(ET) Ring terminals for high currents

["Geoff Rich" <grich firstsolar com>]

Hi Folks,

I have previously used Thomas & Betts lugs (54XXX series... like ring
terminals on steroids!) on some high current DC circuits.  For example,
they're on the 4/0 cables from my battery bank to the inverter breaker
(250A) in my solar electric system.  These are solid Cu with tin plating,
and they are a constant width back to the barrel.  Actually, I think they
are really a thick Cu tube that has been pressed flat on one end and then
punched out.

I don't know the bolt size on the universal posts, but the traditional 
T-105
posts have 5/16" studs sticking out the top.  For example, if you were to
connect a #4 wire to a 5/16" stud, you would use T&B part #54139 (Grainger
part #3LL61).  The part with the hole in it is .610" wide and .070" thick.
I have replaced the "jumper" wires that go between adjacent batteries with
short cables (more like buss bars, they're so stiff!) made of #2 stranded
cable, with T&B lugs on each end.  No heating problems, but since I
installed them on the standard T-105's, I had to raise the seat by about
1/2" to clear the bolts.

The only problem with these lugs are the cost (~ $1.50 each!) and the fact
that to crimp them right you need the T&B crimper (~ $200).  I happen to do
alot of work with DC systems and therefore large wire gauges and 
connectors.
The lugs and crimping tools are common in the trade, and are carried by
Grainger, as well as most electrical supply houses.


Geoffrey Rich
First Solar, LLC
phone 419-872-7661
FAX   419-872-7665
e-mail:  grich firstsolar com