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Frequently asked questions

Answers to the questions customers ask us most, from choosing and fitting a dimmer to curing flicker. Search, or browse by product or topic.

Showing 18 questions about V-Dim Show all questions

Choosing a dimmer

Which dimmer suits your lights, how much lighting it can take, and dimming from more than one switch.

How many lamps can my dimmer control?

Add up the wattage of all the lamps the dimmer controls: the number of lamps times the watts printed on each. The total must not be more than the maximum load per gang on the dimmer's label and data sheet. For example, 8 LED downlights of 5W each add up to 40W.

DimmerLoad per dimmer (gang)
V-Pro0-120W or 0-300W, no minimum load
V-Pro Multiway, V-Pro Smart120W, no minimum load
V-Pro Multi-Point100W (1 to 10 dimmable LED lamps), no minimum load
V-Pro Micro160W of dimmable LED
V-Com0-100W, 15-180W, 15-220W, 20-400W or 40-600W (the first figure is the minimum)
V-Dim (halogen)Up to 1000W, depending on model; at least 100W recommended: see the V-Dim guide

PowerGrid grid dimmers also have a maximum per plate: single plate (1 to 2 gang) 400W, twin (3 to 4 gang) 800W, double twin (6 to 8 gang) 1200W, triple twin (9 to 12 gang) 1800W, and no more than 800W per row.

With low voltage lighting, add up the VA ratings of the transformers, not the wattage of the bulbs: see transformers and dimmer load. For lamp-by-lamp advice see our compatibility guides.

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Is there a minimum load? Can I dim just one LED lamp?

V-Pro, V-Pro Multiway, V-Pro Smart and V-Pro Multi-Point dimmers have no minimum load, so they can dim a single LED lamp.

Most V-Com and V-Dim dimmers have a minimum: it is the first figure of the rating on the label, for example 20-400W. The 0-100W V-Com has none, and V-Dim dimmers work best with at least 100W. Below the minimum the lights may flicker: see flicker caused by too little load.

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Can I mix lighting types on the same dimmer?

VARILIGHT dimmers are not designed to handle mixed lighting types on a single circuit. This includes combining halogen and LED lamps. With halogen lamps being phased out, most installations now use only dimmable LEDs, which ensures optimal performance and reduces the risk of overload.

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Which dimmer should I use for halogen or filament (incandescent) lamps?

While halogen and incandescent bulbs have been largely phased out in the UK and EU, some dimmers are still compatible for legacy installations. V-Plus dimmers are recommended for halogen, including low voltage halogen on VARILIGHT transformers: their soft start reduces lamp failures at switch-on. V-Dim dimmers also suit mains halogen and incandescent lamps. V-Pro, V-Com and V-Pro Multi-Point dimmers can also be used with mains halogen and incandescent lamps, up to their LED maximum load.

For most modern installations we recommend LED lighting with our LED dimmers, which are optimised for LED lighting. We do not recommend V-Dim dimmers for dimmable LEDs, even if de-rated as some manufacturers suggest.

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Can I use a V-Dim dimmer on a 2-way circuit?

Only a push on/off V-Dim dimmer. Rotary on/off dimmers are only suitable for 1-way circuits.

On a 2-way circuit (the same lights controlled by two switches), choose a push on/off dimmer and replace only one of the switches with it. You can only use one push on/off dimmer in a 2-way circuit, and it must be used with a normal switch. When you switch on a push on/off dimmer the lights come on at the level they were at before they were last switched off.

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How do I work out the dimmer load when there are transformers in the circuit?

Add up the VA ratings of the transformers, not the wattage of the bulbs. Choose transformers with a rating close to their lamp load, e.g. a 50VA, 60VA or 70VA transformer for a 50W low voltage bulb.

  • VARILIGHT transformers: any number, as long as you keep within the maximum rating of the dimmer. For YT40DC12 and YT40DC24 LED drivers, never more than 250W per dimmer circuit.
  • Other brands: use only fully dimmable electronic transformers, and no more than 5 per dimmer circuit.
  • V-Plus dimmers (recommended for halogen on VARILIGHT transformers): load to 75% of the dimmer's maximum.
  • Transformer specifies triac dimming: use a V-Com dimmer.

Wire-wound or toroidal transformers are not suitable for V-Pro, V-Pro Multiway, V-Pro Multi-Point, V-Pro Smart or V-Dim dimmers. If your transformer does not say that it is dimmable it is unlikely to work with any dimmer.

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Can I replace just the dimmer module in my existing plate?

Yes. Our replacement dimmer modules fit into most existing VARILIGHT dimmer plates. Remove the knob (and the front plate, on a Screwless product), unscrew the nut, take the old module out from the back and fit the new one.

RangeReplacement modules
V-Pro (LED)MJP120 0-120W, MJP300 0-300W
V-Com (LED, triac)MKP100 0-100W, MKP180 15-180W, MKP400 20-400W
V-Pro MultiwayMJM100 dimmer, MJS companion controller
V-Dim (halogen)MTP402 60-400W
On/off onlyMH0 2-way, MPINT intermediate

Modules come in different sizes, so check which sizes your faceplate takes: see replacement modules and the Matrix page. Module instructions (PDFs): MJP120, MJP300, MKP100.

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Fitting and wiring

Wiring 2-way and multi-way circuits, wall box depths and where to find the instructions. If in doubt, consult a qualified electrician.

Dimmers

Where can I find the instructions or a wiring diagram for my product?

The instruction leaflet, with its wiring diagrams, comes with your product. You can also find every current leaflet on the instruction leaflets page, and leaflets for older and discontinued products on the earlier leaflets page. Where relevant, check the software version and choose the correct leaflet: the software version is on the side of the dimmer module.

We also have a page of wiring diagrams and how-to videos. Every data sheet links to the product's leaflet: type the product code into the search box. If the wiring diagram is not enough, please contact a qualified electrician.

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What do I need to remove before an insulation test?

Dimmers from all of our ranges should be disconnected for the duration of the insulation resistance test. Failing to do so could damage the dimmer and make the product guarantee invalid.

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Parts, finishes and care

Knobs and spare parts, product codes and data sheets, finishes, cleaning and decorating.

Where can I get a replacement dimmer knob?

All our knobs have the same fixing, so they fit every VARILIGHT dimmer. Screwless products need a "pipped" knob, which is slightly raised for spacing. Pipped knobs aren't sold separately: for a replacement, please send us a message or email help@varilight.co.uk and our customer services team will help.

Spare knobs are sold singly or in packs of 10 (the same code with 10 on the end). Click a code for its data sheet, which shows where to buy it:

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Guarantee and older products

The lifetime guarantee, how to claim, and help for products we no longer make.

How do I make a guarantee claim or return a faulty product?

Many problems can be solved without a replacement, so please check the troubleshooting answers first. Then:

  1. Submit a guarantee claim, or email our support team at help@varilight.co.uk, with your purchase details and a description of the problem. We'll review it and respond within one working day.
  2. Tell us the product code, the batch number (on the plastic moulding at the back of a dimmer), the type and wattage of the lamps it controls, and the fault. Keep your proof of purchase.
  3. The faulty product must be returned to us. We'll email you a reference number, and you can return the product free of charge through the Royal Mail returns portal, using our returns reference (KILNWOOD) and your reference number.

If the claim is approved, we'll arrange a repair or replacement at no cost to you. See our lifetime guarantee.

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One dimmer on my multi-gang plate is faulty: can I keep using the others?

Yes. It is perfectly in order to remove a faulty dimmer module from a multi-gang dimmer by pulling off the knob and unscrewing the nut under the knob (and removing the front plate first, on a Screwless product). You will then still have the remaining modules working while we service the faulty one. See how to make a claim.

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Troubleshooting

Dimmers that have stopped working, flicker, buzz or glow, and other problems with installed products.

Not working, or switching off

My dimmer has stopped working: what should I do?

Many faults can be cleared without replacing anything. Switch off at the mains before touching any wiring and, if in doubt, consult a qualified electrician.

  1. Reset the power. Switch the lighting circuit off at the circuit breaker, then back on after a few seconds. An overloaded dimmer switches itself off to protect itself, and touch and remote dimmers can often be reset this way.
  2. Check the load. Add up the wattage of all the lamps on the dimmer (for low voltage lighting, the VA ratings of the transformers). It must not be more than the maximum per gang on the dimmer's label. See how many lamps a dimmer can take.
  3. Changed the bulbs? If you have changed the type of lamp, reset the dimmer to its factory settings: V-Pro and V-Com, V-Pro Multiway, V-Pro Multi-Point, V-Pro Smart, or V-Pro Micro in set up your dimmer.
  4. New installation? Check the wiring against the diagram in the instruction leaflet. A touch or remote dimmer must have a true live connected to its "Live" terminal: it must not be switching neutral.
  5. Lights come on but won't dim? See my dimmer won't dim the lights.

If it still doesn't work, the dimmer may be faulty. It is covered by our lifetime guarantee: see how to make a claim. It helps to have the product code, the batch number (printed on the plastic moulding at the back of the dimmer) and the type and wattage of your lamps to hand.

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My dimmer turns the lights on and off but won't dim them

V-Pro and V-Com dimmers: we would advise you to perform the factory reset on the dimmer switch. Instructions are also in the product instruction leaflet and on VARILIGHT TV. If you have performed the factory reset and the lights are still not dimming, please contact Customer Services: send us a message or email help@varilight.co.uk.

Other dimmers: this problem is usually caused when one of the components in the dimmer has failed, usually due to a plasma. Plasmas can be caused when a mains halogen light bulb (e.g. GU10) fails. For this reason we recommend only using good quality mains halogen bulbs from well-known brands. If a dimmer shows this fault it will need to be replaced.

The best type of dimmer to use with mains halogen bulbs is a VARILIGHT V-Plus series dimmer. The rapid on-board overload protection can usually turn the dimmer off so quickly that it survives a spike in the mains supply.

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My lights are switching to a reduced brightness

The usual reason is that the dimmer is overloaded. A V-Plus dimmer turns the brightness down, or off, until the overload is removed and it is switched off and on again. V-Pro, V-Com, V-Pro Multi-Point and V-Dim safety dimmers switch off instead until the overload is removed.

Check the maximum load on the label on the back of the dimmer. Add up the wattage of the lamps it controls; with low voltage lighting, add up the VA ratings of the transformers, not the bulbs. If the total is more than the maximum, use fewer or lower-wattage lamps, or a higher-rated dimmer: see how many lamps a dimmer can take.

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Flickering, buzzing and glowing

My dimmer is causing the lights to flicker (minimum load)

This problem is usually caused when the dimmer is under-loaded.

Check the label on the back of the dimmer, where the minimum and maximum load are printed. Add up the ratings of all the light bulbs the dimmer controls and make sure they are more than the minimum. V-Dim dimmers work best with at least 100W. The 0-100W V-Com has no minimum.

If your lighting load is below the minimum, choose a different dimmer or use bulbs with a higher rating: you can still dim them right down. For dimmable LEDs choose a V-Pro dimmer: V-Pro dimmers have no minimum load.

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My dimmer or my lamps are buzzing

It is quite normal for a dimmer switch to buzz a little. A dimmer is more prone to buzz with certain types of lighting load. If your lighting load is causing your dimmer to buzz excessively, we recommend changing the dimmer for a trailing-edge dimmer. Our V-Pro series trailing-edge dimmers are the quietest running dimmers available.

If the LED lamps themselves buzz while a V-Pro dimmer is on, a component within the lamps is vibrating during operation. Changing the driving mode on the dimmer may improve this. If the lamps continue to buzz after trying the different driving modes, we recommend contacting the LED manufacturer for further advice.

With other brands of dimmable electronic transformer, noise levels may vary depending on the type and quantity of transformers used.

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Is it normal for my dimmer to feel warm?

Yes. It is normal for dimmer switches to feel slightly warm during operation, particularly when they are controlling loads close to their maximum rated capacity. During dimming a small amount of heat is generated, and it is intentionally transferred to the front plate through the dimmer module's heat sink. This helps dissipate heat efficiently and protects the internal electronic components.

Touch and remote dimmers also draw a very small standby current when switched off, so they may feel slightly warm even when off. They have over-temperature protection, and the fire retardant material around the electronics at the back may show some discolouration from moderate temperatures, which is expected in normal operation.

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Still stuck?

Our customer services team will help. To get the quickest answer, tell us the product code, the batch number from the back of the dimmer, and the make, wattage and number of lamps.