what happens when 2 separate "hot" lines from same breaker get tied together

[John Nic]

I'm trying to wire some lights so that when either of 2 different situations
arise these particular lights operate. I have two separate switches on the
same breaker that go to their own device (one a soffit plug and the other a
motion light). What I want to do is when the soffit plug is hot I want
these new lights on and when the motion light is on I want these new lights
to be on, and of couse if both situations happen at the same time I want the
new set of lights to be on. I'm confident I have the wiring firgued out
barring this one possible glitch. When both "line" wires come into the
junction box and feed the one load wire what's going to happen?

Thanks,
John

PS I can't change any wires, they are all supplied with 14/2

 

[John Nic]

thanks,

what exactly would this relay be called if you could tell me.

John

| I'm trying to wire some lights so that when either of 2 different situations
| arise these particular lights operate. I have two separate switches on the
| same breaker that go to their own device (one a soffit plug and the other a
| motion light). What I want to do is when the soffit plug is hot I want
| these new lights on and when the motion light is on I want these new lights
| to be on, and of couse if both situations happen at the same time I want the
| new set of lights to be on. I'm confident I have the wiring firgued out
| barring this one possible glitch. When both "line" wires come into the
| junction box and feed the one load wire what's going to happen?

The "glitch" you'll end up with is when either switch is turned on, then
everything (soffit plug, motion light, and new lights) comes on. This
is because when you join the two line wires in the junction box, you are
effectively connecting it all together.

Had these been on opposite phases in a 2 pole center tapped feed, then
you would have (hopefully no more than) 2 tripped breakers.

If you want a common light to indicate if any of other loads is on, then
what you need to do is isolate them by having each switched circuit power
a relay that has parallel contacts powering the new lights.

http://ka9wgn.ham.org/ |

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[SQLit]

I'm trying to wire some lights so that when either of 2 different situations
arise these particular lights operate. I have two separate switches on the
same breaker that go to their own device (one a soffit plug and the other a
motion light). What I want to do is when the soffit plug is hot I want
these new lights on and when the motion light is on I want these new lights
to be on, and of couse if both situations happen at the same time I want the
new set of lights to be on. I'm confident I have the wiring firgued out
barring this one possible glitch. When both "line" wires come into the
junction box and feed the one load wire what's going to happen?

Thanks,
John

PS I can't change any wires, they are all supplied with 14/2

What you need is a relay to separate/switch the circuits. This is real
common in theaters and stage situations. For a show they want to shut down
the exit signs, if there is an emergency they want the lights to come on
immediately.

A standard ice cube would work depending on the load. Square D makes a CO3
relay that is I think 20 amp and comes with an NO and NC contact on it. Down
side to this is that the coil is pulled in all the time. Eventually it will
fail and you will only have one switch working.
A latching relay would be better but then if there is no power you would not
be able to switch from one source to the other. Go with the ice cube
relay. 5 or 10 years from now you may have to replace it.

http://relays.omron.com/my/Relays-MY_Ad.htm