Is this a legal use of a 3 way switch

[Jim W in Tampa]

Thanks, lot of good advice.
My load on the still working load just went drastically down because all the 240 loads just died. They were 2 x 3 1/2 ton units, another 5 ton unit, 2 ton unit, water heater 4500,water pump 2 hp, hot tub, So load went way down instantly.
What could have stayed up were all the lights and 120 receptacles and 6 x 1/2 ton wall units on 120 and 3 x 1 ton wall units on 120. So likely less than 100 amps.

The idea of center off i like because this system would be used if on backup gen for long outages in huricane to balance loads

A tie handle would be required per nec but only cause of chance of unskilled electrician ever touching it and that day will come as i am 62

Will not assume both legs are dead and we do know when power is restored both are live once again

Am thinking this out carefully before and if i follow thru.
Would run switches from my office in EMT from 2 main sub panels. Run would be 20 feet and because of derating #10 would only be switching maybe 6 important areas.
Might prove to be more trouble than its worth.
Sound system stayed up as it is on UPS with 2 marine battery. Some of the 120 wall units could been simply pluged in on another plug on live side.
Will be creating a drawing for all my electric because it would drive even a good electrician crazy figuring what i have.

I think there is a web site out there to help do load calcs, does anyone have link.
I started to do as Bob suggested and it will be hard with my unusual loads and could be over 200 amps if i don't shed the unused loads.

 

[Split Bolt]

One word of caution: Around here, there are a LOT of old houses that have knob & tube wiring and VERY old cloth 2-wire romex that had no grounds. These houses all have "Tennessee 3-ways" or "Lazy Susan 3-ways," whichever name you prefer. Basically, a hot & neutral were connected to the traveler terminals and the common goes to the light. This way, the light will go on and off because it will either have a hot/neutral, hot/hot, neutral/neutral or neutral/hot going to it, depending on the switch positions. VERY dangerous and confusing to troubleshoot! Anyway, I digress: I have seen cases where certain 3-way switches don't disconnect one traveler before connecting the other all the time, especially when flicked quickly! If you flip it slowly, everything works OK, flip it too fast and the fuse blows!

 

[jap]

as far as the voltage rating,

Why would the switch have to be rated at 240v ? you wouldnt be switching 240 simaltaneous.

if you put 2 seperate circuits on a 20a 125v Duplex receptacle you have 240v available, although the recept is not indicated 240v.

Whats the difference?

I would be more concerned about shorting across the switch.

 

[Jim W in Tampa]

as far as the voltage rating,

Why would the switch have to be rated at 240v ? you wouldnt be switching 240 simaltaneous.

if you put 2 seperate circuits on a 20a 125v Duplex receptacle you have 240v available, although the recept is not indicated 240v.

Whats the difference?

I would be more concerned about shorting across the switch.

It is the concern about the flashover being its 240 volts across switch that is being debated.
If i do it i will be wanting center off switches. Not sure if its worth the cost. Labor is not issue
Anyone have idea as far as cost for a switch like this, single pole

 

[TOOL_5150]

I used a 3 way switch in my house from 1 20A breaker to the common terminal of a 3way, then out of the 3 way to my dual speed whole house fan. Is this actually a violation?

~Matt

 

[Jim W in Tampa]

I used a 3 way switch in my house from 1 20A breaker to the common terminal of a 3way, then out of the 3 way to my dual speed whole house fan. Is this actually a violation?

~Matt

Don't think so and actually pretty clever. I might try that on one of my AC package units to control blower speed . Thanks.

 

[Volta]

I used a 3 way switch in my house from 1 20A breaker to the common terminal of a 3way, then out of the 3 way to my dual speed whole house fan. Is this actually a violation?

~Matt

I don't really know, but I don't think it is. You have only one source. I think the UL/lack of testing trouble is with using it as an Manual Transfer Switch, with dual sources.