Calling All Electronics Geniuses !

[Dawner]

In my opinion, one should not switch the neutral lead, unless, it is on a simple two prong plug in; the neutral should run right through, as in a household light switch; in most installations, neutral is bonded to ground.

You always shut the hot down. ( its a safety thing ) You don't want to work on something with a live HOT wire floating somewhere around in it .. By the way it really F#!$ing stings if your lucky ... If your not lucky it will kill you. So do you feel lucky ?

 

[British Steel]

Here in the UK most supplies are through RCDs (residual current disconnectors) so a neutral to earth current (neutral can float a little way off earth depending on loads on the three phases) WILL trip the supply - makes it worth switching the neutral too!
I've seen a lot of Chinese tools (especially green ones...) with 'safety' interlock switches in the neutral so if the chuckguard / whatever microswitch fails (being rated for 1 amp max with a 1000w motor running through it) a dead lathe / mill still has 240v on the internals - a nice surprise

 

[Dawner]

Yeah double pole, double throw. Confirm with a meter to avoid electrical fire and DEATH but most likely with the switch flipped one direction 1 and 2 are connected to 1a and 2a, flip the switch the other way and 1 and 2 are connected to 1b and 2b.

Regarding that plastic housing, WARNING 1 million Ohms!!

yeah that sounds about right to me, common usage for this type of switch would be for like a " forward /reverse switch" providing the rocker switch has a center position if not it should be wired after a power on/off. You must switch main power OFF to the equipment, then wait till the machine comes to a full STOP, then select your new direction, finally switch your main power back ON. Internally the motor is happy going one direction, it doesn't care which direction as long as its the same direction . It would be the same as driving down the freeway at 60 mph and throwing your car in reverse, (not a good idea). but something going to give (if your lucky it will just stall). OH YEAH one more thing "1 million Ohms won't kill you,.. its the watts

 

[coolidge]

yeah that sounds about right to me, common usage for this type of switch would be for like a " forward /reverse switch" providing the rocker switch has a center position if not it should be wired after a power on/off. You must switch main power OFF to the equipment, then wait till the machine comes to a full STOP, then select your new direction, finally switch your main power back ON. Internally the motor is happy going one direction, it doesn't care which direction as long as its the same direction . It would be the same as driving down the freeway at 60 mph and throwing your car in reverse, (not a good idea). but something going to give (if your lucky it will just stall). OH YEAH one more thing "1 million Ohms won't kill you,.. its the watts

I saw that printed on a circuit board once, DANGER 1 million ohms, hilarious. lol

 

[hman]

yeah that sounds about right to me, common usage for this type of switch would be for like a " forward /reverse switch" providing the rocker switch has a center position if not it should be wired after a power on/off. You must switch main power OFF to the equipment, then wait till the machine comes to a full STOP, then select your new direction, finally switch your main power back ON. Internally the motor is happy going one direction, it doesn't care which direction as long as its the same direction . It would be the same as driving down the freeway at 60 mph and throwing your car in reverse, (not a good idea). but something going to give (if your lucky it will just stall). OH YEAH one more thing "1 million Ohms won't kill you,.. its the watts

There is a simple answer to this issue. It's an item I ran across on some long-forgotten equipment about a brazilian years ago, but never knew the nomenclature. I did very thorough search about 2 years ago, and more-or-less lucked into it. It's called a "hesitation switch." This looks like a normal DPDT toggle, but in order to get from forward to reverse (or vise versa), you have to move the toggle from the "A" side that it's on toward the center, then stop and let it move it slightly the other way to unlatch some kind of mechanical interlock, then move it the rest of the way toward the "B" side. Thus, "hesitation."

They're not especially cheap, but they CAN prevent accidental reversals! Eaton is the only manufacturer I know of.

http://www.eaton.com/Eaton/Products...Controls/Toggles/HeavyDutyHesitationSwitches/

http://www.amazon.com/Eaton-Switches-7992K10-HESITATION-ON-OFF-ON/dp/B00DDDEIS6

http://www.klocknermoeller.com/Eaton/Eaton pdf/11/11-6-7.pdf