use Alum plate instead of wires

[devittjl]

I have an application where I need to wire two contactor in series (redundant MCRs). They are in line with each other. The wiring connection is a tab with a 1/4-20 bolt/nut.

My assembler would like to use a bolt-on alum plate the same size and thickness of the contactor's alum connection in lue of wire with crimp lugs.

Anyone see an issue with this? Would it turn some heads in both the UL and CE circles?

 

[MikeHalloran]

Not every silvery metal is aluminum.





Mike Halloran
Pembroke Pines, FL, USA

 

[DHambley]

Sounds like a question for an electrician who knows codes of allowed connection practices. Engineers like us would say AL to AL is fine (the electrons don't care) but it sounds like a code issue.

 

[MacGyverS2000]

Is the original connection actually aluminum or plated "other"?

Dan - Owner

http://www.Hi-TecDesigns.com

 

[mcgyvr]

Most contactors I've seen are tin or silver plated copper and not aluminum. Depending on what type of product/standards this is for will also dictate what you can/can't do. For the standards I must follow I can't use aluminum as a current carrying conductor.
This should be decided by engineering judgement and not ease of assembly.

 

[Skogsgurra]

The first problem is that aluminum 'yields' under pressure so that contact force is reduced over time. Worse if load is cyclic (multiple heavy starts). Reduced force/pressure increases resistance and heat developed which leads to an avalanche reaction.

Also, it is not at all probable that your contactor tabs are made from Al. More probably from tinned or plated Cu.

Gunnar Englund

http://www.gke.org

--------------------------------------
100 % recycled posting: Electrons, ideas, finger-tips have been used over and over again...

 

[jraef]

I too seriously doubt your contactor tangs (that's the name for that part that you bolt the lugs onto) are made of aluminum, it would not stand up to the mechanical shock issues as Gunnar says. If they are copper, using Al for connector bars is not a good idea not only for the reasons stated by others but also because Al expands and contracts at different rates from Cu and the connections would need to be checked for tightness more often that normal, which in my experience rarely happens anyway.

Use copper bars instead of Al. You can buy after-market plating materials if you so desire, although it may or may not be necessary. Contactor parts are tin plated mainly because the mfr. has no idea where the contactor may be used, but in many installations it isn't all that necessary.


"If I had eight hours to chop down a tree, I'd spend six sharpening my axe." -- Abraham Lincoln
For the best use of Eng-Tips, please click here -> faq731-376