gauge as the extension cord within the control panel be appropriate?

I do have a wiring diagram, it's the one from the Brutus 10 plans found in the BYO issue a few months back.

#### tipicreeper

##### Well-Known Member
I'm sorry, I do not have that issue. I'm just coming at this from an industrial control wiring aspect.
Yes, that would be appropiate for a 15A Circuit breaker.
My opinion you may still want some smaller branch fuses to protect some of the smaller electrical componants. For example a 1A for the 2 valves and a 1A for the Love's maybe even two 1.75A slowblow fuses for motors.
Just my opinion.

OP

#### wizardofza

##### Well-Known Member
Yeah, if you think it would be better using fuses, I'm all for it.

I'm assuming that the fuses would be the glass-tube type and I would just use the appropriate fuse blocks/holders for the fuses? Do I just use the time-delay fuses for the motors or for all components?

Thanks again for the help creeper. I truly appreciate it.

I don't have the wiring diagram here with me at work, but I'll post it when I get home (of course, not an exact copy) so you get the full picture of what it is I'm actually doing.