Blue vs Yellow crimp connectors

I have a question, maybe one I will regret asking. :slight_smile:

The yellow crimp connectors have #10-#12 marked on them, and the blue have #14-#16 marked on them. Is this based solely on the size of the hole for accommodating the wire, or is it based on current ratings. I have looked up several on the web, and it seems to be related to size, since I didn’t see specs for current rating.

So, if using #12 wire from PDB motor controller, is it ‘legal’ to use blue connectors if they fit and crimp tight? Or can that get flagged as illegal during inspection?


It’s the same contact area whether it is blue or yellow, so it shouldn’t cause any problems.

To get a strong and robust crimp, you should use the correct size. In a pinch you can use the wrong one, but keep an eye on it and do a proper pull test after crimping.

The color is a convenience for installers to easily tell which terminal to crimp on which size wire. The tolerances are such that they can crimp stranded or solid wire in the range. Some terminals will also have the screw size imprinted on them. So if you find a blue terminal with a “#6” on it, the opening is for a #6 screw.

Use the proper terminal. Using to large of wire can lead to failure, will it work in a pinch, yes, good habit to get into no.

As to the current ratings on crimp it’s more of a gray area then black and white. Quality terms are tested to a particular UL standard. and blah, blah they test that the proper connector will run cooler then the conductor at the rating of the conductor.

There are limitations but for our FRC purposes the proper crimp for the conductor will handle the load, ie a yellow ring on a #12 will handle 40 amps.

Thanks all -
We did a large batch of wiring today and wound up accidentally using blue on #12 for the most part. I guess we will find windows of time to recrimp with yellow as we see fit.

I have another dumb question -
What’s the best terminal size for the motor controller screws? According to IFI’s Victor 888 site, the screw is a 6-32.
However #6 spade connectors appear to be awfully small in surface contact area. The units we have been using don’t seem to have screw size numbers on them, just wire size.

I’d like to order a bunch but don’t want to get it wrong, was first thinking #8’s, but according to the data for Victors, should I go for #6 spade connectors?

Thanks again for everyone’s great inputs!

Depending on the manufacturer of the crimp lug, you may or may not be able to get a 12 AWG wire to fit into a blue crimp lug.

On page 8 of Tyco’s catalogue, they give current ratings that are in line with the current ratings for the wires that the crimp lugs are designed to fit. These lugs are designed to meet the requirements of various safety agencies such as UL. I have never had to look into the UL standards for these components but they generally include detailed test conditions that take into account the intended usage. What helps the “small looking” lug meet these requirements is the heatsinking effect of the metal the crimp lug is attached to.