15 vs. 20 Amp 3-Way Wall Switches

[gfretwell]

Most people (wives) don't want a bat handle switch in their hall.

[Bod F]

If you have two-phase power, you can also use a 3-way switch as a phase switch.

Connect L1 to one of the traveler screws.

Connect L2 to the remaining traveler screw.

Connect the load's black wire to the third screw.

Connect the load's white wire to neutral.

Now just toggle the switch to switch the load between the two phases.

[Ralph Mowery]

The attic fan where I used to live had a switch for 'on, off, timer'. You turned it on all the time , cut it off, or there was a timer next to the switch. It was on a flat plate about the size of most light switches, but the switch was large and almost flat. You pushed it in toward the wall for off or timer and it stayed in the middle for off.

[Clare Snyder]

need anything more - the timer is on (timed) or off. The bypass is on or off. If the bypass is on it doesn't matter what the timer is set to

- it is ON. With timer off and bypass off, it is OFF. both fit in a tandem box

[micky]

In addition to the thermostatic switch, my roof fan has two switches in one box, mounted sideways.

One switch turns it On when it would be off. This was recommended for use after a hot shower which fills the attic with humidity, but I don't take hot showers.

One switch turns on Off when it would be on. I use this in late fall and early spring to let the sun heat the house and save on fuel to heat it. Or when it's so hot out that the fan would run all night (but then I usually forget to turn it on the next morning.)

Normally the first switch if off and the second On. With a line on each one whose parts are in-ine when they are set normally.

But what I should have put in is a timer, because sometimes it is so hot out at night that the attic never cools off enough to stop the fan, and it runs from about 11 in the morning to at least 9PM the following day. There is no point to the fan's running if it's as hot outside as it is in the attic. It only happens a few days a year but it annoys me. So I may put in a timer wall switch. I think it will have to be one that doesn't need a neutral, because I don't think I ran a neutral (from the fan to these two switches). It would have been easier if I'd done it in the first place. So maybe I won't do it.

[micky]

If it wasn't recorded, how did the conservatives mannage to find a version attributed to the various people they attributed it to. Face it, they made up the quote.

The otherwise almost unknown Scot who said something similar, who was cited in another post, was pessimistic about democracy in general. He thought all democracies were doomed and this was just one stage each would go through. Maybe he's right, maybe he's wrong. He has no history of being a great man.

But more importantly, almost no one has heard of him. To attribute something to him wouldn't give it the status that they hope to get who attribute it to someone famous who did NOT say it. That's the purpose of a forgery.

[Wade Gattett]

OP here- Umm, interesting bunch of posts.

I didn't see any answers, though, to my original questions about using a

15A switch on a 20A circuit and might that usage have contributed to the switch's failure...

[trader_4]

Missed this? I made the first response.

'I believe the answer is that the switch is sized to the load, not the breaker. So 15A is OK. It's hard to imagine a fault condition where a 15A switch is going to create a safety hazard in that application. As to whether a 15A switch contributed to your switch failure, I'd say yes and no, mostly no. Your small fan load is nowhere near the limit of either a 15A or 20A switch. But a 20A switch may be built a bit heftier, might take more openings and closing, etc than a 15A one, so a 20A one might have lasted longer. There are also differences among 15A switches, ie a cheap chinese one or a better spec grade one, (probably from China too :) "

[trader_4]

Why does taking a shower fill the attic with humidity? Bathroom fan venting into the attic instead of outside? Something is very wrong there.

The attic fan switch is set too low. And adequate natural ventilation, eg ridge vent with soffit venting is better. I'll bet you could turn it off from about 8PM until the next morning and not see any difference with the temperature inside. And if you do, something else is wrong, eg inadequate insulation.

[Mark Lloyd]

[snip]

Why consider "unstable" to mean not there? An OFF position is a necessary consequence of the switch breaking one connection before establishing the other connection.

[trader_4]

This is what you described:

"A double-throw switch does have center off, although it can be difficult to get the switch into that position (a spring tries to pull it away from the center). I have had this happen accidentally, one switch in this (center) position means the light can't be turned on at the other location. "

That is unstable, it's not what the switch was designed to do, it's not reliable. Suppose it's a switch for a mixer or similar, you put the switch in the middle position, assuming that's off, and go to work on it? A switch with a center off position has a detent so it goes into the off position and stays there, it doesn't have a spring trying to pull it from an unstable position to one of it's stable positions.

[Clare Snyder]

Simple answer. Switch is sized for the LOAD. If the fan draws less than the rating of the switch it is not a problem. For example, a standard Leviton 15 amp toggle switch is motor rated for 1/2 HP on 120 volts AC and 2HP on 240 volts AC, and 15 amps (1800 watts) of incandescent lighting load.

On a 15 amp circuit one 1800 watt load would max out the circuit - or

3 600 watt loads. A 20 amp circuit would allow 4 600 watt lighting loads. I chose 600 watts rather arbitrarily as most lighting dimmer switches are rated at 600watts incandescent. SO - unless the fan is more than 1/2 HP a 15 amp switchis just fine - assuming it was a "motor rated" switch - which MOST are. A 20 amp switch is motor rated for 3/4 HP on 120 volts.

[Clare Snyder]

On a "snap action" switch remaining in the off position would constitute a switch failure.

[Ralph Mowery]

Seems that was the way it was done at one time. I bought a house that was built about 1965. The vent in the bath was just to the attic. Also very little insulation which was that shreaded paper type. What was it called, something like blown celulease. There were about a dozen houses in the neighborhood on a similar floor plan.

[gfretwell]

It was pretty common to vent fart fans into the attic until the mechanical codes caught up with the problem.

[Wade Gattett]

Ah, thanks.

The switches only control the 85 watt ceiling fan.

But also on that circuit, there's two floor lamps (LED bulbs now) and the entertainment corner: two year old big honkin' 7.1 home theater receiver with 5 speakers plus a 12" powered subwoofer, 10 year old plasma TV, cable box.

So I'm thinking the switch failure nothing to do with it being rated 15A....

[Clare Snyder]

Absolutely

[micky]

In my case, the tube from the bathroom fan ends right below the ridge vent.

FTR I didn't say the attic was filled with humidity. I said it was recommended for that reason. I don't take hot showers and I don't go to the attic afterwards to see if it's humid there. I put the switch in so the next owner of the house would have it.

Pink fiberglass.

[Clare Snyder]

Blown cellulose was the common insulation back in the sixties. Shredded newspaper with borax? (Borate) flame retardent. It is still actually pretty widely used in some places.

[Wade Gattett]

Not really sure what you're asking...