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Crimp Terminals for Stranded Wire

daen's picture

I have found a few posts on Breaktime that touch on this subject indirectly, but I wanted to get more specific input.

I am building my own workshop. I am installing electrical now. I got a great deal on stranded wire (#12 THHN). The outlets are surface mounted metal boxes with 3/4" EMT between. Stranded wire for hot, Neutral, and Ground run from box to box. The wiring is just roughed in right now and getting ready to trim out.

My intentions are to connect the splices at each box with wire nuts and add a pig tail for the receptacles. But how to connect to the receptacle with the stranded wire?

I know I can buy the spec grade outlets with the back connections to handle the stranded wire. However, I have available some Hubbell Spec grade outlets with side screw connections only. Price is really attractive (free is good).

Options:

1> Break open the piggy bank and buy the more expensive receptacles

2> Buy some solid wire to make the pig tails for each box and use the side connection receptacles

3> Use crimp terminals with spade/fork tongue ends to connect to the side connection receptacles

Number 3 is what I am thinking right now because I have all the stuff on hand. But my main question is whether crimp terminals are acceptable / good practice for residential. With a proper crimp, is there a concern with electrical performance? I have a good Tyco/Amp ratcheting crimper for PIDG series terminals as well as the typical indent crimping notch on Klein strippers.

Thanks in advance.

Daen

First off, I wouldn't trust (post #194296, reply #1 of 20)

First off, I wouldn't trust the crimp notch on your strippers to crimp paper.  The other crimper might work if you can find the right lugs and the crimper is sized right.  Dunno what the code has to say about it -- I think crimped lugs are legal, but they would need to be UL listed.


Of all the preposterous assumptions of humanity over humanity, nothing exceeds most of the criticisms made on the habits of the poor by the well-housed, well-warmed, and well-fed.  --Herman Melville

Crimp Lug Source (post #194296, reply #2 of 20)

I'll have to check for the UL listing. The lugs are sourced from Belden (NAPA) which should be a reputable brand...

But NAPA parts are designed (post #194296, reply #4 of 20)

But NAPA parts are designed for 12V DC circuits.  Granted, insulation isn't an issue here, but there can be subtle effects that add up over time.


Of all the preposterous assumptions of humanity over humanity, nothing exceeds most of the criticisms made on the habits of the poor by the well-housed, well-warmed, and well-fed.  --Herman Melville

I would use the stranded wire and connect to what you got....... (post #194296, reply #3 of 20)

by cutting the wire, back scoring the end of the wire sheath about a half inch back, pull and twist this small pc ot wire cover not taking it totally off.  This bares the copper, but keeps it in a tight strand.  Wrap that around up and over, tighten screw.  Leave the tab exposed behind the fixture.

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Just connect the stranded to (post #194296, reply #5 of 20)

Just connect the stranded to the device. All common devices are listed for stranded wire.

Greg

These will make things easy (post #194296, reply #6 of 20)

These will make things easy for you:

http://www.idealindustries.com/products/wire_termination/twist-on/term-a-nut_pigtail.jsp

The are wire nuts with a built in pigtail length that ends in a metal U designed to go under those side screw terminals.  What you are paying for is the ability to not have to worry about your capabilities of properly screwing down stranded wire.

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Crimp terminals, for what it's worth... (post #194296, reply #7 of 20)

In a previous life, I did a lot of 12/24/32vdc wiring on boats,  most of them were USCG inspected small passenger vessels, some were repair or retrofit jobs, others were new construction.

As a result of this activity, I still have a v-a-s-t assortment of vinyl insulated crimp connectors which are required on 99.99% of all connections.  All stranded wire since solid wire is strictly prohibited due to vibrational fatigue considerations.

I just went down and checked the "inventory" --- I have crimp (pressure) connectors from about 6 different manufacturers -- what they ALL have in common is a UL stamp on the packaging.  I did not find any Belden's, but I suspect they also wear the stamp.  Worth checking.......

I built an addition onto the back of my own house, 20'x32', just one big open room with 11' ceilings.  I knew this would be used as a workrooom of some sort but was not positive of future electrical needs.  So I ran a 100A sub-panel, pulled Romex into the attic and ended in JB's. out of the JBs - 3/4" PVC conduit to double wall boxes every 6' along all walls. Used #12 solid green for the grounds to facilitate connectons to metallic box ground screws.

Pulled #12 stranded into each box and used crimp connectors to attach to the outlets.  That was 18 years ago, and despite heavy usage and loading, I have never opened an electrical box due to a problem.

I used fork style insulated crimps applied with a "liberated" set of Clark Cable crimpers, they are a ratcheting style that refuses to release until the crimp is full competed, crimp both the actual wire connection and insulation simultaneously, two nests for different wire sizes, seem to have a Mil Spec number on them........

The Middle Department inspector loved them.

I simply made the crimps and yanked hard on the wire -- yes a very few pulled off, due to insufficient stripped wire length - re-strip, re-crimp - yank hard again - connect.  The same test as USCG inspectors suggest during construction - though their test is actually 10 lbs for 10 minutes or some such -- during new construction inspections of vessels they will actually disconnect a few wires and hang their calibrated wieghts for some time period -- if a connector pulls off, I don't know what they do......I'm sure it would not be pretty -- mine never failed during an inspection, I had already corrected any deficiencies during construction.  USCG inspectors can, and do show up, un-announced, at any time during vessel construction - you never walk away from a problem - anything which you are not currently working on needs to be "inspection ready" or obviously not completed.

The fork style terminals are very easy to connect / disconnect under the outlet screws.

Jim

Never underestimate the value of a sharp pencil or good light.

All that said, I'm a big fan (post #194296, reply #8 of 20)

All that said, I'm a big fan of the backwired receptacles and switches.  They're virtually foolproof and a lot easier to wire.


Of all the preposterous assumptions of humanity over humanity, nothing exceeds most of the criticisms made on the habits of the poor by the well-housed, well-warmed, and well-fed.  --Herman Melville

Agreed.... (post #194296, reply #9 of 20)

I like the outlets with the back clamps also.  I never had great luck wrapping #12 around a terminal screw, always ended up cussing at the fly-away strands. Although I did make a mental note of the trick someone posted of stripping and leaving an insulation nub in place on the wire end to keep the strands bundled, wunner how long before that note gets lost.......

However, in his OP, he said that he is inclined to go with the crimped terminals "because I have all the stuff on hand." Including free Hubbell spec grade outlets.

His option #1 was to pony up the addition cash for outlets with back clamps, but he would prefer not to open the piggy bank.

Slick trick a coworker showed me on boats.......There is a crimp connector style called a "closed end connector" which looks similar to a wire nut, available in several different sizes.  Regular wire nuts are a no-no on inspected vessels (steel spring inside = corrosion).  However, you can crimp a closed end connector onto 2 or 3 wires, yank test it, and then shoot the plastic skirt full of silicone and produce a trouble free connection which lasts for years, even in the constantly wet bilge. Bilge pump conections are the most common application.  Butt connectors have a terrible reputation around salt water, and I used the silicone-filled closed end connectors anywhere a butt connector would be "normally" used.  

Jim

Never underestimate the value of a sharp pencil or good light.

Yeah, I've seen the (post #194296, reply #10 of 20)

Yeah, I've seen the closed-end connectors used occasionally in commercial work.  (And of course you see them a lot in appliances.)  I'm guessing the sparkies that use them have a special crimper that can get into tight spaces.


Of all the preposterous assumptions of humanity over humanity, nothing exceeds most of the criticisms made on the habits of the poor by the well-housed, well-warmed, and well-fed.  --Herman Melville

My "liberated" crimpers (post #194296, reply #11 of 20)

are fairly small and will go into a wall box, however, in a switch box, I just use wire nuts.

Wire nuts are cheaper, faster and easier to rework in the future.

Jim

Sun's up, almost 9:00 - time to go to work and make noise.

Never underestimate the value of a sharp pencil or good light.

With a background in (post #194296, reply #12 of 20)

With a background in electronics, I often use crimp terminals, including when I rewired my house.  I use the GB GS--388 8-inchl crimping pliers.  If you have any grip strength at all, they can give you a secure connection with most common crimp terminals.  I also have a similar pair of crimp pliers from another manufacturer, the name of which escapes me at the moment.  With the appropriate crimping tool, I would not hesitate to use the spade crimp connectors on the electrical outlet.  The GB pliers are available from most big box and hardware stores or from Amazon:

http://www.amazon.com/GB-GS-388-8-Inch-C...

  Agreed. I have a pair of (post #194296, reply #13 of 20)

 

Agreed. I have a pair of those, and like them.

I also have a pair of the channellock crimpers.

http://www.amazon.com/Channellock-909-Cr...

I prefer the channellocks.

When connecting two or more wires together, whether household or automotive, I prefer crimps over wire nuts.

For household, I use the GB 10-410 crimp sleeve connectors.

Strip the wires long.

Twist them together, well.

Crimp, test the crimp, then trim the wires.

Cover with the rubber boots made for them. (Getting hard to find those boots.)

Then tape the connection as well.

.

It's a small world. Until you have to walk home...

If ya bother to crimp, use (post #194296, reply #14 of 20)

If ya bother to crimp, use eye terminals vs. forked. 

 

Kinda hard to get the eye (post #194296, reply #15 of 20)

Kinda hard to get the eye onto a staked terminal screw.


Of all the preposterous assumptions of humanity over humanity, nothing exceeds most of the criticisms made on the habits of the poor by the well-housed, well-warmed, and well-fed.  --Herman Melville

Plus, even in the ones that (post #194296, reply #16 of 20)

Plus, even in the ones that don't have that feature, the threads on the screw have often been deformed to keep them from easily coming all the way out and which can make them hard to get back in.  However, a pair of dykes can easily convert the "eye" to a open "U" that can hug the screw closely. 

On the type otulets the op (post #194296, reply #17 of 20)

On the type otulets the op has (just screws), the staked screw easily come all the way out and the threaded portion does not strip, but does reform the screw threads, then reinsert the screw - do it alla the time. 

Agree that the back clamp inserts outlets are dificult to get the screw back in, but then the op would not even need to ask about using crimp anything. 

A lot of extra work, though, (post #194296, reply #18 of 20)

A lot of extra work, though, for no real point.


Of all the preposterous assumptions of humanity over humanity, nothing exceeds most of the criticisms made on the habits of the poor by the well-housed, well-warmed, and well-fed.  --Herman Melville

This all sounds like a lot of (post #194296, reply #19 of 20)

This all sounds like a lot of extra work. What is so hard about twisting the strands up tight and putting them under the screw

 

http://gfretwell.com/electrical/Stranded...

Greg

Yeah, I'm suspicious of (post #194296, reply #20 of 20)

Yeah, I'm suspicious of crimped terminals anyway.  Stranded wire on screw terminals is a problem (a stray strand can cause big trouble), but it's a manageable problem.  (Though, again, I don't know why the industry didn't switch to backwired ten years ago -- the time savings is well worth the slight added cost.)


Of all the preposterous assumptions of humanity over humanity, nothing exceeds most of the criticisms made on the habits of the poor by the well-housed, well-warmed, and well-fed.  --Herman Melville