Breaker lugs too small for wire?

Status
Not open for further replies.

David40

Member
I am curious about the best way to deal with this situation. Lets say you have a 125 Amp circuit and because of the length you end up with 2/0 copper wire. The 125 amp circuit breaker lugs are not big enough to accommodate wire that large. I've encountered jobs where someone has just trimmed off enough strands to make it fit but I don't think that would pass inspection. What would be the acceptable method for dealing with that?
Thanks
 

iwire

Moderator
Staff member
Location
Massachusetts
They make listed crimps that will work. You crimp it on and the other end is reduced in size to fit the breaker.
http://www.tonesties.co.uk/copper_tube_lugs.htm#reducing pin

Often called 'Pin Adapters' you can get them straight, 90 degree and with offset pins. When they work they are a great solution. The problem with pin adapters is they often hit each other because the breaker lugs are not far enough apart.

They also will only drop a size or two.

Pin%20Terminals.jpg


For a 125 amp breaker I would proably use a set of splicer reducers like these......
Splicers%20Reducers%20(Dual%20Rated).jpg

....inside the panel to reduce the wire size.


No hydraulic crimper needed.
 

jwjrw

Senior Member
I have only used the adapters 1 time and in my situation 225a with 350mcm
they worked great.
I'm sure in other situations what iwire suggests would be better.:D
 

iwire

Moderator
Staff member
Location
Massachusetts
I have only used the adapters 1 time and in my situation 225a with 350mcm
they worked great.
I'm sure in other situations what iwire suggests would be better.:D

You are right, they are a great solution in many cases. :cool:

FWIW A lot of the jobs we due that use aluminum feeders the engineer will specify pin adapters at all terminations so we do not have AL under a mechanical lug.
 

jwjrw

Senior Member
Have the UL listing for them handy... I had to show that inspector even though it said UL listed on them.:D
 

cadpoint

Senior Member
Location
Durham, NC
Another company is Ilsco, there catolog M 107
The Solution Book, Electrical Connectors ans Accessories,

It can also be seen on-line. pg 62 the pins start
 

David40

Member
Thanks for all the replies.
No easy way to add a larger breaker. If a splice is OK then reducing the wire size with a wire connector would be the way to go in this situation.
I love to use those pre-insulated Polaris connectors. Expensive, but quick. Just strip, insert, tighten, plug in the caps, and your done no tape necessary.
 

jaylectricity

Senior Member
Location
Massachusetts
Occupation
licensed journeyman electrician
So let me get this straight. If you need to upsize the wire to 2/0 for the run because of its length, it is OK to reduce the size of the conductor for that six inches or so near the breaker? Is there less current flowing through the conductor near the breaker?
 

David40

Member
So let me get this straight. If you need to upsize the wire to 2/0 for the run because of its length, it is OK to reduce the size of the conductor for that six inches or so near the breaker? Is there less current flowing through the conductor near the breaker?

Not sure I understand what you are saying but I'll try to answer. No, it's a 125 Amp max circuit with a 125 Amp breaker. The normal conductor size for that would be a #2 THHN so that is the size I would be reducing to. Therefore the current flowing through both the 2/0 and #2 conductors would be the same up to the capacity of the breaker. The 2/0 serves only to reduce voltage drop by offering less resistance. The voltage drop rule of thumb I have always followed is up one size for every 100' of run.
 

AV ELECTRIC

Senior Member
So let me get this straight. If you need to upsize the wire to 2/0 for the run because of its length, it is OK to reduce the size of the conductor for that six inches or so near the breaker? Is there less current flowing through the conductor near the breaker?

So your saying by reducing the wire size with a splice you would be in violation interesting.
 

David40

Member
I don't know, that's why I'm asking. Generally I try to avoid any splices in a panel, I think they look tacky and unprofessional. When I do a panel I like to leave it looking like a work of art. I'm just wondering if I'm going to get any static from an inspector about it. It's been my experience that when it comes to dealing with any government officials you are at the mercy of their individual personalities with practically no consistency from one to the next. I just thought I would try to get a general consensus of what's acceptable or prohibited in this situation.
 

NewOnMyOwn

Member
Location
NJ
So let me get this straight. If you need to upsize the wire to 2/0 for the run because of its length, it is OK to reduce the size of the conductor for that six inches or so near the breaker? Is there less current flowing through the conductor near the breaker?

As long as the resistance of that 6 inches of smaller wire is less than the resistance of that whole run of 2/0, it doesn't matter.
 

AV ELECTRIC

Senior Member
Im not sure what is the difference between trimming the wire and putting a splice in your reducing the wire size to fit the lug . I believe you can special order a breaker with bigger lugs ime not sure on your time frame it may be worth asking I agree its not very clean and the inspector may not approve but once again you can ask .
 

mivey

Senior Member
Im not sure what is the difference between trimming the wire and putting a splice in your reducing the wire size to fit the lug ...
Other than one is allowed and the other is not allowed, trimming the wire creates discontinuities and greater disturbances in the power flow. Missing strands can be detected with ultrasonic testing. There are certainly discontinuities at a connector, but they tend to not be jagged edges. Jagged ends could be a source for noise and local arcing in some cases.

As for a regular sized cable and considering the safety factors in the cable ratings, I doubt one would notice a strand missing that accounts for only a few percent of the cross sectional area, like 1 strand in 19 or something, but I would think 1 strand in 7 would be noticeable and maybe even significant.
 
Status
Not open for further replies.
Top