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paulz
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# Posted: 17 Sep 2024 11:28pm
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Here’s a weird one. This little on off switch failed. I had a spare so did what any curious time waster would do, opened it up. I did sand the corroded points and got it working again, but look at the third (ground) terminal, it goes to nothing! Is it just supposed to arc across if there’s a short? Or is it just a cheap a** switch?
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gcrank1
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# Posted: 18 Sep 2024 12:14am
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Maybe the pin just 'polarizes' the C-A switch?
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ICC
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# Posted: 18 Sep 2024 12:17am - Edited by: ICC
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Is that the sort of thing that gets plugged into a receptacle, then something like a lamp can get plugged into it and the switch turns that thing on-off? The device to be turned on-off would be plugged into the unseen face of the left-hand part.
If so, that would be normal and correct. The ground connector simply passes through the switch item. Same with the neutral connector. Only the hot side connector passes through the switch and would be turned on & off; connected and disconnected. Ground and neutral stay connected as a simple pass through connection.
Are the flat connectors of different width, neutral being wider?
Neutral = the White wire = the Wider connector pin
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paulz
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# Posted: 18 Sep 2024 12:25am
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Yes it is Izzy, and you’re absolutely right, you caused me to think it through. Just caught me by surprise at first. 
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ICC
Member
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# Posted: 18 Sep 2024 12:39am
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Brain exercise is good
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paulz
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# Posted: 18 Sep 2024 11:38am
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I have lots of DC experience from years of vehicle mucking around but AC has never been a strong suit, and you’re right, my brain needs all the workout it can take these days.
Another thing that confused me was that both hot and neutral sides run to the switch, see photo. Wasn’t until last night I finally figured out why.
And, the ground lug has a metal tab that sticks up next to it, like it ought to go to something.
Lots to understand for that little 2$ switch. 
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ICC
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# Posted: 18 Sep 2024 12:49pm
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Quoting: paulz both hot and neutral sides run to the switch, see photo
That would indicate the switch is a DPST type.... Double Pole Single Throw.... It switches both the hot and neutral wires or poles (DP). and only has one function, either on or off (ST).
https://m.littelfuse.com/technical-resources/technical-centers/commercial-vehicle-tec hnical-center/poles-and-throws.aspx
The grnd terminal thing could simply be an off the shelf part and the was not needed ??? Or any other guess
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paulz
Member
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# Posted: 18 Sep 2024 01:35pm - Edited by: paulz
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Quoting: ICC That would indicate the switch is a DPST type.... Double Pole Single Throw.... It switches both the hot and neutral wires or poles (DP). and only has one function, either on or off (ST).
Ok. One side passes direct through, the other goes through the switch. I figured it was to light the switch when in the on position.
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ICC
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# Posted: 18 Sep 2024 02:47pm
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Quoting: paulz light the switch when in the on position
Bingo! Yes, I never thought of that.
Then there are switches that have a light that is on only when the switch is off. Makes it easier to find in the dark and goes out when the switch is turned on. I forget where I ran into those.
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travellerw
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# Posted: 18 Sep 2024 03:06pm
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ICC nailed it..
However, its a good opportunity to talk about Class 1 and Class 2 (double insulated) devices.
Class 2 items do not require the ground pin to be connected. These items are considered double insulated and would require 2 insulation faults to become dangerous to the user.
So not everything without a ground is dangerous or crap. Of course there is still a lot of dangerous cheap crap coming from a particular county. Sigh LED lights, so many LED lights with metal housings not grounded.
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paulz
Member
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# Posted: 18 Sep 2024 05:36pm
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Quoting: ICC Then there are switches that have a light that is on only when the switch is off. Makes it easier to find in the dark and goes out when the switch is turned on. I forget where I ran into those
That would be nice, unless you are used to the ligh meaning it’s on.
I have mostly all old tools, all minus the ground pin. This Makita sander doesn’t even have wide and narrow prongs. All double insulated?
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ICC
Member
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# Posted: 18 Sep 2024 06:52pm - Edited by: ICC
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Quoting: paulz I have mostly all old tools, all minus the ground pin
I am not sure when the double insulated standard was introduced. If your tools with two prong OEM plugs are old enough they could predate the standard and be quite ready to zap someone. I have a truly old Porter Cable drill that was my grandad's. I do not use it; it is just a keepsake. I do remember when it would sometimes send a tingle thru the all metal case.
An double insulated tool has a plastic, polycarbonate or other non conductive casing. On the tool label it should have a "double box" symbol OR the words "double insulated". It will not have a three prong plug.
I believe a double insulated device is supposed to have a two prong polarized plug (one wider prong). BUT I am not certain about that. Some 2 pin polarized plugs have the neutral prong only wider at the tip.
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travellerw
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# Posted: 18 Sep 2024 11:16pm
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A rule of thumb is if anything you can touch is plastic, then its most likely double insulated (think new shop vacs).
However, I have seen things like sanders that had a metal platen and no ground pin. I'm guessing there is some standard for insulating that exposed metal from all the electrical bits so it is double insulated.
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paulz
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# Posted: 19 Sep 2024 03:22pm
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Thanks Trav. The tools I pictured are all plastic but I’m sure there’s some metal bodied tools around. Never paid much attention but will now. Amazing I’ve made it this long. Been shocked many times, never seriously. Course I was younger and healthier then, even barefoot sometimes! Time to more attention!
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