Unusual Problem

[karl riley]

Re: Unusual Problem

Please consider that a loop circuit, allowing neutral to split and go back both ways, can create a huge magnetic field in a large area.

I saw the results of a distribution loop in a circular subdivision in Florida where two lines fed the subdivision. The ends of the lines (underground) were across the street from each other, and so they bonded between the neutrals, causing a large magnetic field in the subdivision. The utility did not want to discuss it.

I do think the loop is a parallel path and violates 310-4.

Karl

 

[hurk27]

Re: Unusual Problem

Something does not sound right. A loss of voltage is because of resistance in the wire. Resistance is current limiting 21 bulbs @ 40 watts would only be 840 watts. with the resistance in this circuit it would be even less this should not trip a 15 amp breaker unless there is leakage from the hot to earth loading the circuit even more. thus would give reasone for the breaker tripping and the smoke. I would do a resistance check on the feeds to the poles to see if there is a hot to earth connection. I had a problem just like this the home owner was complaining that the last lights in a long run was about half brite. then the breaker started blowing. but the ground out was almost at the end of the run it caused the voltage drop to magnifiy even more.

[ August 18, 2003, 09:32 PM: Message edited by: hurk27 ]

 

[roger]

Re: Unusual Problem

Karl, I must ask, in a true ring circuit, no spurs, and all loads with no faults, (being even across hot and grounded conductor, no imbalance) how would we have a high magnetic field if the rules of AC going and coming (conductors side by side or even twisted if in a conduit) would cancel itself.

Let's use a single load dead center of the ring for the conversation.

This is a sincere question.

I am starting a new thread with this same post and I appologize to all for threadjacking

Roger

[ August 18, 2003, 09:36 PM: Message edited by: roger ]

 

[charlie tuna]

Re: Unusual Problem

replace the lamps with flourescent retrofit ballasted lamps - this will give you more light and the wattage is only 13 watts per lamp-- this will bring you inside 6% vd...

 

[karl riley]

Re: Unusual Problem

Roger, we are developing a complex thread here. If the extra neutral ran with all the other conductors then it would not create a loop magnetic field. Though it would be a paralleled neutral and still violate 310-4 as I see it. I assumed the ring neutral would travel in a separate path, but maybe the diagram gave me this idea.

Karl

 

[templdl]

Re: Unusual Problem

If your client has a few extra bucks he doesn't mins parting with you may want to consider this.
If one were to get real fancy you could increase the voltage with a step up transformer on the front end to 240 or even 480v assuming that the UF is 600v rated. Then use a step down transformer to 120v at each light post.
by decreasing the amps t0 50% or 25% of what it would be at 120a you greatly reduce voltage drop.