terminal strips

ws9876ws9876 Solar Expert Posts: 424 ✭✭✭
edited July 2018 in PV Installers Forum - NEC, Wiring, Installation #1
I have a 7 position terminal strip block for joining wires.Typical black plastic cube that you see in many electric devices. It came out of a controller service box 240 v that stated on the outside that you should use only copper wires. But the metal in these terminals looks like alum and when I scratch the metal I dont see any copper color. The threads on the screws dont show any copper also. Do you think the metal is alum???
If so is it a bad thing to join 2 copper wires in one of the terminals if it is alum???There was only copper wires,6-10 gauge  in this service box when it was in use and there wasnt any problems..what do you think??
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  • mcgivormcgivor Solar Expert Posts: 3,854 ✭✭✭✭✭✭
    #2
    The terminals are likely an aluminum alloy, if they were specified for copper only, it's likely the design of the set screw which dictates what conductors can be used. Regarding putting multiple conductors in a single mechanical terminal, this is bad practice, terminals are designed for a single conductor within a specified range. Some reading material on terminals you may find informitive http://www.ecmweb.com/content/copper-or-aluminum-lugs-how-should-you-decide
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  • mike95490mike95490 Solar Expert Posts: 9,583 ✭✭✭✭✭
    #3
    If the strip is rated for Ring or Spade terminals, you can usually stack 2 per screw. But maybe what you call a "terminal strip block" is not what I am thinking of as a terminal strip:

    and there are little U shaped jumpers you can use to join more pairs
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  • ws9876ws9876 Solar Expert Posts: 424 ✭✭✭
    #4
    I guess its ok. Franklin Electric knows what they are doing.
    "The thermal expansion properties of copper and aluminum dictate that installers use only aluminum-bodied lugs to terminate aluminum conductors. Likewise, installers can use copper- or aluminum-bodied lugs to terminate copper conductors."

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