I pretty much understand the pic here:



What i needed to know is if the Relay being used was this:

http://cgi.ebay.com/ebaymotors/ws/eB...category=33721

I am thinking i can wire the fog lights using that, but I have no idea how that stuff works, so i needed to know if that was correct before I waste some money.

 

The one in the diagram and the one on eBay are both SPDT relays. This is exactly the type you need and it is a good price but do you need 10 relays and 10 sockets?

 

I just linked that ebay thing cause it was the first link I got when i did a search. I will try and find just 1.

here we go:

http://cgi.ebay.com/ebaymotors/ws/eB...spagename=WDVW

 

Truth be told you only need a SPST (that is single throw) relay for the diagram above. The pin 87A (unused in your diagram) is the normally closed (connected w/ pin 30 when the relay coil is not energized). 87 is normally open (connected w/ pin 30 only when the relay coil is energized) and is the only one you actually need for this circuit.

However in my experience SPDT relays are far more useful for other circuits. So if you buy a couple to have as spares or for other projects it's a great way to go.. I wasn't paying attention and ended up buying a couple SPST relays when I actually wanted SPDT for a project Bob here wrote up recently. I've since found other use for the relays, but man I wish I'd paid attention and gotten the SPDTs the first time!

Those relay sockets look nice. I've always just used crimp on quick connects on the seperate wires.

 

Those will work also. Notice that he charges the same $6.95 shipping whether you buy 1 or 100.

You can also buy SPDT Bosch-pattern relays at the Ford dealer or any auto parts store for $3~10. The relay sockets are a bit harder to find though.




I just bought a few relay sockets and what a difference. Sure, you can make individual terminals work but the retention on these is so much better - I'll never go back!

 

You can get relays and sockets reasonably here: http://www.allelectronics.com

It's a vendor I use often. Standard shipping is $6 for just about every order, no matter how much you buy, so get anything else you might need at the same time you order.

 

So like this:

Relay: http://www.allelectronics.com/cgi-bi...351&type=store

Relay Socket: http://www.allelectronics.com/cgi-bi...Y-2&type=store

$2.40/ea seems mighty reasonable for SPDT relays. $6 shipping for every order uh? Hmm...

 

You need to fuse the wire feeding your switch as well!!!! It only needs to be a 2 amp or so fuse at the most.

 

The diagram shows the switch power coming from the fuse panel.

 

Ah yes, it does. However, there is an unprotected side to every fuse :) If the person installing this puts the wire on the unprotected side, it does not good. Also, if you decide to tap it into a 30 amp fuse with 22 gauge wire going to the switch, you can overload the circuit long before blowing the fuse. Sometimes, it is better to make a blanket statement to cover all the little ways it could be done rather than hope it is done in a certain way.

When I was in high school, my friend and I were trying to put a lighted switch in his car for his CB. We got a little radio shack switch and proceeded to install it. Unknown to us, the label showing power, load, and ground was backwards. When we turned the switch on, it switched the power to ground. The cheap plastic switch melted and colllapsed closed. The small gauge wires all heated up and began melting behind the dashboard. Mind you, we were doing this in the parking lot of the radio shack. Looking back on it, it was really funny. Smoke was just billowing out of the dash and out the windows. It must have looked like the car was on fire. We both had these nice burns on our hands from grabbing at the wires and trying to yank them out of the dash before it actually caught fire. Moral of the story: fuse the $h1t out of everything :)

 

Absolutely!

 

Ya' got my vote!

 

I agree too. This weekend I rewired all of my accessory switches. Several were tapped into an accesory circuit (left hand +12VDC socket on the bezel) which is fused, but I'm sure the fuse value is not appropriate for what I was using it for. I added a 3 AMP fuse inline to the switches and sleep better at night..

Now I also upped the wire to ~14 guage.. which is definitely overkill considering the circuit is now fused to a max of 3A @ ~12VDC.

That said, anybody know a good rule of thumb for maximum power handling for a given wire gauge? Or conversely how to figure the right wire gauge for a given target power level?

 

Why of course! This is the chart we use for emergency vehicle wiring and installations.

http://www.kb1fpd.com/wire-gauge.pdf

 

For automotive applications, I go by what Ford uses and err toward the large side, especially on longer runs:

50A: 10~12 ga
30A: 14 ga
20A: 14~16 ga
15A: 18 ga
10A or lower: 20 ga

 

Neat, so in theory I could run up to 70 AMPs through my < 3' of 14 guage wiring harness! .. Yup, overkill like I figured..