Does anyone need a high voltage switch

[Lloyd]

>:(hehehehe

lloyd

this could happen to some unsuspecting person http://www.wimp.com/switchopening/  then what would yor advice be??

Tell me how that could happen without a 500kv power supply?  

You need to read your own signature, Lloyd.

The Devil is in the details, ignore the details, and you create the Devil's playground.

[Lloyd]

Well, in that case we should all remove the circuit breakers from our homes to be safe.  

Are you *actually* an electrician, Lloyd? I know you work on boat electronics but that requires no liscense.....

As for me, I own a factory that makes and sells electrical products, mostly various types of cord sets. What do you think I do at the "shop" I'm always talking about? Yes, I invented those products, and got them UL approved too. You can find them in a Northern Tool catalog, among other places.

I'm regulated by the US Coast Guard... and am liable for anything I do. In Federal Court.

[mobile_bob]

ok fella's let play nice!

a better option might be a magnetic starter or contactor

a size 5 three phase contactor will handle the amount of power referred to here
and could be safely controlled with a cheap light switch

they can be found on ebay, yes they can be expensive but if you are lucky they can be found
very reasonably priced at times, most are rebuildable/repairable too.

bob g

[JohnF]

OK boys;

This one has degenerated a bit so I have locked the topic.  As Bob says, try and play nice.

[mobile_bob]

actually a size 4 would probably be more than enough to do the job

as for using a breaker for switching
i think both you guys have it partly right

a breaker will likely work ok for a switch for a hot water tank for a very long time
because the heating element are largely resistive so there would be less arcing of the contacts

the same breaker switching an inductive load might have dramatically less life because of the inductive
kick upon break, making for a hotter break than what would happen with a largely resistive load.

the contactor gets around this by virtue of the dual set of contacts on each pole, two series connected contacts
per pole makes for a cleaner and cooler break of an inductive load.

the contact pads are also quite large a size 5 has contact pads that are about the size of a dime, usually made of a silver
alloy and specially ground to a shape that makes them more or less able to self clean with each actuation. all of which are
generally lacking in a breaker.

having said all that, i too have used breakers to switch things that might be better switched by other methods, however
because the load should be removed from an st head before shutdown perhaps the loads can be removed before the main breaker
is opened anyway, this would eliminate all chance of undue arcing that would perhaps shorten the breakers life.

something to consider also is a contactor has a control coil, generally of a lower voltage and consuming only a small fraction of the switched power
this enables control of the switching to be done via all sorts of other control circuits/switches, things like low oil pressure, high water temp, over/under speed to name a few.  because of these options i personally would suggest the use of a contactor of suitable size to do the main switching.

btw, i have in the past bought size 5 three phase contactors for less than a hundred bucks used, and contrary to popular thinking the contacts can be
reconditioned "if" one is very careful and uses and small point file followed by fine wet or dry paper to polish out the surface of the contacts keeping close attention to the original shape.

one can also use what is known as a reversing contactor, which is basically two contactors mounted on a chassis, with a mechanical interconnect
which forms an interlock so that only  one contactor can function at a time. this type of reversing contactor can be used to switch between generator and mains to the house load panel.

for what its worth, all contactors should be mounted in a sealed box, to preclude dust, bugs and other things that seem to find their way into the contacts and foul them.  the box also provides fire protection and containment for obvious safety concerns.

also contactors are UL listed as well as CE and other authorities for switching all types of AC loads, so if there were ever a fire the insurance inspector won't be able to fault the use of the product for that which it was designed to do.

ymmv

bob g

ps. i buy my contactors off of ebay, usually used allen bradly, however i also have bought other brands too, favoring ones that have contact kits available from wwgrainger in case i ever need service parts.  sized properly it is doubtful one would ever need a set of new contacts in the life of the genset in my opinion.