View Full Version : Welding Cable Lug connectors for Moly

Dave Hilty
04-15-2012, 07:12 PM
Detected (by smell first coming from the transformer cabinet) one of the secondary transformer connections over-heating and confirmed with the IR temp. sensor that the one in question was reading 350 D.F. versus it's brother at 120 D.F.

Last time this happened I ignored the now familiar smell coming most likely from overheating cable insulation near the connector and this resulted in a melt-down of the aluminum lug.

Stopped at the Elect. supply house for replacements and the guy at the counter said that I'd be much happier with a copper lug w/ stainless set screw versus the aluminum one that has an aluminum set screw. Try to get the aluminum allen screw out once it's welded on to the cable and it strips out leaving no option but to cut it off.

My question is "is there some reason we should not use copper over the supplied aluminum lugs"? The aluminum will melt under corroded conditions potentially dripping melted aluminum into the transformer (This well-covered by Pete in previous discussions). I know the aluminum is cheaper than the copper lugs but is there a reason why I shouldn't just switch them all to copper?

Steve Stadelman
04-15-2012, 08:22 PM
Dave, if they are the truly expensive solid copper ones they are great. Go ahead.

Pete VanderLaan
04-16-2012, 03:14 PM
Otherwise I have the heavy aluminum ones in the shop. I highly recommend keeping one spare. You 're right that once it has overheated, its gone.The copper ones can melt down too.

Dave Hilty
04-16-2012, 09:33 PM
Bought a couple of the copper connectors to try and see if they maintain better than the aluminum. Anti-oxidation compound is recommended for either but I did a little poking about for comparisons between the two and it seems that less ongoing maintenance of copper connectors is required in comparison to aluminum due to lower COE of copper and the oxides and sulphides of copper are conductive while the same oxidates of aluminum are not conductive.

Rollin Karg
04-16-2012, 09:53 PM
Dave, are you cooling those connections ?

Dave Hilty
04-17-2012, 09:20 AM
Rollin, This is the small Moly (and perhaps one of the last shipped by Brent before the end. It's configured with the 100# power unit rather than the smaller original config. for the 80#er so I can get quicker recovery during charges. As I understand it, they never shipped these smaller units with any cooling gear.

Are you suggesting this might be a good investment?

Rollin Karg
04-17-2012, 02:18 PM
Rollin, Are you suggesting this might be a good investment?

Yes, all of my transformers have their own dedicated blower. We cut a hole in the front of the transformer and have a blower aimed right at the lugs and then the air passes over the coils. I consider it insurance. Between this blower and the one on top of the furnace we are keeping all of our connections cool. We're not melting connections and we're not spending a lot of time tightening things up.

Pete VanderLaan
04-17-2012, 03:12 PM
The last two Charlie and I built just have two squirrel cage blowers on top, facing down and that is really simple and really works. I put a squirrel cage on the transformers as well and they run stone cold all the time.