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BCH_COLIN 01-22-2011 12:05 PM

Adding 2 more lights to existing light
My first post totally new to electrical work.

I would like to add 2 more lights to an existing fluorescent light (T12). It is connected to a switch but I'm not sure if the wiring is "power through light" or "power through switch" as the cables are like spaghetti in the junction box where they all are found. The switch is located at the end of one of these cables leading from the junction box. The existing light is at the end of another one of these cables leading from the same junction box. Plus there are several other cables leading to other lights, receptacles and switches jammed into this junction box, hence the spaghetti. Some may even be on different circuits.

I tried adding the 2 lights but they don't work. Here's what I did:
On the cable leading from the junction box to the existing light, I added a junction box midway and lead 14/2 cable to the location of the second light and 14/2 cable to the existing light fixture. Just before the location of the second light (fluorescent T8) I added a junction box and lead 14/2 cable to the location of the third light (incandescent) and 14/2 cable to the T8 light fixture. At the third light I attached the cable to the light fixture. I attached all the black cables together and all the white cables together (3 in each junction box, 2 in each fixture) and all the ground wires together (and then to fixtures as well as to junction boxes).

I turned the breaker back on and the exiting light works as usual, but the new lights don't. I'm thinking that I must have the wiring wrong. The T8 and the incandescent fixtures are brand new. Even if the T8 is faulty, would this cause the third light to not work as well? Or is it a problem of mixing different types of lights together? Or will I need to determine if the wiring is "power through light" or "power through switch". I'm not sure how to determine this. Any suggestions would be appreciated.

darren 01-22-2011 12:37 PM

Open up the switch and see if you have only two wires at the switch(white and black). If this is the case you have a switch loop and will have to make joints according in the box.

AllanJ 01-22-2011 01:20 PM

The most straightforward and quite foolproof method is to connect the cable for the new lights right at the first light. Or at an existing junction box that includes a cable that goes only to the first light. Connect the new cable leads to the cable or leads that actually go to the first light, matching the whites and the blacks, without disconnecting other leads (power leads, etc).

It was not a good idea to cut a cable and put a junction box in between. In your case the cable you cut turned out to be inappropriate for the purpose and you must leave the new junction box there while you rejoin the wire leads from the cut cable ends.

BCH_COLIN 01-22-2011 02:48 PM

2 Attachment(s)
Thanks for your replies.

Here are photos of the existing spaghetti junction box and the new junction box I added. I should have included these with my first post.

The existing fluorescent light fixture had the existing cable connected directly inside the fixture, no junction box above it. Should I add the new cable for the 2nd light inside the existing light fixture too? As mentioned, I would remove this new cable from the junction box I added. The switch has a black wire and a white wire. Does this change the wiring needed to add the second and third lights? By the way, this is a really old house as you can see from the photos. The orange 14/2 cable was found in the basement, it's old but appeared to be okay.

Saturday Cowboy 01-23-2011 04:16 AM

outside of a few staples the wiring you show looks ok. We should be able to make this work as shown. So I am making the assumption that we miss wired something. we can't rule out bad fixtures/wrong bulbs/bad install. That main jbox is over box fill, putting an extendstion ring on it would take care of that code violation.

As the switch has only two wires this is power thru light.

I am curious to know why there are two cables labeled incoming power.

I am hoping most of the wiring is visible or you can guess where it goes.

Lets make some sense of the spaghetti:

the incoming cable from the breaker is our HOT. we could find this by testing if we needed to. This incoming white would be our "king" neutral. there would most likely be a large number of whites on this connection.

any cables to a recp or jboxes continuing the circuit would be hooked straight up(white to white, black to black)

the cable going to the switch would have its WHITE marked to indicate that is not a neutral and hooked up to the king hot in our pasta jbox. the black wire coming back from the switch is our SWITCH LEG, it will be connected to the black wire going to any light we wish that switch to control.

the cable going to the light jboxes will have its white to king neutral and black to switch leg.

there maybe a lot going on in this box but don't let that scare you, just take yuor time and do a little muttering and you can figure it out.

AllanJ 01-23-2011 08:41 AM

I'll take a step back and try my idea again.

You have the white power feed cable from Spaghetti leading to a junction box with an orange cable to the original light and another orange cable to the second light. I take it that the white cable used to go directly into the original light.

Come to think about it, it is better to add another light by using a junction box as you have done instead of string the new cable from the original light 1 to light 2 into the body of the original light. Unless the instructions for the light specifically allow that.

The original light still works.

In that junction box the blacks from all three cables are connected togehter and the whites from all three cables are connected together.

Somehow I think it should ALL work unless the next junction box between lights 2 and 3 has some mistake.

A little off topic. I kinda think that the Spaghetti box should have an extension ring (looks like another box of the same size except with no bottom) put on it to give more room for the spaghetti. Things may have been different when the box was first installed but I figure you need 32 cubic inches of space inside. One point for each non-ground wire end (seven cables, two wires each). One point for all the ground wires. One point for all the wire clamps/nipples). 16 points times 2 cubic inches per point for 14 gauge wires equals 32. Do not crank down the wire clamps too harshly on plastic jacketed cables, you should barely squeeze them.

BCH_COLIN 01-23-2011 11:14 PM

Thanks for your great information and suggestions. I rechecked the wiring and made sure my connections were secure. I found a couple of wires in the 2nd new junction box that were a bit loose. I redid the wire nuts and all the lights work fine now.

My guess is the 2 incoming cables from the power source are from 2 breakers. These lights I worked on are on 1 breaker. I will have to open the breaker panel to see where the other cable goes to. There is more spaghetti to come I'm sure.

AllanJ 01-24-2011 11:04 AM

It's okay for two power feeds to enter the same box. But the neutrals must feed only the lights and other things that the corresponding hot feeds, and neither the neutrals of the two feed cables nor the hots of the two feed cables may be commingled.

Exception: Switched 14-2 or similar feeds for fan and light come to the ceiling box and the fan/light unit has only one (shared) white lead. Here both switched feeds must have been on the same branch circuit and you go ahead and connect both feed neutrals to the single fan white lead.

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