Transformers! No, not the movie.

[Auntie Jojo]

Hi, Everyone:

New poster here. I didn't see anything else that deals with my problem specifically, so here I am posting a NEW THREAD.

I got a single hardwired halogen mini-pendant, and I'd like to wire it as a plug-in because I want to hang it in a dark corner with no hardwired boxes, and no, I'm not going to punch a hole in the plaster and put a real box there, so that's out. Basically, I'm trying to make a small swag light to light up a corner. The pendant has a 50w transformer in it, and I'm using a 35w halogen bulb.

I have some questions about this, and I'd appreciate some advice from the experienced because I want to be sure about these issues:

1. I've already wired up the 120 v. house wires to the transformer: White to white, black to black. Then we have TWO red low-voltage wires coming out of the transformer. The mini-pendant has a single wire leading to the lamp. How do I wire this properly? Both red wires to the single lamp wire?

2. Is it legal--and more importantly--is it safe--to not have a box and just wire up the lamp cord to the transformer inside the canopy? I realize it's not that much different from a regular lamp, but...I just want to be absolutely sure. I don't know from transformers. I do know they can get warm, and I know halogen bulbs can get warm! Is it OK, what I'm doing? I used nice silicone tape just to be safe. That stuff can get hot and doesn't seem to disintegrate as quickly.

3. This lamp is not wired on a grounded circuit. It's an old house and this was one plug I didn't have grounded (it's a bit out of the way and isn't used much). Is it safe to NOT ground this lamp? Safe enough (given the millions of us who live in old houses with ungrounded circuits)? I will be touching the dimmer switch a lot, I'm sure. I'll try not to be soaking wet when I do so. And it's not in a wet area...

Oh! And....

4. About that dimmer. I've connected one of those nice Lutron on-cord dimmers, the Attache LC-300H with the little red LED so I can find it in the dark. The transformer says it's dimmable. But Lutron says not to use the dimmer with items that are on transformers. Has anyone done this anyway and had OK results? I don't see how you'd use the Lutron dimmer with ANY halogen or LED dimmable lights if it were really true.

I have tested the Lutron dimmer switch--it's getting power. Now I'm working my way up the cord to the lamp, and I got nervous at the transformer because I wasn't 100% sure what to do. Electricity is nothing to mess with.

Thanks, folks.
Jojo

 

[hj]

A bulb HAS to have two distinct wires to it. IF you connect both transformer wires to a single wire you will burn out the transfomer, blow a fuse, or start a fire, and possibly more than one of these could happen. You cannot just reduce the power to a transformer to dim a light, and haloge bulbs also need a special dimmer so the Lutron is out on both counts.

 

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[PatrickH]

Lots of questions about your post. Firstly the house wiring should terminate to the transformer within a suitable electrical box. Many transformers have a 1/2 inch threaded end to facilitate mounting them to an electrical box. Is the an existing outlet in the vicinity that you might be able to plug in a halogen light that comes wired with a plug and transformer from the store?

 

[Auntie Jojo]

A bulb HAS to have two distinct wires to it. IF you connect both transformer wires to a single wire you will burn out the transfomer, blow a fuse, or start a fire, and possibly more than one of these could happen. You cannot just reduce the power to a transformer to dim a light, and haloge bulbs also need a special dimmer so the Lutron is out on both counts.

>>>Yes! This is exactly what I thought. But I promise you, the light fixture (a halogen pendant light with a single 12v, 35w GY6 bulb in it) has only a single wire leading to it. And I don't mean a single split wire, like a lamp cord has, but a single WIRE. I can take a picture and post it tomorrow. It was a real surprise to crack open the canopy and find that. I figured, well, I know nothing about low-voltage applications or halogen lights, so maybe that's how they are...

 

[Auntie Jojo]

Lots of questions about your post. Firstly the house wiring should terminate to the transformer within a suitable electrical box. Many transformers have a 1/2 inch threaded end to facilitate mounting them to an electrical box. Is the an existing outlet in the vicinity that you might be able to plug in a halogen light that comes wired with a plug and transformer from the store?

>>>Yeah, that's what I thought. No, I'm afraid there's no box anywhere nearby. If I wanted to terminate in a box, I'd have to carve up the ceiling. It's in a cold, lonely, empty corner of a 2nd floor room. There is a plug about 12 feet away, though, and I have this nice leftover pendant light. I thought, heck, I'll just wire it to plug in! Then I thought twice. Then I thought, "Sheesh, how come a regular old table lamp can have power coming directly into it from a cord plugged into the wall, but such a setup as I described cannot?" Is it just the transformer that makes the difference?

 

[Auntie Jojo]

Here are some photos of what I'm talking about--a 120v to 12v little transformer, only for halogen lamps. It was glued inside the lamp housing. The pendant light was originally hardwired. Both red wires were connected to something originally, but I can't figure out what! The white/black wires that would go to the house wiring are labeled N and L, respectively, for neutral and load, I assume. They were not connected to anything originally. I of course hooked these up to a polarized 18/2 SPT2, nice beefy lamp cord--correctly.

Note the SINGLE wire that goes, through a metallic decorative covering, down the "pendant" to a little housing that contains the halogen bulb itself.

It's really those two red wires I'm puzzled about. Where do they both go if there is only one lamp wire to attach to? I swear, I have not cut anything or taken anything away. The lamp was given to me as a spare from someone's bar setup, where they have four of them that are hardwired. I just wanted to make this one NOT hardwired, to make it into the equivalent of a swag lamp.

j.

 

[DonL]

That is a Coaxial cable. The shield connects to the lamp fixture.

The shield is the second wire.

One wire to the center conductor, one to the shield.

Be careful playing with electricity.


Good Luck on your project.

 

[Auntie Jojo]

You are right! This is a coaxial cable--I just looked it up and found something about it online. It seems weird to hook up the shield, but I will give it a go. That makes sense--there were two of those squeeze-type splice connector wire nuts in the kit, and the housing/shield was originally connected. I thought, "That can't be right!" But apparently, it is. Do you know why the low voltage wire connects to that weird metallic wire shield? Where does it go?

And yes, I have a *very* healthy level of fear of electricity. I have done a lot of regular lamps, but this is the first halogen I've messed with. When my electrician comes by to put in a new circuit I'll have him check my work just to be sure.

If it doesn't work, I will just convert it with a swag kit or LED kit. Here goes! Results to follow.

THANK YOU.

j.

 

[Auntie Jojo]

I plugged in the lamp, and it did not work. Tried a different, new halogen bulb. Also did not work. After a short interlude with my multimeter, I discovered that the transformer is not working. It's easier, safer, faster, and cheaper to fit a ready-made swag light kit to the glass shade that I liked, so I'll do that. So much for a hacked halogen pendant lamp. One probably shouldn't be "hacking" electricity anyway.

No harm done to anyone, lesson learned, and thank you to all of you who spent time reading and suggesting things. I appreciate it. It was fun to try.