crimp ends

No problem, perfectly acceptable.

when you crimp smaller wires into a larger fixture you must take care that you do not over crimp and crush one of the smaller wires to the point where you cause a current concentration.

Modern crimps are called "gas tight" and are made to progressively make contact and squeeze out air to make a metal to metal contact. This does not work with two wires and in time at full rated cirrent with slight heating you can get progressive oxidation. This reduces the cross section and it then runs hotter and you have + feedback to failure. If you are running at low levels of current this will probably not happen,.

Its acceptability depends on local standards. Doing this inside an EEx e terminal box, for example, would place the box outside the hazardous area certification standards.

if they are locking crimps why not use piggy back crimps (Receptacle/Tab Combination Crimps) Try this link.

http://catalog.tycoelectronics.com/TE/bin/TE.Connect?C=122&M=FEAT&P=139441&U=&BML=10576,17560,17698,17703&LG=1&I=13&G=G

No. Terminators are designed for the wire size listed on them. Putting in smaller wires will not put enough pressure on the wires.

I personally don't like this. Your main concern should be the end product quality requirements. It is however, an acceptable practice in many places, but usually for much larger section conductors. If you are looking for a high quality long lasting connection vibration proof and so on, than don't do it, If you decide to do it, than use a filler to increase the overall conductor's diameter to the crimp size.That is a short pigtail inserted together with the smaller wires, end ends at the end of the crimp. I would also run some tensile strength and electrical resistance tests prior to any sizable production. Last solution, could maybe the use of different size ferrules these are crimps with different awg sized in each end. I remember seeing them long time ago they were made by AMP, Ideal, and 3M.

Hope it helps.

Wangito.

I just got done making another T harness to attach instrumentation to an existing harness. Two 22AWG wires into a 20AWG pin. According to the pull gauge it works fine.

This works very well with Deutsch connectors.

What I do is strip 2x the normal strip length of each wire. Then I fan the wire strands of each wire so that the strands are fairly well seperated and kind of flat, like a Japanese fan. I hold the wires so that the fans of each intermesh and then twist the strands together. Then I trim to the length necessary for the pin. Insert and crimp.

In some cases you can run into a problem where the diameter of two wires with insulation won't fit into the slot in the connector shell. AMP and Delphi connectors can fall into this catagory. In that case I strip off more like 3x the insulation length, twist the lot together and then use heat shrink tubing to "re-insulate" the wire back out of the connector shell.

Of course you have to be sure that the current in the OEM harness isn't such that you're going to have a heat problem. But for sensors this isn't a problem.

This won't work in a wet environment all that well unless you take extra precautions (lots of silicone sealant) in the connector to keep the water out.

www.molex.com has an excellent section on what a good crimp looks like. There are several variables involved in crimping such as stripping, nicked strands, crimp height and pull testing. If in doubt about the quality of 2 wires Crimped then also solder the crimp.

It is acceptable to crimp multiple wires into a connector as long as the connector can handle the equivalent wire size of wire bundle. This is covered in section 19.11 Crimp Slices in http://www.hq.nasa.gov/office/codeq/doctree/87394.pdf NASA-STD-8739.4 CRIMPING, INETERCONNECTING CABLES, HARNESSES, AND WIRING. This is a good overview on how to specify, make and inspect wire harness.

It all comes down to what you expect from the connection: If it is to help you out of a difficult situation you can perfectly do this.

If it is for a series product you will have to qualify your solution.

The basic standard that you can take on this subject is: IEC 60352-2:2006

In theory a crimp is for one cable /barrel, if you want to go for more than one cable you need to take the full release schedule.

Don't let you be scared on terms as gas tight and other magic terms: gas tight is a term with different definitions and reasons. It all is based on the idea that when the contact faces are not subjected to oxygen, the connection will be guarantied.

You may want to check out 3M Solder Splice connections for multi wire connections/splices.