I want to add some lights that turn on when my dome lights turn on. I am going to use the wires in the door that light up those little lights (in the door of my 2001 Supercab) i was just wondering if they sell something that u use to splice an extra wire off it. I used to just cut the rubber off the wire i wanted to use as power, then wrap the new wire around it and then cover both in electrical tape. but im hopeing there in something that will be more professional looking and probably safer.

 

Almost any parts store, home improvement store or hardware store will have wire strippers like what is below. They automatically adjust to either spread the insulation, or strip it from the end of a wire. Spread where you want to tap the circuit, split the copper strands with a test light or awl, feed the new wire, close the gap you created around the new wire, and wrap the new wire around the source and then tape it. This is the most secure, and strongest connection you'll get without soldering, though you can add solder if you want. Do not use Scotch-Locks or that type of connector. They are bulky, often have exposed metal and can actually cut strands of the wire you need, weakening it and causing arcing and possible failure of the circuit down the road. I know millions have used them, but after 10 years servicing Ford electrical systems, I won't put on in my vehicles.



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At Napa ( maybe other auto stores also ) they make an inline tap, that you crimp onto the wire, without stripping the wire. Fully insulated, so no tap is needed.
The other part is a male spade terminal that plugs into the inline tap.
Looks like this :
http://www.partsexpress.com/images/082-140m.jpg

The same setup as what you where talking about with the wrap and solder method, but it is removalable.

If nothing else, you could go the old school method of using a Scotchlok connector, which is very similar, but the wires are crimped together at the same time, and the tap is not removable. The insulating jacket snaps around the teeth that are used to pierce the jacket, so it is fully insulated. These things have been around for years, and if you buy a good brand, they hold up as well as T tap and solder method. Cheap ones fall apart after a few weeks of being banged around on the road.
Looks like this :
http://www.partsexpress.com/images/082-100m.jpg

The color code is for the size of the wire.
Red : 22 to 18 AWG wire
Blue : 18 to 14 AWG wire
Yellow : 12 to 10 AWG wire.

Good luck

 

Scotch locks work just fine if used correctly.
The problem is most have no idea.

Did you know that there are 26 sizes of scotch locks.
They are made for stranded wire in almost every gauge as well as for solid copper wire. They should have covers that go over the metal crimp. Do not use a double open ended if you are only splicing into one wire.

It never amazes me how people will condemn something because they saw a problem with people using it incorrectly. I could make a bigger case for people stripping into their existing wiring and cutting wire accidently as well as not tying into a wire correctly and it pulls apart or put duct tape or scotch tape on a wire connection or no tape at all.

The correct way and mil-spec approved way to tap into a wire involves cutting the splice, tinning both ends to be connected, forming a hook on either tinned end. Then hooking the two hooks together, twinsting them and soldering them together. This makes a structural joint stronger than the actual wire it came from. Then to correctly cover it it should be covered in 2 layers of increasingly larger shrink tubing.

Who does this, huh?

Every connection done the way momalle1 says that comes in my shop gets re-done. Not because he does them wrong, but because most are done wrong.

 

I'll agree with C.O. in that if you use them properly, Scotch Locks are a decent way to splice into a wire, but I hate the darn things. The big qualifier I'd add is being careful where to use them. If you use them inside the cab, they generally will work OK. If you use them anywhere outside the cab - where they are exposed to weather - the problems start. I've repaired or replaced numerous wiring harnesses that some idiot at the local U-Haul tapped a trailer pigtail into with Scotch Locks and simply dissolved the copper condutor at the splice. There are ways to make them live longer - like loading them with dielectric grease, but generally speaking, they just put off the disaster.

How would I recommend getting power? Tap in properly at the fuse box. There are several products out there that make this very easy and safe. Trust me, they're worth it.

 

Actually, because so many do it improperly is primarily why I don't like it. Most parts stores will carry one or two sizes, and most people ARE inexperienced, so they do it incorrectly. Also, you are still compressing stranded wire against a metal clip. It works, but it's not exactly ideal. As far as the method I outlined, it is EXACTLY the method recommended by Ford Motor Company. Maybe it's just my experience, but I can't see how anyone could do that wrong, but I have seen Scotch-Locks that are too small installed as well as the metal tab poking through plastic hasp, when I give advice to someone inexperienced, I am afraid of them using Scotch-Locks.

As far as the "correct" mil-spec way you outlined, I agree but you are only connecting two wires, the original post wants to tap into an existing wire, why cut it, but if you did, in order to add shrink tubing (never a bad idea) you would have three wires to connect, not two.

2-Stroked is right on, if you need 12 volts, but this poster is looking for a switched 12 volts for the dome lights, this usually an 18 guage wire, another reason I can't recommend a scotch-lock here.