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Old 06-24-2011, 12:20 AM   #1
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Default MARR connector

Back in the mid 50s some genius at MARR decided wirenuts weren't a good enough connector in industrial work, particularly motor connections so they invented this brilliant device.

After disassembling the deviece, the stripped wires are inserted into the brass barrel, and the setscrew is tightened down. The insulating cap is then threaded onto the barrel and the job is forever done without any maintenance problems in the future. Being a generous company MARR even provided a handy plastic handle for large fingered electricians to hold the barrel in while inserting the wires and tightening the setscrew.
That's how the propaganda went. In the real world using these handy devices was a little different.
1, grab a pocket full of the damn things
2, try finding enough that actually have the setscrews in the pocketful you're carrying.
3, screw around 3 times longer than it would have taken to install lugs and a bolt.
4, grab another one and try over because your pliers screwed up the thread on the barrel and the cap won't go on
5, send the helper back to get more connectors because the setscrews are all lost
6, be really careful to not strip[ the thread on the last complete connector so you can finish the motor changeout and get the plant foreman off your back.
7, wrap the damn thing with tape so the insulator cap doesn't come off and blow a hole through the side of the motor connection box.
8, close box and energize motor to check direction
9, locate mortor starter and swap 2 wires so yo don't have to go through the nightmare again.

MARR Connectors came in 2 sizes. Neither was popular with electricians. Purchasing agents seemed to love them though. I'm not sure when they quit making them, but it wasn't soon enough.
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Old 06-24-2011, 12:33 AM   #2
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They never quit making them. You can buy them brand new from Ideal to this very day.

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Old 06-24-2011, 12:42 AM   #3
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I had a service call in a house that was filled with those things. First time I ever saw them. I actually kind of liked them.
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Old 06-24-2011, 01:29 AM   #4
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I had a service call in a house that was filled with those things. First time I ever saw them. I actually kind of liked them.
Yeah, they were pretty darned popular for a spell. There are certain occasions where I'd still use them if I ever bought any. A small motor would be one for instance. A 480 motor up to maybe 15 horse, probably, or any small motor on 208-240. Just as good as a split-bolt, with a screw on insulator. I'd never wire a whole house or office/retail space with them like the old timers did... misery.
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Old 06-24-2011, 06:33 AM   #5
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They used to be code here for anything 347/600V.
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Old 06-24-2011, 07:57 AM   #6
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When I started in the trade back in the 70's, the guy I was working for used the Marr connectors to connect fixtures and the Buccanan four way crimp sleeves with the snapon covers for all other splices. Sometimes we ran across some Buccanans that had rubber sleeves with a red retaining ring or a diaper type that you had to stretch between the wires and loop over the splice.
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Old 06-24-2011, 09:22 PM   #7
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They never quit making them. You can buy them brand new from Ideal to this very day.
I think I have a package lying around somewhere, they are listed as vibration proof or vibration resistant.

Yeah at the hydro plant I was in last year they were specified in the contract, and that building did nothing but vibrate with all those 30MW generators running. Felt like an earthquake when they'd open the gates to start one up and I guess I can see the reasoning for wanting them there.

Now that I know they're still on the market, I think they'd be great for some applications involving motors or other locations where the joints would be subject to constant or heavy vibration...

...they are very expensive though.
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Old 07-06-2011, 11:40 PM   #8
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At one time that was all that the Ma and Pa local hardware store's sold. I run into quite a few diy installs of these things, can pull them ff by hand most would use electrical tape to hold them on
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Old 07-07-2011, 12:01 AM   #9
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These are actually in the specs on our job site, although they don't enforce it. When I was an apprentice, they did enforce it.

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