Introduction: Convert Light Fitting to LED Cluster

About: Lazy engineer.

I've got a lovely old light fitting on the front of my house, but the bulb in it is quite dim. It's a fluorescent which is about a 100w incandescent (filament) equivalent. It also, mostly down to a design flaw in the fitting, casts a shadow right where I need to see my door keys.

I need it brighter.

I can't fit a larger fluorescent in there, and I couldn't go much brighter with an incandescent (nor would I want to - those things make better heaters than lights). I could probably about double the brightness with an LED, but that still wouldn't be enough, and wouldn't solve the harsh shadow directly beneath it.

I'm going to add several LED bulbs for max brightness, min energy use, a pleasing white temperature, and softer, smaller shadows. We're going to achieve around a 1KW incandescent equivalent brightness.

This Instructable will show you how to convert a light fitting, to LED cluster.

Step 1: Gather Your Supplies

I love this step! I mean, you're obviously not going to do this until you've read the entire Instructable. At that point, you've seen the supplies over the following steps, and already got an idea of what you'd change.

It's a good chance to talk about some of the challenges ahead though.

You'll need to mount your cluster. I'm using a nylon chopping board, and a PVC pipe. The pipe will slot over the old fitting, placing my cluster nice and high up. As a bonus, there's loads of reflective, white material. It's also a nice canvas for marking on where you want your new lights.

Luckily, this pipe looks to be about the right length. If you haven't got a correct length piece of pipe, you can make one by cutting a longer pipe down. I expect there's an Instructable for that, but we're not going to go into it here.

I've got for 16 G9 mounts and LED bulbs. This standard is just the right size for corn cob bulbs, so you get the best brightness for your bulb size. 16 bulbs will lay out nicely in a square, which means we can nicely fill our space.

Filling the space so neatly causes a problem. I won't be able to turn the cluster once it's placed on the fitting. I'm converting a bayonet fitting, but if you're converting a screw fitting, you'll have the same issue. We need to place an extra connection between the cluster and the existing fitting.

I'm using what I now know to be called a C7 to C8 cable, but would probably call it a figure-8 extension lead. You might recognise these cables from such low power mains devices as radios, televisions, and other hi-fi equipment. They're safe up to 3 amps. I'm going for about 500mA at 240V, which would be about 1A for the same power at 120V.

Chopped in half, both ends form a new plug and socket. We can not construct two devices - an old fitting to C7, and a C8 to light cluster.

Step 2: Cut Out the Mounting Board

We need to cut small holes round the edge for our new lights, and a larger hole in the middle to run our cables through.

I'm using an electric jigsaw for cutting the board, but you might have access to something that can go in straight lines. Spade bits do a good job of cutting most plastics, but anything designed for wood should be fine.

A 10mm bit is more than I need for the wires from the new light fittings, but it's the smallest spade bit I have. 22mm is spot on for my bayonet fitting. I'm guessing an E27 would be about the same, but measure what you have.

Make sure the hole in the middle is smaller than your pipe. And, if you haven't done already, make sure your pipe will go over your old fitting.

Step 3: Attach a Stand

It may seem odd to make our build to precarious at this point, but I need to be able to work on the wiring without crushing the bulbs. To do that, I need the mounting board off the table.

I'm hot gluing this, because it's going to be outside in a temperate (ie, miserable) country, with no serious load on it. I'm also hot gluing it because I'm lazy - the same reason anyone uses a hot glue gun.

Once the board and pipe are connected (look, it's taking shape!) we can keep them upright with a clamp.

Step 4: Attach the Lights

This part is fairly simple, but slightly laborious.

Each fitting need poking through a hole, and attaching on top. More hot glue.

Then trim the wires down so they just about meet, and stick the bulbs in. You can wait until the end to put the bulbs, but LED bulbs are fairly light and rugged.

Step 5: Construct the Wiring Loom

I'm using terminal strips in pairs as connector. These ones are the largest I've got - perhaps 24A - which I've selected for their size. I can fit four wires into one port on these, that means I can go from 16 lights to four blocks...

Step 6: Add a Power Socket

...then four blocks to one block. Then from one block to our power socket. The wiring loom is complete.

Make sure you use the C7 here (the female end) so you can test your cluster with another figure-8 lead.

I did a visual inspection before I powered it up - all wires connected, all wires firmly held, all copper within the blocks, no sheath within the blocks - and I used a power block with a surge connector. No complicated work with a multi-meter.

It's been a fairly simple wiring job. Treat it like plumbing - be meticulous, check your work, test it, be prepared to quickly switch it back off again.

It works! And you can't be in the same room as it without it burning a purple rhombus onto the back of your eye balls.

Step 7: Install

The last part of the build is to put our adaptor together. That's a C8 to a bayonet plug for me, but obviously you convert whatever you need to.

That bayonet plug feels like it's made of Bakelite, so it's anyone's guess how long it's been sitting around in a warehouse! It's also a nice shade of pre-war brown. If you're converting from E27, there will probably be more options available to you (including E27 to mains socket, which could offer a nice alternative to our figure-8 lead).

The adaptor goes in first. Then place the light cluster over the top, threading the adaptor lead up through the tube. Connect the adaptor to our wiring loom, and switch on the light.

Bright and soft.