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Shared Neutral on multi-conductor cable


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We have a situation that we're looking to fix for this year. We're using a 16 channel LOR1602W g3 controller to light up 16 trees that are about 300 feet in each direction from the controller. The lights are 15 strands of LED's. Total amp draw per channel is about  just at 1 amp. Last year we ran multiple extension cords from the controller to each tree. This year we're thinking about using (2) 14 gauge 10 conductor cables. Each cable will be approximately 175' long. Within each cable, 8 conductors will lead from each channel on the controller on one end to a 8 individual receptacles on a remote panel. The remaining two conductors will be used as a shared neutral that will be connected together on the panel board and lead back and split again to each channel. We will repeat this with a duplicate setup running the opposite 175'.

 

In theory on the supply to the controller this should be no problem. But we are thinking about trying this on the controller side. Does anyone have any experience with anything like this? I totally understand the importance of not losing the neutral! but not sure if this will work or not.

 

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My system use's 2 shared neutrals for my whole system which is composed of 4 controllers running approx. 45000 lights, i have never had a problem with this arrangement, also what you are wanting to do with your cables is feasable i have done the same thing with my arches and other props on my system, but remember that your wire gauge must support the current draw.

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Thanks for the input. We are doubling the number of neutral conductors to handle the current when all the lights are on and have adequate capacity. My concern was if the controller would act "funky" or have a problem since there no way to guarantee what channel the current will be flowing back on. If all the neutrals share the same buss inside the controller then there shouldn't be an issue.

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That is correct in my system all i feed the controllers is one neutral all my lights go to a main buss i have never had a problem. but remember your neutral wires must be hefty enough to handle the current. on my system i have (3)  8 gauge neutrals going to my main buss and from that 12 gauge feeding the controllers but one neutral wire per controller.

Edited by Godney
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and yes inside the controller the neutral buss is the same remember in your house breaker box their is only 1 neutral buss . and all your house wiring shares that same buss bar same thing with your light wiring. and to let you know  with one neutral to multiple trees it is actually easier to trace down problems less wiring to deal with.

Edited by Godney
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What you are wanting to do is perfectly fine.  Consider you will have a max draw on any 8 channels of 8 amps total.  #14 wire is good for 15 amps.  You need to go up one wire size per hundred feet of cable.  With shared nuertrals you will far exceed you requirement.

 

If you get into heavy current draws the best way it to feed your controller with two 120v inputs from opposite sides (phases) of your panel .  Then take half your outputs in each cable from each side of the controller. That will get you double the ampacity on your nuetral because it only has to carry the imbalance between the two phases.. But that is another discussion... Don't let me confuss your original question.. but for future reference.. there you go..

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I made a 3-channel harness out of 2 runs of SPT-1 wire that runs about 40 feet from a controller to a bush with 3 colors of LED. It has worked fine for years.

 

I also have an 8-channel made out of 4 runs of SPT-1 and one extra wire that connects from a controller with a 9-pin Molex connector to my mega arch.

 

In both cases I use Molex connectors on the controller side and ordinary SPT-1 vampire sockets on the light side.

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What you are wanting to do is perfectly fine.  Consider you will have a max draw on any 8 channels of 8 amps total.  #14 wire is good for 15 amps.  You need to go up one wire size per hundred feet of cable.  With shared nuertrals you will far exceed you requirement.

 

If you get into heavy current draws the best way it to feed your controller with two 120v inputs from opposite sides (phases) of your panel .  Then take half your outputs in each cable from each side of the controller. That will get you double the ampacity on your nuetral because it only has to carry the imbalance between the two phases.. But that is another discussion... Don't let me confuss your original question.. but for future reference.. there you go..

 

I'm not sure, but I don't think the AC controllers like being on different phases because of waveform timing issues.

 

Here's a related post: http://forums.lightorama.com/index.php?/topic/25640-controller-odd-predictable-flashes/?p=241581

 

and: http://forums.lightorama.com/index.php?/topic/26626-did-gen3-controllers-fix-your-dimming-problems/?p=251319

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I'm not sure, but I don't think the AC controllers like being on different phases because of waveform timing issues.

I've never known them to like being on different phases. They get jumpy, and just lose their sense of cool. :)

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We have a situation that we're looking to fix for this year. We're using a 16 channel LOR1602W g3 controller to light up 16 trees that are about 300 feet in each direction from the controller. The lights are 15 strands of LED's. Total amp draw per channel is about  just at 1 amp. Last year we ran multiple extension cords from the controller to each tree. This year we're thinking about using (2) 14 gauge 10 conductor cables. Each cable will be approximately 175' long. Within each cable, 8 conductors will lead from each channel on the controller on one end to a 8 individual receptacles on a remote panel. The remaining two conductors will be used as a shared neutral that will be connected together on the panel board and lead back and split again to each channel. We will repeat this with a duplicate setup running the opposite 175'.

 

In theory on the supply to the controller this should be no problem. But we are thinking about trying this on the controller side. Does anyone have any experience with anything like this? I totally understand the importance of not losing the neutral! but not sure if this will work or not.

 

You are using this controller on a GFI protected circuit, aren't you?

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Ken i happen to agree with Plasmadrive because that is the way my system operates , i am actually using both phases from my panel supplying (4) 120 volt sources to my controller with (3) 8 ga. neutrals and i have never had any problems with waveform  timing or controller issues.

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I'm not sure, but I don't think the AC controllers like being on different phases because of waveform timing issues.

 

Here's a related post: http://forums.lightorama.com/index.php?/topic/25640-controller-odd-predictable-flashes/?p=241581

 

and: http://forums.lightorama.com/index.php?/topic/26626-did-gen3-controllers-fix-your-dimming-problems/?p=251319

The controllers are fine with different phases.  Each phase is exactly 180 deg out of phase with each other so the zero crossing is at the same point. All Triac or SCR based controllers that I have ever seen all reference in one way or another to the zero crossing.  So the phase going pos or neg in reference to the Neut makes no difference what so ever. 

 

There are other factors that can cause issues surely.  Noise is a big one. 

 

I have also run one of my controllers from two legs of three phase power.  I never even thought about it, but it has run for 3 years that way without issue.  So now thinking about it the reason I got away with it is that my home shop has a 240v Delta system and not a 208v Wye system.   With a Delta system I have a "stinger leg" which I can't use because it is about 190v.  The two phases I can use are off a center tapped winding that is used to create the neutral.  So in essence when referenced to Neutal, (center tap) the output of those two legas are 180 deg out of phase with each other.  Works just like standard single phase house power to the controller.

However, regarding what I posted above, to use GFCI on both phases you really need one that is specifically designed for just such a setup. 

The newer spas use a 4 wire system.  L1, L2, N, G.  Some of the things like Ozinators and other accessorties use 120v and the heaters and pumps use 240v.  The GFCI has to know the combination of the L1, L2 and Nuetral so it won't trip when it shouldn't. 

 

But this discussion really doesn't pertain to what the OP asked.  Sorry, I just got carried away.  :P

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I'm not sure, but I don't think the AC controllers like being on different phases because of waveform timing issues.

 

The issue arrises if you connect one controller to 2 different phases of a 3-phase system (120 degrees out of phase), as is commonly found in commercial/industrial buildings. As plasmadrive has found, it is not an issue in single-family homes.

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The issue arrises if you connect one controller to 2 different phases of a 3-phase system (120 degrees out of phase), as is commonly found in commercial/industrial buildings. As plasmadrive has found, it is not an issue in single-family homes.

To clarify one minor point, 2 different phases of a 208v 3ph Wye connected system may not work. The old center tapped 240v 3ph Delta systems, which I have, will work fine. Residential power will also work fine as Steven has pointed out since it as single phase.

 

I just happen to have two power meters at my house, one single phase panel for the house and one 3 phase commerical panel for my shop and well.  ;)

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Steven/Craig: I guess you guys are correct about residential circuits not being a problem with phase, since they're 180 degrees apart.

 

Others have reported problems connecting to three phase circuits.

 

I think the Original Poster was concerned about sharing neutrals, which is OK upstream of any GFIs, but downstream is another matter.

A friend of mine spent time and money building a shared neutral wiring system only to find out it didn't work with a spider box that had built-in GFIs. Oh well.

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I think the Original Poster was concerned about sharing neutrals, which is OK upstream of any GFIs, but downstream is another matter.

 

As long as you don't share neutrals between more than 1 GFCI, you should be ok. As long as all the current that flows out of the GFCI's hot goes back through its neutral, it will not trip.

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One important update regarding this. BE SURE TO USE POLARIZED PLUGS to connect the harness to the controller!!! Otherwise you may have an expensive disaster!

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One important update regarding this. BE SURE TO USE POLARIZED PLUGS to connect the harness to the controller!!! Otherwise you may have an expensive disaster!

Picky Picky Picky.   LOL   :rolleyes:

 

He is right though.. You will let out the secret smoke if you don't be careful. 

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BE SURE TO USE POLARIZED PLUGS

 

I go even further by not using 2-pin plugs for my harnesses:

 

IMG_2528.JPG

The left 8 channels are wired to a 9-pin Molex connector.

 

I also have some 3-channel and 4-channel harnesses:

IMG_1995.JPG

The 4-channel harness doesn't use a common neutral. It just makes the set-up easier.

 

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I didn't read all the above replies, since things seemed to get way off topic.  Sharing neutrals is fine IF you follow the following:

1) You understand what you're doing
2) Ensure the circuits feeding the controller(s) have the correct hot/neutral blade orientation (many outlets are miswired, and this can get VERY dangerous in this situation)
3) Make sure you don't overload the shared neutrals.  They need to be rated to handle the combined load from all hots that are sharing it.
4) As others have noted, don't share neutrals between different GFCIs.  In general, don't share them between "halves" of your controller, unless your controllers only have one plug, or you can guarantee they'll always be plugged into the same outlet (still bad practice).
5) You understand what you're doing. Repeating this one, because this can get dangerous quickly if you don't, both from a "shock hazard" standpoint and a "fire hazard" standpoint, not to mention blowing up equipment.

That said, I do this myself and it works just fine.

Good luck!

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I can't seem to understand why people say your controllers halves cannot share the neutral without problems, when your whole house that means every plug, light ,etc. share only (1) neutral bar in your breaker box , if you open your panel their is (2) power legs (1) neutral bar And (1) gnd. buss now on older homes some share the neutral bar as gnd. and neutral thus showing only 2 power legs and 1 shared gnd/neutral bar. That is why i cannot understand some people saying  you cannot share the neutral between 2 halves of the controller when they come from only 1 buss bar.

Edited by Godney
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I think what they are saying is you can't share neutrals from different phases thru a single GFI, (unless it is made for that purpose like one for a spa).    The controller doesn't care...

 

This whole thing got off track from the OP and it is most likely my fault.  I turned it sideways.. but the discussion is interesting!  :blink:

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I can't seem to understand why people say your controllers halves cannot share the neutral without problems, when your whole house that means every plug, light ,etc. share only (1) neutral bar in your breaker box , if you open your panel their is (2) power legs (1) neutral bar And (1) gnd. buss now on older homes some share the neutral bar as gnd. and neutral thus showing only 2 power legs and 1 shared gnd/neutral bar. That is why i cannot understand some people saying  you cannot share the neutral between 2 halves of the controller when they come from only 1 buss bar.

The GFI outlet will measure the balance of current between the hot and neutral and trip if it's not equal (within a certain tolerance).  If you have the controller plugged into 2 different GFCI's and share neutrals, you'll trip one GFI if not both. 

As I said in my post if the controller is plugged into only one GFI then you're fine. 

With standard residential service what phase you are on don't matter at all, period. 

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