Electrical Wire & Connector Question

Either is OK for 18 AWG -- does that help?

18 AWG is about the smallest wire gauge used on a Ferrari (about 0.8 mm^2); whereas, 1.0 mm^2 is very commonly used (while 17 AWG would be the closest equivalent that's almost unobtanium so 16 AWG could be used for those). In the photos of the Mate-N-Lok connectors in your other thread , I'm sure there's a mix of 0.8 mm^2 and 1.0 mm^2 wires so using the terminal that can accept 15-18 AWG wire seems like the logical choice to me (especially if you order some extras, which you should do, and keep them as spares) -- JMO.

 

The amount of current a wire can safely handle is based on its cross-sectional area. Thus, an instrument light bulb can use a very small wire whereas a headlight bulb would use a much larger wire. The designers of the wiring harness know the current draw for all the electrical sinks and choose the appropriate wire sizes and fuses to prevent an electric overload which could lead to a fire.

 

As your wire size should work with either connector, go with the 18-22 gauge. I assume you talking about a crimp connector. Using the 15-18 size you run a risk that the crimp will not firmly grasp the wire. This my opinion, but if faced with choosing a crimp connector, choose a gauge such that the wire is in the middle of the spec. E.g., if you had a 16 gauge wire, choose the larger connector. If your wire gauge is on the small size of the connector spec (e.g., you had a 22 gauge wire for the 18-22 connector) you could apply a small dab of solder to ensure good grip and contact.but not too much, if you apply solder and it wicks up the wire, this will weaken the wire at the point where wicking stops and the normal stranding begins. Another technique if your connector is too large for the wire is to strip off a bit more insulation and fold the wire strands on themselves to effectively double the thickness. Some people would frown on this but it will help ensure a good grip when you crimp.

 

By the way, I forgot to mention, that if your wire size is say 20 Ga or 22 Ga (pretty small) I would avoid insulated connectors as they typically will not crimp as well as uninsulated connectors. Some people shun insulated connectors of any size. Use a bit heat shrink tubing if you need to insulate.

 

You've also got to take into account that on older cars (up until the late 80's?), the insulation of the wires was much thicker than on modern "thin wall" wires (that are even cheaper than the cheap cables we already had). If you do have thin insulation 18Gauge wire, I would go for the 18-22 connector as the bigger connector may not grasp the insulation (as mentioned by @bisel). By contrast if you've got the old-school wire with twice as much PVC insulation, you should go for the 15-18 connectors.

Connectors are cheap, so I buy various sizes just in case. Also bear in mind that connectors can be supplied with various thickness (the sheet of metal they are made of may be more or less beefy). The higher quality ones are a safer bet but much harder to crimp if you do not have a proper tool.

For the occasional odd size, I do add a bit of adhesive shrink tubing to the cable insulation. This provide additional grip for the connector.

 

This is the correct answer and explanation. And "adhesive shrink tubing" is a very important addition.

Ali

 

Just a note.....there is also considerable differences in the quality of brands of crimp connectors. Having worked in the aviation industry for 40 years we always used "Amp" brand crimp connectors and had a considerable selection including "heat shrink" incorporated connectors, removeable "knife" connectors, tabs, splice, etc etc. Also buy a quality set of crimping pliers that will provide a strong even crimp when applied. Never solder as the joint will be brittle and fail.

 

Sometimes we do have to be creative: as a last resort soldering a suborn cable, adding heat shrink tubing, or even adding a dab of MG chemical silver conductive grease can save your day!

I do appreciate to work with suppliers that do offer various quality of the same connector, at least they honestly let you know which ones not to buy...

I think AMP is now TYCO.

As far as suppliers are concerned, either you need large quantities and in this case that's Digikey (US based customers) or TME.eu (Europe), but if you are after small quantities the previously mentioned ebay seller does provide most of the connectors required for the vintage Ferraris, including the hard to find "Bosch/Junior" K-jet connectors. If it were not for the Brexit, British sellers would still be my top pick for all these hard to find bits and odds that can easily spoil a rebuild.

 

As long as you are soldering the connection and using heat shrink, it doesn't really matter much. I'd use whichever one allows you to get the best mechanical crimp on the wire prior to soldering everything.

If you have a situation where the smaller spade is tight, you can open it up prior to crimping using an awl typically. If the other size is loose, then you can double back the wire and crimp it or tin the wire first, then crimp down on that and solder again.

Ray

 

Awg22 is a nice compromise between high current and ease of use. For 3A or less even smaller is ok. For absolute max you need whatever you can fit since at that point motor trader mOhms matter. Spring bypasses make more difference than a small change in wire guage. In some instances you can simply double up on wires instead. Also, Teflon coated wire is both tougher and thinner than the same guage silicon wire and you don’t always need the flexibility.

 

AMP is TE which is what Tyco rebranded to.

In the airplane world, Amphenol is used which is not to be confused with AMP. Two separate and independent companies.

Soldering is OK but there are some caveats.
1. If you do not have complete control of tip temperature, don't do it. It is easy to get solder wicking back underneath the sheathing with an uncontrolled temperature soldering pencil. Now a days Hakko makes reasonably priced stations with temp control that can prevent wicking if done right.
2. Flux is your friend. No, not the built in flux (rosin). I am talking paste or liquid flux. Make sure the flux you use is correct for the solder you use... ie if Solder = SAC305, use flux compatible with SAC305.
3. Once soldered, glue lined heat shrink to stress relieve...

On the crimping front... you can use inexpensive tools for crimping a few connectors but if this is your job. you have to think long term tool investment.

IE Jreedy indent crimpers work for autosport and Deustch DT connectors but if you need traceability, DMC or Rennsteig are the only players.
same with iwiss, wirefy etc. just need to test crimp to make sure you are getting adequate crimping.