Sprinkler wire question

[genius]

Hey all, I am trying to move my sprinkler controller (an Orbit digital job about 4 years old) to a more convenient spot in the garage. It has very thick, I would guess 12 gauge, wire going from the valves to the controller box. Is that the required thickness? I was thinking if I used cat5e, there's 4 twisted pair so I can get a unique colored wire to each of my 8 zones That would make reconnecting the wires after I extended in 25' or so of cat5e, to the timer quite simple since I know which wire would be which zone. I googled all over and it looks like minimum 14 gauge for underground use. Since I am above ground and in a garage, can I use the cat5e even though it's 24 gauge? TIA

[EXT]

I would say it depends on how much power in watts the valves draw and the voltage. 50 watts at 120 volts is .416 amps but at 12 volts it will draw

4.16 amps, cat5 cable is probably only 22 gauge and cannot carry many amps. Also cat5 may not last long in the ground and exposed to water and other elements.

[dpb]

As another poster says, it'll depend on what the actual current draw is and that'll depend on what the number of valves/zone is and the power to control each and the operating voltage level. My guess is that the answer is 'no'; there's not enough ampacity in signal cable or the spec's wouldn't go to anything as heavy as what you've quoted.

Cat 5 is, afaik, not specified specifically by conductor diameter but by digital transmission performance spec's but I believe it generally is in the 22-24 AWG range. From the following table for power transmission you see you're going to be very limited in how much current you can draw. 22 AWG is as little under 1 A; 24 AWG is under 0.6 A.

I _think_ I've seen typical lawn valve spec's at 24 VAC/200 mA holding current but inrush is probably 2-3X that.

If there's only a single valve of that size on each conductor pair you _might_ get away with it for such a short run, but the answer is you really probably need a minimum of 18 AWG and probably out to think more like 16 or so. Of course, if your valves are higher draw or more/zone, needs will go up, too.

Your surest bet is to match wire size to what is already there; one would assume the installer didn't waste materials for no good reason.

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[chaniarts]

also take into account voltage drop. smaller wire will have a larger voltage drop than larger wire.

[dpb]

On 5/4/2012 6:29 PM, chaniarts wrote: ..

Yes, but he's only got a 25-ft or less run so that's negligible factor in this case. For the overall installation it's significant, yes.

[Steve Barker]

it all boils down to how much current do the remote valves require or pull? You should be able to find the specs on the mfgr website. 24ga won't carry much current. But i can't imagine it needing to be 14. Most the rainbird installations i've seen have used 18ga or so. Some

18/8 thermostat cable may do the trick.

[DD_BobK]

SNIP

+1

I originally wired up my front & back yard sprinker valves using a 14 gage wire. I had a bunch of nearly used up 500' rolls and wanted to make sure there was no voltage drop.

The each run was about 35' to controller location......basement, which was a really dumb idea I had back in 1980. Some time later I moved the controller to a more sensible location (back yard patio).

In 2008 I redid some of the sprinkler system and was doing some crawlspace work as part of the job. I decided to run the properly sized wire, in the proper way and settled on 18-8 thermostat cable.

I didn't find 18-8 thermostat cable at Home Depot so I bought it online. After the fact I discovered that Home Depot sells burial-able sprinkler wire in all sorts of flavors....... but they stock it in the plumbing dept (sprinklers) not in electrical.....doh!

I installed a run of a cable to each valve manifold (35', 40' &

55'). The valve actuators are Champion CL-100-B's The solenoid current: In rush .59 amp Hold .33 amp

I think I calc'd voltage drop at in-rush for the 55' run at about .5 volt (2%)

Everything has been working fine since 2008.

cheers Bob

[DD_BobK]

I had a feeling someone would misunderstand my post. The thermostat wire & direct burial sprinkler wire are by no means interchangeable in all situations.

I did not bury the thermostat wire..... I don't do direct burial of any wire (even the stuff rated for direct burial), I use conduit.

I was talking merely discussing wire size.....

cheers Bob

[genius]

Hey Everyone, thanks for the all the ideas. The main reason I wanted cat 5 was that when I ran it around the garage I would have a single wire with 8 cores vs 8 exposed wires that I woul have to tie together or run through PVC. If I can find some of that 18-8 wire, I will use that since I am all indoors and not going to bury anything.

As for the this system and it's nuances, I believe it's about 40 years old and I've been in the house 6 years. There's no exposed manifolds. I had to rent a line locator and dug a ton of holes to try to find the scattered valves in the yard. 2 of the valves were covered with 1/2 a beer can, 3 valves were covered with some pajama bottoms or sweat pants. The main turn on/off for the system is 6' down in the front yard and I just had that bypassed since the valve was getting extremely difficult to open/close . They used 1" line for the sprinklers and valves but used 3/4" line to the backflow preventer. So whoever installed this system seems incompetent to me and their use of the thick 12g wire I have no explanation for but it's there, it works and I don't see a reason to not use it.

Thanks again!