Lampshades are attached to a light fitting using the lampshade's 'fitter'. This term covers all of the ways to fix a lampshade to a light fitting.
Lamp shade fitters are the scaffolding or framework inside a lamp shade that allows it to sit in the proper position on a light fitting. Like everything in lighting, there are multiple systems in use so it’s not guaranteed that any lampshade will fit any light.
A 'gimbal' is the framework that attaches to the light fitting in order to support a lampshade. The gimbal includes a ring or washer, which fits over the lamp holder. This is called a 'gimbal ring', and it fits directly over the bulb holder in a light fitting.
The bulb holder in the light fitting will have an external screw thread and a 'shade ring' that is tightened down to secure the gimbal in place.
Some lampshades have a built-in gimbal, where the metal framework is part of the lampshade. This is common in the UK and especially for smaller shades (30 cm or less).
A built-in gimbal means that you don't need to worry about shade carriers or spiders etc as the shade fits directly to the light.
A fixed gimbal means that the gimbal ring is held in a fixed position inside the lamp shade.
Some lampshades have a top and bottom, rather than being symmetrical. In this case, a fixed gimbal is suitable for a ceiling pendant, or a table / floor light but not both because it would be upside down.A fixed gimbal ring at the top of a lamp shade is for a ceiling pendant, and a fixed gimbal ring at the bottom of a shade is for table and floor lights.
Some light shades have a reversible gimbal. This means they can be used on ceiling pendants and table or floor lights.
The gimbal framework inside the lamp shade includes a folding mechanism to position the gimbal ring at the top or the bottom of the shade.
Gimbal ring: the hole at the bottom of the lampshade gimbal that fits over the bulb holder.
There are two common sizes for the external screw thread of lamp holders, so there are two matching gimbal ring sizes.
The large gimbal ring size is approximately 40 mm. This is also known as an ES ring, E27 ring, or Euro ring. This is the most common size as it fits over bulb holders for E27 light bulbs
The smaller size is approximately 29 mm, also known as a ‘UNO ring’, ‘BC ring’, ‘B22 ring’, ‘SES ring’ or ‘E14 ring’. It fits standard UK bulb holders that use bayonet or small screw light bulbs.
Many light shades have the larger 40 mm gimbal ring and are also supplied with a reducer adapter ring that clips inside the gimbal ring to make it compatible with smaller, bayonet or small screw lamp holders.
Duplex lampshades are more common for larger shades with a diameter of 30 cm or more.
It’s called a ‘duplex’ system because the top of a duplex light shade has two rings. The outer ring holds the top of the fabric of the shade and is connected to a second, 11 cm, inner ring that supports the lampshade on the light fitting.
The inner ring fits on to a shade carrier or spider, which is fixed to the light fitting.
On table and floor lights the duplex ring will sit on a shade carrier. With a ceiling pendant light the duplex ring shade will hang on a 'spider'.
Spiders and carriers are fixed to the light fitting using the bulb holder's shade ring, in the same way as a lampshade with a built-in gimbal (see above).
Shade carriers are available in various heights to position the lampshade higher or lower. Usually, taller light shades require taller shade carriers.
You should try to choose a height of shade carrier to position the lampshade so that the light bulb is vertically centred inside the shade.
Lampshades with a clip-on fitter attach directly to the light bulb.
The only complication is that some clips are longer, designed to fit onto candle light bulbs, while others are wider, designed for round light bulbs.
Harp fittings are often used on American table and floor lights as well as tiffany-style table lights with heavier glass shades.
The ‘harp’ is a framework which is part of the light fitting. It includes a central mounting point at the top for the shade to attach to. To fit onto a standard harp, light shades require a 10mm ring which is clamped to the top of the harp using the harp’s decorative finial.
It’s also possible to fit a duplex lampshade to a harp using a harp spider adapter. The spider adapter fits to the top of the harp and provides horizontal legs for the duplex shade ring to rest on.
If you need a bit more information to untangle the lampshade fitters, gimbals, spiders, and rings, please contact My Green Lighting and we'll be happy to help. Alternatively, visit our showroom.
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