This is normal. You might be better off getting the larger barreled
variety. The larger ones might allow you to terminate two conductors
per lug (size permitting, of course), though this is usually a desperate
measure based on not enough terminals. Keep things clean, when you can,
then if you need to do maintenance on one item you will not be messing
with something else.
There is adequate space in your meter-main to add another neutral bus.
On Wed, 20 Nov 2013 19:58:37 -0600, Nightcrawler® wrote:
Is the general consensus that lug corrosion is what actually caused the
huge wires to overheat?
What would be other reasons? Or, is that the only reason a neutral would
overheat, when no other wire appears to be overheated?
Then you have to figure out how to connect the second bus to the first one.
What I remember is the set screw looked like it rusted. That suggests
that the screw is steel. Steel has a rather different expansion rate
than aluminum, and thermal cycling can cause a loose connection. Was the
lug rated for aluminum? Expansion rate is one of the problems with aluminum.
What were the instructions for installing the lug? Did the manufacturer
want the wire to be wire brushed and antioxide paste used?
Connections for large aluminum wires are generally reliable if the right
lugs are used.
Could be it wasn't tightened adequately.
Danny knows what an "appropriately sized wire" is?
What I remember is there are a lot of breaker positions in the panel
that are not used, and as a result a lot of neutral bar positions not
used. I don't remember that a second neutral bar is necessary.
It is easy to add a ground bar - there should be a SquareD ground bar on
the label that can be used.
Adding a neutral bar is not nearly as easy. Does SquareD list one on the
label? Can you find a UL listed one? How to connect it?
This is what it looks like:
If it's as simple as a loose connection, once I replace the lug,
it's *still* going to be steel on aluminum, right?
If so, the simple answer seems, to me, to be that I should tighten
the lugs once a year (or so).
Does that seem viable?
Pretty much no one would know.
As to the lug that's rusty, I'd take that screw and wire out, and wire
brush the wire and the lug. Might need to go to the plumbing department
and buy a 1/2 inch fitting brush. Smaller fitting brush if they sell em.
Because of high copper prices, starting about 1965 and going through the
early 1970s aluminum was used for 15 and 20 amp branch circuits. There
were problems with both the wire and devices (switches, receptacles).
There were fires, and as a result there were changes in the UL
standards, twice. The link is about 15 and 20 amp branch circuits. The
recommendations for making connections that are there somewhere, abrade
surface of the wire and apply antioxide paste, are relevant to all
Aluminum has been used for higher current circuits before that, and is
often used now. The connections for 15 and 20 amp branch circuits are
much different than for higher current circuits. Aluminum is quite
reliable in the heavier circuits, like what you have.
I suspect the failed lug was not rated for aluminum, or was not
There are certain fittings to use with aluminum wire. Add those and
you should be good to go. We use AL wire regularly due to the lengths
we need. Sizes range from #4 to 350 MCM. This is outside where
condensation and dirt can be problems. We seldom have problems with the
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