electrical connectors

[david craft]

just wanted to share a little about electrical connectors. crimp connectors come in a range of quality as do wire nuts. they are often criticized but getting a good quality connector and proper installation goes a long way towards satisfactory performance. look for a thick wall on the crimp connector where it makes contact with the wire. that will ensure it holds a crimp well. good wire nuts are edge wound square wire inside instead of round. they will actually bite into the wires you are connecting. you should be able to twist these on tight and then test by pulling hard to ensure they are secure. i got a pic of connectors but cant figure how to post...sorry

[Rich Thomas]

I don't think David was stating he rebuilds the electrical system when he dose trailer brakes. I believe he just used the reference to assert that wire nuts are a good choice for that application. 

[Ralph Javins]

Good morning; 

Interesting. " . . .  ive used them to do electric brakes for years and never had one fail before the brakes wear out." 

I did not realize that part of a brake job is to rebuild any of the electrical wiring system associated with the brakes.  All I have done is to conduct a functional test of the system and perhaps make some voltage checks with the brakes applied to see if I might have any high resistance connections in the circuit. 

One practice I have followed when working with trailers for boats is to use the soldered crimp connectors with 3M Scotch-Kote, 3M 33+ or 88 vinyl tape, and heat shrink overall as the main physical protector for those connections that I know are going underwater, especially in salt water.  The Scotch-Kote provides the main barrier against water getting to the wiring conductors and the soldered crimps.  It is a pain to work with, and it does take a while for it to dry before you can put anything over the top of it.  

Ralph, Latté Land, Washington 

[Rich Thomas]

I thought I would jump in here. I agree with David, the best solution for joining two wires is a solder joint and shrink tubing. I usually tape over the shrink with vinyl electrical tape it will protect the shrink tubing from abrasion. and shrink tubing is pretty tight and moisture isn't an issue. Wire nuts are good in a dry environment but like all mechanical connectors repeated heating and cooling they can loosen over time. That's not saying they are bad, they just need to be looked at from time to time. Wire nuts can be sealed by placing RTV or similar material in the opening after the nut is tightened fully if need be. Crimp connectors are good as well but they have limitations too. You can over crimp them, or under crimp them. Over crimping can cut the conductor causing a reduction in the current carrying capacity of the wire at the connector; under crimping causes loose connections.Think of intermittent power problems and full on connection failure.  That's why the crimp tool has specific slots for different size conductors and why connectors are sized for different wire size and applications. They are color coded as well. The worst connector is the push pin type where you put the wire in a slot and push it in. No matter what you choose to use fallow manufacture guide lines and be safe. Also you can clean up your engine bay with split wire loom tubing and this is where a butt connector is better than a wire nut. (google split wire loom) to clean connection points such as relay connections, use an eraser on the end of a pencil. Try it on a copper penny and see how it works any ways that's my 2 cents worth have a nice day!

[david craft]

here in cali, i dont hesitate to use wire nuts in undercarriage applications. we are not salting the roads here. not sure how they hold up elsewhere. will they fail?...eventually. but ive used them to do electric brakes for years and never had one fail before the brakes wear out.

[Dawn Michelle]

Wire nuts also seem the easiest to use (especially if you have weaker hands for the crimping tool). I guess in my head thought since I always saw the butt splices being used for automotive wiring that it was the preferred method...is it just because the butt splices keep a "tab" (for lack of a better word) from hanging about and being in the way (ie neater)?  Would you not use the wire nuts if it was an undercarriage application (like say you were hooking something into the taillights - backup camera) where it might be more exposed to the elements?

[david craft]

rosin core solder and heat shrink tubing is best most likely. some heat shrink is better than others. i have seen the combined item and it looks good. i have no idea how these hold up. i would imagine quite well. they have a clear tubing that allows one to view the solder joint and it seems to have good fluxing action as the solder flows. the connection has to be accessible enough for one to apply sufficient heat. a bic lighter is enough to do it. ive seen these connectors in the "butt splice" application only though others may exist. the volume and practicality of the connectors ive needed in my work never really gave me the chance to use them. but they would be a good choice for your start relay since you could remove the connector from the relay and then solder the butt splice. other than to protect connections from chaffing, i usually dont tape up connections. i feel that once wet, taped connections retain moisture and promote corrosion. this is just my own logic here having seen many corroded taped connections over the years. as far as choice of connector, ringed crimp for screws and bolts. scotch locks and wire nuts and butt splices for unions. location may deem the best connecting connector unsuitable. I personnaly like wire nuts. they have so much surface area for connecting.

[Dawn Michelle]

David - could you offer some quick tips (or rule of thumbs) on what connectors to use in different situations?  In addition to the two you've mentioned are there times it's really better to go with soldering and heat shrink tubing?  And what do you think of some of those connectors that have solder in the heat shrink?