4 way motion sensor (outdoor)

kwired

Electron manager
Location
NE Nebraska
In my opinion putting the switches in parallel for that application is a violation of the NEC parallel conductor rules.

This has been beat to death in the past with no real consensus as to whether or not it is a violation or not.

I am not going to post any details as to why it is or isn't a violation, or it will just derail the thread, as it has at least two or three times in the past.

If it is a violation then one must run the sensors as a part of a control circuit and control a contactor with them, and then slave the lights off the contactor, as it is clear you can parallel switches of a control circuit.
 

Volta

Senior Member
Location
Columbus, Ohio
If lights are staying on all night, it is likely that motion is being detected or at least one motion sensor is defective, not a photocell issue.
I also don't find it very uncommon for detectors to 'forget' what to do, and need to be either power cycled or simply go through a dusk to dawn period.
 

kwired

Electron manager
Location
NE Nebraska
I also don't find it very uncommon for detectors to 'forget' what to do, and need to be either power cycled or simply go through a dusk to dawn period.
Lets just say when it comes to outdoor motion detectors that are targeted at the residential market, there is a lot of cheap crap out there and I myself am not much of a fan of any of them. I usually make customer pick out their own unit and I will install it for them with no guarantee as to how it will perform. If they want something that I will stand behind they will usually balk at the price.

I would rather tell them to put lights on a dimmer and let them run all night for security purposes, and you can turn the dimmer up when you have activity going on where you need additional light. That is exactly what I have on my home, photocell turns them on at dusk, dimmers are set to a low level and usually stay there unless we want more light for some reason.
 

iwire

Moderator
Staff member
Location
Massachusetts
This has been beat to death in the past with no real consensus as to whether or not it is a violation or not.
That may be your take on it but I think the words in the code are pretty clear on it.



I am not going to post any details as to why it is or isn't a violation, or it will just derail the thread, as it has at least two or three times in the past.
The OP should know that what is being recommended is a potential code violation.

If it is a violation then one must run the sensors as a part of a control circuit and control a contactor with them, and then slave the lights off the contactor, as it is clear you can parallel switches of a control circuit.
I agree, and if you find that clear you must also find doing it to supply lighting outlets is a violation.
 

iwire

Moderator
Staff member
Location
Massachusetts
I would rather tell them to put lights on a dimmer and let them run all night for security purposes, and you can turn the dimmer up when you have activity going on where you need additional light. That is exactly what I have on my home, photocell turns them on at dusk, dimmers are set to a low level and usually stay there unless we want more light for some reason.
I have a dimmer on some of my outdoor lighting, I have not added a PC yet.
 

kwired

Electron manager
Location
NE Nebraska
That may be your take on it but I think the words in the code are pretty clear on it.





The OP should know that what is being recommended is a potential code violation.



I agree, and if you find that clear you must also find doing it to supply lighting outlets is a violation.
Fair enough, but I will refer OP to some of the past discussion on this, as there is no winning the debate on either side.



http://forums.mikeholt.com/showthread.php?t=149532&highlight=ring+circuit

http://forums.mikeholt.com/showthread.php?t=138335 (nearly 200 posts in this one that got us nowhere)

Seems like there was another thread or two but am having trouble finding them, I either get too many results or none at all with my searches.
 

Lectricbota

Senior Member
This has been beat to death in the past with no real consensus as to whether or not it is a violation or not.

I am not going to post any details as to why it is or isn't a violation, or it will just derail the thread, as it has at least two or three times in the past.

If it is a violation then one must run the sensors as a part of a control circuit and control a contactor with them, and then slave the lights off the contactor, as it is clear you can parallel switches of a control circuit.

That would be an understatement.
 

readydave8

re member
Location
Clarkesville, Georgia
Occupation
electrician
If lights are staying on all night, it is likely that motion is being detected or at least one motion sensor is defective, not a photocell issue.
Problem I was concerned with was master photocel putting motion detector in to override, motion dectectors are not all the same, turning power off and then back on can sometimes make them stay on (Although it's supposed to be a much shorter "off" than would be if photocel off all day)

But the main drawback to plan: motion dectectors have been known to behave erratically, harder to troubleshoot with multiple motion dectectors, customers have been known to become unreasonable when a fairly new, perhaps a little bit expensive, system gives trouble while still relatively new.

And I have had jobs involving motion detectors that went fine, just not as often trouble free as jobs that don't involve motion detectors.
 

kingpb

Senior Member
As I like to think iwire is usually on target :sleep:and typically I am in agreement with his points :thumbsup: of view; I have to take opposites sides here.:cry:

If referring to parallel in the pure form of circuit theory, the sensors are individual paths or branches for electrons to flow, thus they do form a parallel circuit. But how does that apply to conductors in parallel :?

So, it is my opinion, and we all know electrical people have opinions :angel: just ask your significant other:ashamed1:, that although it is a parallel circuit, it is not, by definition of 310.10(H) conductors joined to form a single conductor, after all you also have 3 sensors with slightly different electrical properties in each branch.:roll:

That's my opinion, and that's all that matters to me. iwire can have his own opinion, and although I don't agree, I can agree to disagree. :p
 

kwired

Electron manager
Location
NE Nebraska
As I like to think iwire is usually on target :sleep:and typically I am in agreement with his points :thumbsup: of view; I have to take opposites sides here.:cry:

If referring to parallel in the pure form of circuit theory, the sensors are individual paths or branches for electrons to flow, thus they do form a parallel circuit. But how does that apply to conductors in parallel :?

So, it is my opinion, and we all know electrical people have opinions :angel: just ask your significant other:ashamed1:, that although it is a parallel circuit, it is not, by definition of 310.10(H) conductors joined to form a single conductor, after all you also have 3 sensors with slightly different electrical properties in each branch.:roll:

That's my opinion, and that's all that matters to me. iwire can have his own opinion, and although I don't agree, I can agree to disagree. :p
Kind of been my conclusion in the past on this topic. I don't think NEC intended for this rule to apply to conductors that are not "in parallel" for the purpose of making a single conductor with a higher ampacity. You must also consider the fact that if the circuit in question is 14 AWG on a 15 amp overcurrent device, the current is still limited to the ampacity of either conductor as opposed to putting two 14 AWG in parallel and expecting to make a 30 amp circuit out of it.

Bob can have his opinion, I can have mine. I do see where his point of view comes from, others have said essentially what I just said, and I can see where that point of view comes from also. If anything NEC needs to clear this up somehow, but I also don't see it being easy to get that done no matter which way it may end up being worded in the end, you will need to propose some pretty impressive wording IMO or they will just say it is fine the way has been for a long time now.
 

PetrosA

Senior Member
The code says electrically joined at each end not mechanically joined.
You are correct. For that state to exist there has to be a mechanical connection at both ends, though. With the design discussed here, there is not a connection (mechanical or electrical) at both ends of the two conductors. Assuming a three wire cable and any number of sensors, the feed (a two wire) originates at a panel, switch, photocell or timeclock - first end. The feed ends at the last sensor, with the load side taken via two wire cable to the lights (other end). You could say that a "portion" of the circuit is in parallel at various times, but not the entire circuit and the electrical connection only exists between the activated sensor and the load - not back to the feed at any point other than at an activated sensor.
 

kwired

Electron manager
Location
NE Nebraska
You are correct. For that state to exist there has to be a mechanical connection at both ends, though. With the design discussed here, there is not a connection (mechanical or electrical) at both ends of the two conductors. Assuming a three wire cable and any number of sensors, the feed (a two wire) originates at a panel, switch, photocell or timeclock - first end. The feed ends at the last sensor, with the load side taken via two wire cable to the lights (other end). You could say that a "portion" of the circuit is in parallel at various times, but not the entire circuit and the electrical connection only exists between the activated sensor and the load - not back to the feed at any point other than at an activated sensor.

When using parallel conductors for the purpose of making an equivalent larger conductor - nothing says the entire circuit must be parallel conductor. You could start out from a 400 amp breaker with two sets of 3/0 for use as a single conductor, land in a junction point then leave that junction point with 500kcmil.

IMO 310.10(H) is intended to apply to conductors that are joined together to make a higher ampacity conductor out of the set, there can be incidents where they are otherwise joined together, like for the purpose of controlling a load from multiple switches like we have here. We have three conductors (I think in OP) that would be parallel to one another. Lets say they are 15 amp conductors on a 15 amp circuit. We did not connect them the way we did in an effort to try to make a 45 amp conductor out of them, none of them are going to carry more than 15 amps without tripping the 15 amp overcurrent device.
 

ronaldrc

Senior Member
Location
Tennessee
is this why the forum usually eliminates "how to" questions?

Yes" They don't have a correct answer because every thing is wrong when you say it is a code violation to parallel
circuits.

Everything in the Electrical construction trade is wired in Parallel with a few exceptions like christmas lights.

Ronald :)
 
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