Terminating stranded wire on a circuit breaker

[brantdavid]

I am terminating a #12 awg stranded wire on a Siemens QP type circuit breaker installed in a load center. The QP breaker has a screw type terminal. When making this connection some of the wire strands will push out from under the screw. The result is an inferior connection.

I could tin the wire or install a ferrule. I would appreciate any comments or suggestions on the proper method of termination david.brant@tycoelectronics.com .

 

[charlie b]

Re: Terminating stranded wire on a circuit breaker

Tinning would obviously make for a better connection, but it still might not be the right thing to do. I suggest starting by contacting Seimens, to see if stranded wire is acceptable for use with their breaker.

 

[rick5280]

Re: Terminating stranded wire on a circuit breaker

You could also strip off about 1" of the insulation, pull that off, then strip off about a 1/4" piece of the insulation, and slid that to the end of the wire. A few twists, and a loop, and presto! you have a "contained" wire, ready for termination under a screw, looping the wire around the screw.

Check to make sure the termination is approved for stranded first.

Rick Miell

[ September 30, 2003, 01:28 PM: Message edited by: rick5280 ]

 

[curt swartz]

Re: Terminating stranded wire on a circuit breaker

I have had this discussion with Siemens reps before and they say that stranded wire works fine with their circuit breakers. I disagree. The screw will grab a couple of the strands but pushes most of them aside. I feel this is a very poor design and don't know how it ever got though UL.

Rick, there is no way to wrap the wire around the screw. They are like the terminals on most small breakers. You place the wire in the hole and tighten the screw. The big difference is that there is space around the screw in the terminal and on most other breakers either the screw fill the entire terminal or there is a pressure plate to hold the wire.

 

[Guest]

Re: Terminating stranded wire on a circuit breaker

Hmmm...
Sounds like bad engineering. Can you flat tin it? Sounds like the only viable workaround. Or, can you solder on a spade connector?

 

[tonyi]

Re: Terminating stranded wire on a circuit breaker

The easy way out...splice in a short length of #12 solid, torque to spec, and call it a day

 

[Guest]

Re: Terminating stranded wire on a circuit breaker

I've wondered about splicing on in a panel. Does that make the panel into a junction box, or is a splice not considered a junction? You gotta do what you gotta do but when does a panel become a junction box? Where is the line drawn? Thanks!

../Wayne C.

PS: I only edited this to add my signature. When I preview my post my signature is there, but 50% of the time it does not stick. Any ideas on what's up with the signature?

[ October 01, 2003, 11:29 AM: Message edited by: awwt ]

 

[dereckbc]

Re: Terminating stranded wire on a circuit breaker

Is it possible to use a compression terminal?

 

[don_resqcapt19]

Re: Terminating stranded wire on a circuit breaker

Wayne,
See 312.8 but make sure that you read the complete section. Most stop reading at the end of the first sentence.
Don

 

[roger]

Re: Terminating stranded wire on a circuit breaker

T&B, Panduit, Ideal, Illsco, etc... all make these.

Part #
KN10-14PT-D for 12-10 A.W.G


We use these and more specific types in PLC's.

Roger

 

[tonyi]

Re: Terminating stranded wire on a circuit breaker

Originally posted by don_resqcapt19:
Wayne,
See 312.8 but make sure that you read the complete section. Most stop reading at the end of the first sentence.
Don

Indeed, they key thing being "unless adequate space..." As a practical matter, almost any panel with mostly 15/20A branches should meet the % limits. Even a rats nest might looked stuffed, but in reality there's a lot of empty cross sectional area between the individual pieces of spaghetti.

 

[templdl]

Re: Terminating stranded wire on a circuit breaker

dereckbc.

Is it possible to use a compression terminal?

It depends upon the manufacturer of the breaker. Remember that the terminations play an important part of conducting current to and from the breaker. If done incorrectly the termination could add heat to the breaker causing the breaker to derate which often is a cause of nuisance tripping and also the possibility of damaging the insulation on the wire.
Some manufacturers offer provisions for ring tongue terminals which are listed by UL for that application.
In addition, a word of caution with regards to the home made solutions of bolting the connection with a steel nut and bolt. The current will heat the nut and bolt an it passes through the connection.

 

[roger]

Re: Terminating stranded wire on a circuit breaker

Templdl,

It depends upon the manufacturer of the breaker. Remember that the terminations play an important part of conducting current to and from the breaker. If done incorrectly the termination could add heat to the breaker causing the breaker to derate which often is a cause of nuisance tripping and also the possibility of damaging the insulation on the wire.

can you provide some direct wording from a manufacturer to this and precisely which manufacturer would object to the "pin" connectors I showed?

We know terminations are critical to circuits and can not be made haphazardly

Roger

[ October 01, 2003, 08:18 PM: Message edited by: roger ]

 

[dereckbc]

Re: Terminating stranded wire on a circuit breaker

templdl, I work on a lot of low voltage DC, high current applications. In that line we use only stranded conductors and compression connectors. The reason for this is the low resistance properties of the combination. I am referring too T&B , Burndy ring, spaid, and tounge connectors, which are UL listed for the purpose provided proper installation procedures and tools are used.

IMO if stranded wire is used, a compression terminal is the best method (lowest resistance, secure) to use. I base this statement on numerous thermograph images as compaired to solid wire terminations on a screw or mechanical terminal.

In addition, I also require compression connectors on all AC conductors larger than 6 AWG, rather than a mechanical or screw type terminal in my designs. Call me nuts

 

[big jim]

Re: Terminating stranded wire on a circuit breaker

I think the compression pins would be the preferred way to terminate stranded wire. The key is proper installation. Like almost everybody, I've used the the crimping jaws on the cheap multi purpose tools a lot. I recently purchased a real crimping tool and I am amazed at the difference. I'm sure I'll use crimp-on connectors more often now that I have confidence in their installation. Basically, I refuse to wrap a stranded wire under an ordinary screw head. The only drawback I see to compression connectors at all is the cost of the tooling.

 

[dereckbc]

Re: Terminating stranded wire on a circuit breaker

Big Jim, you are correct about the tooling cost. For example the T&B ERG-2001, TBM-25, and WT-2130 are in the $250 price range. Once you move up into the larger wire sizes the tooling cost quickly go into the thousands.

If you are going to use stranded wire with compression connectors you should use listed terminals. If you use listed terminals you have to use the tool listed for the terminal in which you are using. Unfortunately the tooling will be expensive, but as you stated makes a world of difference in the quality of the connection.

In fact the testing I have seen done is the tensile stregth test in which a wire is terminated in a terminal. The wire will break before the wire is pulled out of the terminal.

The listed tools will also leave die impressions on the barrel or on the insulation so it may be inspected to determine if the right tool was used.

 

[templdl]

Re: Terminating stranded wire on a circuit breaker

roger,
The termination on a breaker are tested with rated wire. If I can recall correctly the terminals themselves are listed UL486(?). If one were to stick to the "Letter of the law" the terminals and the terminals with breakers as listed UL 489 would have to include those "pin" connectors. If a manufacturer would allow the use of "pin: connectors then they must be included in the UL listing procedure. Of course there is this possibility that the "pin" connector manufactures may have had their product listed to transition from stranded cable to terminate as would solid.

dereckbc, Good practice. The only gray area is if steel bolts are used the steel could heat because of inductive heating. Again, it is best to use the adapters as supplied for your application by the manufacturer. I have a 250a frame breaker that I keep as an example of the misuse of terminating stranded wire. It illustrates where one terminal fails, the heating and cooling progressively loosens the terminal, the terminal gets hotter. As the termination continues to loosen arcing takes place within the terminal. More heat is generated which breaks down the barrier between it and the phase next to it. Then, a phase to phase arc fault occurs. The air is ionized and the arc now escalates to include the ground. Not a pretty sight but a good example.

 

[big jim]

Re: Terminating stranded wire on a circuit breaker

dereckdb: I was actually looking at crimpers because I do a fair amount of auto electrical. I had always been scared off by the multi-hundred dollar prices until I discovered eBay. The crimpers I got are T&B (don't remember the number) with 4 sets of dies for insulated and bare yellow, blue, and red for about $30. There seems to be a lot of that kind of thing being auctioned off now. A company can't afford to mess around with it but an individual buying his own tools can save some big bucks (should I mention my $60 Milwaukee Hole Hawg?).