Single or double pole mains switch in USA?

In an instrument which will be sold in the USA, is there a requirement for double pole switching of the mains?

There'll be a chassis-mount IEC mains input plug at the rear and a mains switch on the front, then off to PSUs and low voltage electronics.

It may seem a silly question, but the mains switch used on the prototype is rather nice but only available as single-pole.

Is there some guidance which is less than hundreds of pages of regulation?

Cheers

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Syd
Reply to
Syd Rumpo
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You will probably need to comply with ISO/BS/EN/UL 61010-1:2010 which states:

6.11.4.2 Switches and circuit-breakers An equipment switch or circuit-breaker employed as a disconnecting device shall meet the relevant requirements of IEC 60947-1 and IEC 60947-3 and be suitable for the application.

I can't see anything which requires double-pole switching. I don't have copies of 60947-1 and -3 to check those however.

John

Reply to
jrwalliker

All those IEC specs are expensive, and every one refers to a few more.

Nice racket.

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John Larkin         Highland Technology, Inc 

lunatic fringe electronics
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Reply to
John Larkin

The 'General' specs refer to 'particulars', I think.

Cheers

Reply to
Martin Riddle

Opps, its the other way around ;)

Cheers

Reply to
Martin Riddle

I believe its only medical products that require double pole and 2 phase equipment.

Cheers

Reply to
Martin Riddle

2 phase? Please educate me on this. I know that single phase and 3 phase are common, but I have never encountered 2 phase.
Reply to
John S

Not for 120V appliances, It's not even allowed, AFAIK.

Reply to
krw

Probably ungrounded (or balanced).

Reply to
krw

Not so sure about that. Pretty sure you MUST switch (and probably fuse) the hot side. That means a polarized plug and observing polarity.

I've seen equipment that has a polarized plug and also switches both, thoug h have no idea why they did it. Also I think if you use a non-polarized plu g you have to switch both.

Which brings up a mystery. Working on a DVD/karaoke player. Has a polarize d plug but uses the type of connector you used to see on alot of Technics s tereo equipment. On the back of the unit it will go in both ways. That real ly makes no sense especially since those units only switch one side of the line.

I'm pretty sure what is not allowed is to switch the neutral only.

Reply to
jurb6006

Pretty sure what people mean when they say that they mean something that runs off 240 volts and therefore, in the US, has two hots. Electricians and the power companies don't call it that but some people do.

They also used to have four phase but I don't see any real advantage to it. Maybe they didn't either because it is apparently long been phased out. (the pun fits...)

Reply to
jurb6006

Yes, but it is unlikely to matter to your application.

Items that use two HOT wires and ground (developing 240VAC from a pair of

120VAC HOT wires) must be served from a two-pole circuit breaker in the wiring of buildings. This typically applies to electric stoves/ovens and water heaters.

If there is a local safety cutoff switch (for servicing of such items) it too must disconnect both HOT wires. Your box is described as having a removable power cord, so it doesn't need a safety cutoff of this sort.

Reply to
whit3rd

really?

two leads 90 degree shift..

Now maybe a split phase would be closer since it uses a single secondary with a center tap to get 2 legs 180 degree referenced from the ct.

Really... But then again, I bet you can't be educated anymore than Slowman.

Jamie

Reply to
M Philbrook

There is no need to switch anything (as looking at any consumer electronics will tell you). Polarized plugs aren't required if the unit is double-insulated. I'm not sure about a switch in the double-insulated case though.

That's not safe. A fault in the switch leaves the guts hot but there is no indication of such.

Does it have UL stickers?

Which can happen in your device, above. Dumb.

Reply to
krw

Thanks all for your comments, looks like a single pole is fine if the inlet is polarised so that I can be sure (FSVO 'sure') it's switching the live.

Cheers

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Syd
Reply to
Syd Rumpo

So then a transformer with a center-tapped secondary running on a single-phase supply is a device which converts single-phase to two-phase? You are dumber than a fence post and are much less useful.

Reply to
John S

How often have you encountered a mains supply with 90 degree phase shift, smart ass?

Reply to
John S

Equipment like AT-class PCs had an IEC input and two pole mains switch (either integrated into the powersupply or on a flying lead)

dunno why they did that.

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Reply to
Jasen Betts

Finally someone has mentioned Scott transformation. Beat me to it!

Reply to
pedro

But, according to Philbrick, two phase voltages are only 90 degrees apart. Three phases are 120 degrees apart. Please reconcile that discrepancy.

Reply to
John S

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