That a Marr connector.

Now they come with a Roberson screw head

Doug,

Were they used where vibration was an issue? Like I said, I just heard them called "Vibration" wire nuts but no one could give me the right name. Till now.

twh,

is Marr a trade name or just a style of connector?

I think it's the name of the inventor. The company that made the original Marr now makes the Marrette wire nut. By now, the name might be like kleenex is to facial tissue, but I'm not sure if anyone else makes that type of connector. When I went to school, they had specific instruction on not twisting the conductors unless one was stranded and the other solid.

And remember to put the thread on first towards the insulation, otherwise the cap doesn't screw on far enough to cover the bare wires.

I think it's another Canadian thing.
They are still available and sold as anti vibration.

http://www.tnb-canada.com/en/catalogues/online/comresconstruction/pdf/c5/01_marrcat_e.pdf

I was going to say that only my northern neighbors seem to know about this type of wire nut. I never saw lots of these connectors but I was out in the field from 1976 to 1998 and I think I only saw maybe 2 dozen or so.

Harold, I've never installed one and I've been around as long as you have. A couple dozen is about the same number that I've run into, too. To add to jdevlin's point, some of them were backwards.

I think a vibration wire nut is a normal wire nut tightened with pliers.

Looks like someone crossed a wire nut and a European "choc block" style connector

They preceded wire nuts with the spring. We still see them but are not very common any more. A better connector where vibration was an issue but the caps have been seen to loosen too.

A customer happened to give me an old box of marrettes today

Interesting about the wire mixture , that was a new one to me

Doug:
Are those still available? The wire mix is really interesting to me. The word 'approved' is from a NRTL or is that the mfg choice?

They do not bear that wire combination anymore on the new ones. but if you look at jdevlin link from above Marrette now has # 63 and # 65 connectors that are certified for that wire combination.
oh here is a direct link

http://www.tnb-canada.com/en/catalogues/online/comresconstruction/pdf/c5/09_marrcat_e.pdf

Doug:

Thanks for the link!! I notice the 'not UL', but a 'CSA'
The only al wirenut I have seen is the Ideal Purple around here.

I remember seeing those setscrew connectors at the local hardware store when I was little. I only seen one once in the field, and that was in a motor's terminal box. Funny thing only one connection had the setscrew connector, the rest had wirenuts.

I know they list them in the current ideal catalog.

I tried to go out to jdevlin's web page, but I couldn't get through. It said the "file was damaged". Maybe I can search for it in another way.

TWH,

Even though I have been around electrical work for 30 plus years, and all the guys I talk to at the supply house, many have seen these types of wire nuts but few actually use them. The other thing is that you don't see them every day. You can go for months and and even a year or two then you see them again.

Doug,

I know that you have an old box there but I was just wondering, Are the still listed to use with AL to CU wires?

Not that part # anymore
the new revised marrette is a #63 and a # 65 for al-cu
not sure what year they changed that.

Compare these connectors from down this way:



We've always used screw type connectors down here with everything from domestic wiring up to industrial stuff that doesn't require lugs and what-not.
BTW, if anyone collects connectors and would like one each of these, send me a PM, I have zillions of them.