Energy Off Grid

WHY QUALITY LUGS ARE IMPORTANT

Having bought our fair share of lugs over the years I thought I'd share why I recommend pausing for two seconds and ensuring you're buying a quality lug.

The image attached shows 3 cable lugs. All are 50mm2 with an 8mm opening. The one on the left #1 is from a local electrical supplier, the middle one #2 from an auto parts store and the right one from E-bay #3.
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On face value the all look like they'll do the job but when you pick them up the difference is significant. Both 1 and 2 feel weighty and solid, whilst 3 is significantly lighter.

Throwing a pair of Vernier calipers over them tells a story. Lugs 1 & 2 come in at 2.7mm thick over the terminal end with the E-bay one coming in at 2.2mm. Weighing them also tells a tale with lug 1 coming in at 19 grams, lug 2 at 17 grams and lug 3 at 13 grams. Whilst I'd expect 1 to be the heaviest having the longest cable entry, number 2 and 3 have a difference of nearly 25% for a similar lug size. That's a lot of missing metal.

Why does this matter? Well both of the quality lugs 1 & 2 when used with a 50mm die in a hydraulic crimper created a crimp that easily supported me when I bolted it to a rafter and swung from the cable I'd attached them to. Lug 3 however created a crimp that could easily be pulled apart by hand. In-fact to effectively crimp it required the use of a 35mm die which then over-crimped the lug causing material to be squeezed out from the sides of the die. In effect a poor quality crimp resulted.

When we consider that these lugs often are a single point of failure carrying hundreds of amps I'd say they play a pretty vital role in our off-grid systems. Having been guilty in the past of using cheap lugs and having seen first hand the effect of poor crimps, excessive heat generation at best and termination failures at worst, I'd definitely recommend hunting down quality lugs.