Switching Circuit

Oct 10, 2009 40 Replies

Switching Circuit



A buried wire between house and garage has only 3 conductors. How do you utilize them to provide both constant power from house to garage, and 3-way switching for lights in the garage at either house or garage?



I used two 3-way switches and a relay.



formatting link



Jon


I already replied to this on alt.electronics, where you didn't crosspost, and I'm crossposting it to sci.electronics.basics for good measure. You don't need a relay: (View in Courier) HOT NEUT | | +---O-->\ /

Is this acceptable by electrical code? Depending on switch positions, the lamp's white wire may be connected to neutral or hot, and in one set of switch settings, both white and black are connected to hot and the lamp is "off".

Would seem to be against code because a copper conductor is normally now required from building (house) entry ground point to all recepticles.

John G.

You can do it simply: one SPDT relay and one 3-way switch in the garage, and a regular switch in the house.

House Garage ------------------- ------------------------------------ | | | | | House | | | | Switch | | | | o----------------rly1---------------------+ | | +---o | | | | | | | | o-------o | | | hot----+-------------------+---o o---lite---+ | | | | | o-------o | | | neut---+ | | | Garage | | | | | | [Recpt] Switch | | | | | | | | | | +-------------------+----------------------------+ | | | | | ------------------- ------------------------------------

Switching the neutral is a NEC violation - the arrangement above avoids doing that.

Ed

finally, some one that knows something!

I take my hat off to you sir! :)

On a sunny day (Sun, 11 Oct 2009 21:39:49 -0400) it happened Jamie wrote in :

Yea, but it swallows relay current if house swich left on 100% of the time.

What we need a a PIC solution :-) LOL

ou

ay

If you only want to draw power when the light is on:

. ----------------------------------------------------+----Outlet ! D1 . D3 ! ! O----!

Yes, it's tragic, a real strain on the budget. The relay coil (e.g Omron G2R) draws 7.5 mA at 120 VAC when the house switch is on. At say 10 cents per kwh, it would cost you 78.84 _cents_ per _year_ if you left the house switch on 24/7.

Ed

Yes, you could also use magnetic toggle or rotary relays with a momentary switch at any point on the line. We do that here for our garage using a rotary relay. We have 3 operating points in the garage and one in the house using 3 wire/w grd in a sealed PVC pipe under ground. We also have a #6 4 conductor cable running out there. That cable runs outlets and some heavy equipment.

you=20

3-way=20

John F you should have looked at his link.

What makes you think I didn't?

you=20

3-way=20

Because he included your circuit and gave you credit for it in that page. I would thus have expected a different response that reposting your circuit.

Skal

If I hadn't followed his link, how would I have been able to determine what his wiring looked like and suggest a way to get rid of the relay? The sequence of events was: 1. He posted his link. 2. I followed it, modified the circuit, and posted the mods and some info about crossposting. 3. Ed posted a fix for my neutral-switching error. 4. The OP read my post, and Ed's, and posted them to his site, showing them as mods to his circuit. Any other way would be the cart leading the horse, no? JF

"JosephKK"

do you=20

and 3-way=20

good

It seems that i might have missed an update to OP's site, or did the change occur before i saw it the first time?

3-way
Dunno...

3-way

Well, some comment here. Yes, by today's code it is an error. But it's not like the typical (at least for me) error where I put the &$*%+*! resistor in the wrong place on the schematic or leave the damn thing off altogether, etc. It's a NEC code error because they changed the rules after the game was started. Electrician friends tell me it used to be allowed by code years ago. They call it "Chicago wiring" and say they still run into it on occasion today. I don't know when the rules changed.

Ed

"JosephKK"

"JosephKK"

How do you=20

and 3-way=20

good

=46air enough.

So how many wires must you have to comply with NEC?

Surely NEC does not allow the use of relays for this!

Can't switch hot side to bulb threads in a light bulb cleat.

And if outlets and light circuits can not share a hot line or neutral then can they share the ground wire?

I count 5 wires and a ground.

HELL of a cable to run to a GARAGE!

That's a lot of copper!

3 wires #14 2 wires #12

minimum?

Even an X10 module would violate NEC if the lights are on the same hot as the outlets, only eliminates one #14 wire.

Running that one more wire would be cheaper and X10 modules are a maintenance liability.

Garage door opener would push #12's to #10 wire, right?

Fluorescent Lights are nice in garages but they're a nightmare if you get freezing weather.

So what are people going to use in Garages when incandescents are outlawed in favor of flourescent ""light bulbs""?

Among the new fluorescent ""light bulbs"" I found a flourescent flood light.

Totally worthless in Northern US states in the winter time.

Not a mere convenience because severe weather is NOT a time to have such a failure.

There's no mention of this problem on the product.

How will the Californa mentality green weenies resolve this little problem for over 25% of the USA?

BTW, one solution for flourescents that won't light in the cold is to LEAVE THEM ON! HORRORS!

Tell me there's some magic to these new fluorescents to overcome this [ not too small ] problem!

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