[lou-ace]

hey ya all. good to be back, bow hunting is overrated, unless of course your freezer is as full of Elk meat as mine is. I've got my components comming curtis 1231c controller, albright contactor, fuses, amp meter.... bla,bla,bla, and it occured to me as I'm designing my schematics, why not place all my switches on the negative side vs. the power side of my design. as long as I'm interupting the circuit the switches would be just as effective yet subject to much lower stressors....... any obvious problems with that?

 

[sjc]

hey ya all. good to be back, bow hunting is overrated, unless of course your freezer is as full of Elk meat as mine is. I've got my components comming curtis 1231c controller, albright contactor, fuses, amp meter.... bla,bla,bla, and it occured to me as I'm designing my schematics, why not place all my switches on the negative side vs. the power side of my design. as long as I'm interupting the circuit the switches would be just as effective yet subject to much lower stressors....... any obvious problems with that?

Most of my electrical experience is in building electronics. One generally doesn't switch the negative because it keeps the device hot, and so an accidental path to ground while working on the device leads to a shock.

 

[peggus]

Exactly the same amount of stress, positive or negative doesn't matter.

 

[piotrsko]

yes to both above, HOWEVER back in the dinosaur days of electronics, we placed switches on the negative side because they tended not to arc as bad and you could often get by with the switch you had on hand. I would think that a beefy but very crude disconnect on the hot side and a smaller often used switch on the neg side might be a wee bit more elegant. Look at the points on a 60's style distributor as illustration.

 

[sjc]

yes to both above, HOWEVER back in the dinosaur days of electronics, we placed switches on the negative side ...

Oh, I own a house built in 1915 (ancient days, in the USA; knob and tube wiring). It's delightful (not) how they switched and shared neutrals in those days. Nothing like disconnecting a circuit at the panel only to find out it's still carrying current because someone in days gone by tied it together with another...

My favorite story is now I was standing in the basement working on a junction box just in front of the panel. Two different circuits entered the box, and I had the breakers off for both of them, even though I was only working on one. I was fiddling with the circuit of interest for a few minutes, when I noticed something odd. From where I was standing, I could see out the basement window up to the outside garage lights. Every time I closed the circuit in the box, the garage lights went out. When I broke the circuit, they came on. Yikes!

An electrician friend spent an afternoon coming to the obvious conclusion: somewhere between the house and the garage the two circuits had been tied together. We solved the problem by tearing off the back porch for a kitchen expansion, removing the wiring for the outside garage lights