If I run a wire from a light to trigger a relay, does that wire need to be fused?

I've done this several times on my truck (fog light mods, aux reverse lights), w/o fuses and I got to wondering if I need to go back and add them.

 

Under all cases in general, you should have an inline fuse from the factory harness to the relay.

This is just in case you have an issue with the relay you added, that it blows the line fuse ( usually you would have a 1A fuse in between them ) that the factory lighting is not lost.
The issue would be a short to ground, not an overload type condition.

Sure there are several many installs that are out in the world that are just like you have, and work fine for decades.

 

Thanks, I think I'll add some fuses. Does it matter where on the wire the fuse is (closer to the relay or closer to the tap)?

 

Fuse always goes closest to the power source, should be no exceptions to that if you want to protect the whole line.

Edit: I don't necessarily recommend this (only because I'm a neatness freak!) but it's easy to put a fuse inline by cutting your wire just after you've tapped from whatever power source you use, putting a female insulated blade connector on each end of the cut wire and plug them directly onto each leg of standard size blade fuse. If you're concerned about the top test contacts touching something, wrap a piece of electrical tape around the fuse so that it overlaps the end and hides those contacts. Much easier than getting fuse holders, and a whole lot cheaper.

 

I'm with code58 on this, always as close to the power source as you can get.

For the case of chaffing of the insulation, and getting a short to ground, you do not want wire between the fuse and the source that this can happen to.

I have used the pre-made fuse holders where you get pigtails, these work well, one leg of the fuse holder to the circuit you are adding onto, and then so an inline solder splice with heat shrink to the circuit to the device.

past few years I changed to the roll your own fuse holders that use a weather pac type connector on the input, so I can use my own wire and not have the additional splice ( neatness thing ). This cost a bit more than the pigtail type, but I like the look better.

 

I also have, in the outfitting I did, use the 3M inline blade type snap-lock fuse holder. I'm a firm believer in replacing fuses rather than wiring, or worse, a vehicle, so I tend to fuse MOST everything (there ARE exceptions, but not many), but sometimes we had so much equipment in a vehicle that you were literally running out of room, so up under the dash where it was easily accessible I would use one of those occasionally. You cut the wire, slip one end in each side and snap lock it shut and insert the fuse.
Didn't use 'em very often, but sometimes came in handy.

 

That is handy for an install or to correct another installer's goof.

I am to the point that the soldering iron is the 2nd thing I get after wire cutters when doing an install. Then again more than once I have had solder drip on my cheek

 

Ive heard of guys getting it on their nose during a RS install.

We always used female insulated spades to make our fuse holders. Never had an issue with one in the 2 years i was in the bay.

 

Thanks for the advice/tips ...

 

Steve, THAT'S not cool! I did solder on occasion, but not very often. I was VERY careful about the crimped connections though. And only EVER used the long handle top quality crimpers. I tested the crimps several times (not in the car, in the vise) and the wire would break before the crimp ever let go. I only ever used the UNINSULATED crimp on insulated wire. I have seen the () insulated crimps pull apart when pulling a M/F blade connector apart so refused to ever use that type of crimp. Ca. is so dry (here anyway) that corrosion is not a problem for us. I figured that virtually every car manufacturer uses crimps throughout the car, except for the boards, good enough for them, good enough for me. We NEVER had problems with them. I also prefer top quality fine strand wire to eliminate "air gap". The work we did, dare not fail, and it didn't. Believe it or not Steve, the rare time I ever had problems with a connection was when a wire would break from age and rough use (as in Expedition used in rough canyon service) at the edge of the solder which was the vulnerable point because of inflexability and embrittlement from soldering heat. Didn't happen often, but I did see it 3 or 4 times.

 

What you are calling the uninsulated crimp is for both in AC electrical.
The half moon crimp () I have seen called an automotive crimp.

The best thing about dad being an electrician, right from single digit age, he told me the automotive crimps are useless, don't ever both using them.
That and how to line up the terminal so it does not push apart in the crimp. The 'fold' in the round ( where the metal over laps to make the tunnel for the wire ) always goes in the arc, and the solid side is always in the point.

I had some pictures of this in the old gallery, not sure where what happened to them, for members to see which way to position the crimp. Not everyone knows this.

Crimps are at least 40% of motor control boards, I have made a lot of crimps over the years in these, to the point where work on trucks is a rounding error for crimps.

The wire breaking at the edge of the solder, I have seen that one myself. You would think stranded wire would not do this, but it did.

 

Steve- Your dad taught you well! Spot on. I personally don't know why they even make the (automotive, () ), to me they are worthless, I actually learned way to long ago to admit, that the "spiker" was the only way to go. I have seen guys use the (), and tried to tell them to throw 'em away. Some of the guys use the standard crimpers (spikers) to crimp the large (yellow) butt's and I hated what it looked like, but wasn't able to find any that fit the large, only the small red and medium blue. I tried all the professional tool trucks and even professional electrical supply, no luck. Being picky about my work, I bought a pair of Channel Lock electrical crimpers (long handle), used a die grinder with appropriate size bit and "made" my own. They look just like factory, like what they all should have been offering, but weren't.
Steve, I know soldering is supposed to be the Gold Standard, but the embrittlement of the wire is the reason I didn't do it real often. We used 50-50 solder and I used a paste that was terrific for instant purging. I put a small dab on the joint and (240 gun) let it get good and hot and hit the solder to transfer and then hit the trigger and INSTANT flow. I NEVER held the gun on the joint till it heated, purged and flowed. Most of the guys did, and you have the burning, melting of the end of the insulation that way, which I didn't like. Though I used the same flux cored solder they did, the paste I used was the trick.
I think the small gauge wire is even worse for embrittlement than the larger gauge, greater chance of breaking after a little while. Just one of the reasons I didn't do much soldering.

 

The 10-12 AWG yellow insulated crimps do not have a sense of humor with the spike type crimp.

The Stakon terminals seem to have a different insulation material, that they do not turn into a nasty knot on the end of the terminal ( brand x seems to a harder plastic the T&B seems to be a nylon composite )

I use the crimps I got from dad, a pair of T&B Stakon crimps, the 10-12 is a rounded spike, vs the blue / pink which is a proper point.



The past 10 + yrs I have gotten into the habit of cutting the plastic insulation off the terminal, and using marine heat shrink on all terminals ( unless it is the insulated hood type female or the male type for the 3M t-taps ).

This lets me get a good double crimp on the terminal ( so the wire tube is crimped the entire length ), and push the heat shrink up to the spade part ( or ring if that type ) having the goo melt around the terminal where it is crimped at, so the only thing that is open is the flat part of the metal ( push far enough, and the wire tube is completely covered ).

Don't know where I got this from ( if it was you, thanks ) but I find these to be great for attaching wire harnesses to frames.

http://www.peel-n-stick.com/t-wirestrap.aspx

I use a layer of splice pad ( that is the generic name I got from dad, 2x2 rubber pads for split bolts for overhead services ) and then liner tape over that on the harness to make the mount point for the wire strap. This works just as nice as the rubber lined 1 hole straps and no worry about them rusting and don't have to drill the frame or what ever I am mounting to.

 

As stated Steve, when I got a pair of CL crimpers and modified to the right size for the yellow connectors, all was well with the world. I even rounded the sides of the 'passageway" just a little so there wasn't any "cutting" of the insulation from a sharp edge. Why don't tool manufacturers make the "stake" crimpers for the yellow? What do they use on 'em? I tried every source I could think of (all professional tool dealers), and even researched it online and never was able to find any trace of them. I couldn't stand what the regular crimpers did to the yellow, ugly!
I don't know what brand they were but we used the best connectors you could buy. They were really nice. Nothing like the standard connectors you buy at parts stores. We bought a thousand to a bag, so I'm sure they didn't cost what they would in small quantity. I'm sure they were nylon, as you said. They also had the secondary "funnel" to keep the wire from snagging when inserted.
Yeh, the regular pliers I had were the same as your picture, T&B. The modified, as stated, were Channel Lock.
You mentioned the double crimp. I have a nice set of GB (I think that's what they are) from Lowe's that have the wide jaw that will crimp that width in one crimp, but I rarely ever use 'em, because the are standard length handles and it takes too much effort to do the double width crimp without the leverage of the long handles. When I crimp, that thing isn't ever coming loose! As I stated, I have tested the strength of the crimp by clamping the fitting in a vice and clamping a vice grip on the wire, and I have NEVER had a wire pull out, the wire always breaks rather than pulling out.
Sorry, Steve, the Peel-N-Stick didn't come from me. Nice looking stuff though. I've never seen it before. My work was pretty much ALL custom stuff and when I did a truck (box) or tractor, I always had an existing loom to zip tie to. Pretty much EVERYTHING got split loomed. One rule of thumb, never drill a truck frame. I never had to, but would have found another way. I'll share with you later my method of attaching when there wasn't anything to attach to. (but not truck frames)

 

In dad's line of work, the insulated type is very rarely used.

Most terminals ends in the fork and ring are being terminated in an area where the insulation does not matter. ( terminal strip, the screws on an outlet in commercial, screws on the CT meters, screws on relay bases, etc ).

Most other times, the terminal strips or the equipment have the clamp type set screws with the plastic sleeve:


The outlets seem to be moving towards this, so the wire is inserted from the back and the screw tightens the clamp ( those really makes a mess out of doing wire saddles in a line of outlets ).
I can only tag a SWAG on why, as too many people were using the push in termination for line vs 1 additional device ( those push in terminals on the old outlets were just a service call waiting to happen, dad hates using them ).

The frame part, I was talking about the #6 short self tappers. I have not tried it in years, but it is a huge PITA.