Multiple Motion Sensors

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mkgrady

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Massachusetts
Is there any reason two motion sensors would not work? I have a floodlight to turn on and want to use two sensors so that if either sensor detects the flood light turns on.
 
mkgrady said:
Is there any reason two motion sensors would not work? I have a floodlight to turn on and want to use two sensors so that if either sensor detects the flood light turns on.
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It will work. We have had the discussion here in the past and some think it is not compliant because of "paralleling of conductors" that happens. I myself don't see this as a violation of those rules, we are not "paralleling conductors" to attain an overall higher ampacity out of the parallel set.
 
kwired said:
It will work. We have had the discussion here in the past and some think it is not compliant because of "paralleling of conductors" that happens. ...
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I'd like to see what wiring layout they are looking at to make that argument. I don't see it as any different than any other type of switching from multiple locations. I'm not referring to three- or four-way setups, either.

Say, for example, a count-down timer on each end of a room, and either timer switch turns the lights on. Both must be off for the lights to be off. Plenty of applications for set-ups like this, whether it's a motion sensor switch, photocell switch, or even if someone wants plain, dumb, parallel switches for whatever reason.
 
MAC702 said:
I'd like to see what wiring layout they are looking at to make that argument. I don't see it as any different than any other type of switching from multiple locations. I'm not referring to three- or four-way setups, either.

Say, for example, a count-down timer on each end of a room, and either timer switch turns the lights on. Both must be off for the lights to be off. Plenty of applications for set-ups like this, whether it's a motion sensor switch, photocell switch, or even if someone wants plain, dumb, parallel switches for whatever reason.
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To operate with any or all switching devices as the trigger, the switches must be parallel to one another.

There is a difference between parallel elements of a circuit vs putting items in parallel to one another to be able to handle higher current. Being able to handle a higher current is what 310(H) is all about IMO. Some think it means no paralleling at all unless conditions specified are met.
 
Knuckle Dragger said:
They were always on the same circuit though.
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That point brought back a memory of my helper days:

We were at an existing home to do some work, and I discovered an extra black wire on the load side of a switch by the front door that controlled an exterior flood light. The white wire was capped, so I deduced it could be from another source, and traced it to a security alarm system.

A small relay had been added that energized that black wire from the alarm's supply circuit when the alarm tripped. I decided to check and, sure enough, the alarm and lighting circuits were on opposing lines. Had the alarm ever tripped while the light was already on, ka-pow!

I immediately rewired it so the power to the line side of the relay was provided from the lighting circuit, by connecting the unused white wire to the hot in the switch box, as it should have been wired by the original electrician. (The alarm system was installed when the house was built.)
 
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