Mosescase

ok for all you smart guys out there i found a wiring box diagram and some pictures take a look and tell what you think and if you see any flaws let me know.here are the diagrams for the relay box and the switch panel. also some pics of the final product. tear it apart so that i can know whats wrong i really like the set up but want to make sure that its safe.

Mosescase

no one????

bobvalli

I guess it would work. Before I put money on CAT5 to control the relays, I'd calculate current to the coil to make sure the wire can sustain the flow without overheating.

CAT5 is like 24 gauge.

You would have to take resistance readings of the relays coil, then use ohms law to calculate the current it will draw while operating.

Then dividing Voltage (12) by that resistance (??) will equal current

Then look for the ampacity of 24 gauge wire, de-rate it by 20% to compensate for the heat produced by the current flow and you'll know if CAT5 has the capacity to power the relays under constant load without burning up.

Other than that, it looks pretty straight forward.

Ender

Very nice, a lot of people wouldn't go through all that planning, hopefully it pays off and you wont have any problems.

EVcherokee

I see problems using CAT5 wire. Its too small...its a signal wire not a supply wire. First think about voltage drop, then realize the more those tiny wires heat up, the more the resistance, which makes more heat, which makes more resistance...and on and on till the wires burn up. Its called a cascade-affect. I'd use at least a 16ga., but lean more torwards 14ga. My .02

Other than the wire size, your design looks really sharp and clean!

longship

Also, the Cat5 cabling is solid cored, not designed for areas subject to vibrations.

You'd be better off using multicored cabling for trailers/caravans. You can get in 7 way lengths.

Rob

ProudXjOwner

I was going to do the same exact thing. The coil shouldnt draw that much on a relay that size so I dont see why cat 5 wouldnt work.

phsycho

I also have to say that the cat5e should not be used. Very brittle wire and as someone already said it is a 24ga wire which wil not carry the ampacity that you will need. (even at 12v)

ProudXjOwner

Cat 5 wire in 24awg will handle a maximum current per conductor of .577 amps, so you just have to figure out the draw of your relays and go from there.

ProudXjOwner

In a DC relay coil, the coil resistance determines the current flow through the coil. The current draw by the coil of a bosch(5 pin) relay is ~0.160 amps (~75 ohm coil).

mud-dog27

thats FitchVA's setup from jeepforum, not sure which model but ive seen lots of people use his setups with nothing but good things to say bout it

heres a link to the several variations of his switch/relay boxes

http://fitchva.com/jeep/?cat=4

Mosescase

fitchva.com had the best set up and the best explantion i just wish there would have been a list of what he used like what size those relays are cause i have no clue. By loking at the pictures can anyone tell what size those are????

bobvalli

Physical size, the rating of the contacts are all moot points. It's the resistance and current requirements of the internal relay coils that are the question.

That info should be available on a particular relays spec page. If you're dead set on using CAT5, look for a relay whose coil requirements are less than the capacity the wire can provide while supplying a sustained flow.

How about using SCR's (even if you use them between the switch and the relays coil)? If you're set on CAT5 as the control circuit, that setup should definitely work.

USMCJeeper

I have built this setup exactly as shown after referencing fitch.va and I must say it is amazing. No problems overheating.

mjs302

Whenever I'm building something like this, I prefer to use the switchs to control the ground side of the relay. That way I don't have to run a lot of hot (positive) wires. By switching the positive side of the circuit, you need to run power from the battery to the switches and from the switches to the relays. That creates a lot of potential for shorts in the new wiring. If you control the ground side, you just run wire from the relays to each switch and then to a nearby chassis ground. Then if one of those wires chafes and shorts to ground, the only thing that happens is that accessory comes on. No fires or melted wires.