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Electrical Connections
13 questions By Tony R. Kuphaldt
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Question 4 of 13
What is a terminal block, or terminal strip? How are these devices used to make electrical connections between different conductors?
Reveal answerTerminal “blocks” or “strips” are rows of short, metal blocks with screws or other fastener devices used to make firm mechanical bonds to conductors:
Sometimes, terminal blocks also go by the name of “barrier strips.”
Notes:Be sure to have a variety of terminal blocks available for your students to see and touch during discussion time. Terminal blocks are widely used in industrial applications, for making permanent and semi-permanent connections.
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Question 5 of 13
What is generally considered to be the maximum number of individual wires that may be attached to a single terminal on a terminal block?
Reveal answerTwo wires per fastener, maximum:
Notes:I’m not sure if there is a specific code or regulation governing the number of terminals connected to a terminal block, but the “no more than two wires per lug” rule makes good sense. That is, of course, unless two conductors stuffed in the same hole would exceed the maximum cross-sectional area limit of the block, then “no more than one wire” is the rule.
I have had the misfortune of seeing egregious violations of both rules in my work experience!
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Question 6 of 13
Wire nuts are special electrical connection devices commonly used in residential power wiring. Describe what a “wire nut” is and how they are used to make connections between wires.
Reveal answer“Wire nuts” are electrical fasteners which use a coiled spring to clasp bare metal wire ends together. The “nut” is screwed on to the ends of two or more wires to be joined, as though it were a nut being threaded onto a bolt. The coils of the spring inside the nut function as threads, which grip the wire ends tighter as the nut is turned clockwise over them.
Notes:It would be good to have several sizes of wire nuts available in the classroom for your students to see and touch during discussion.
