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Component Compatibility Answered

What do I look for when trying to find components that work well with each other? For example: If I have a 120V, 6.5A motor; how do I know what type of on/off switch to use?

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11010010110Best Answer (author)2009-02-24

voltage should match current should match with some safety extra. fo example for 6.5 A motor use atleast 8 A switch some motors tend to arc in the switch when switched on. if thats the case use a switch for higher A. switches that make loud and more powerfull-sounding click tend to arc less switch with higher V or A is atleast as good or better for copper wires the max load acceptable is 10 A / mm2 when in open air and 7.5 A / mm2 when in cable or duct you can overload about 1.5 X when its for short time only or about 2 X if there is fan that blows cool air on the wires local regulations may require lower currents for wire of the same thickness as with switch - thicker wires are atleast as good you should use wires for sufficient voltage too so the isolation does not break down (allthough 110 - 240 V is not enough to be a big issue with most cables. i often use red smoke detector cable designed for 12 / 24 V at 240 V. it is against the code but the isolation in this wire is visibly thick enough to stand this voltage)

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luch (author)110100101102009-02-24

Thank you for your quick response! Would it be acceptable to use a standard wall switch (120v, 15amp) or is 15 amp too much for the 6.5 amp motor?

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11010010110 (author)luch2009-02-24

the switch V / A are for the switch only. the other parts of the circuit dont feel them. if you use switch of very high rating it is ok the light switch should be ok if it does not flash too hard when switched on-off (arcing in the switch shortens its life)

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luch (author)110100101102009-02-24

Thanks so much for all your help. It's great to have a site like this, but without contributors, such as yourself, it would be worthless. Thanks again!

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NobodyInParticular (author)2009-02-24

Your switch should have ratings printed on the side. If not, try looking at the thickness of the metal and insulation in the wires. Compare that to wires whose rating you know.

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user

in a switch the speed at which it opens / closes affects the max current too switches with identical contact size will hold the same current when closed but the one with stronger spring will stand inrush currents better

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landmanhall (author)2009-02-24

Im certainly not an expert but I belive the amperage of the switch refers to the max amount of amps it will handle so 6.5 should be ok. Woodworking equipment as well as vacume cleaners use amperage like that.

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luch (author)landmanhall2009-02-24

Awesome! Thanks for the reinforcement!

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