Question 1

What is an LED light?

Accepted Answer

LED stands for light-emitting diode: a small semiconductor chip that gives out light when current flows through it. An LED light uses a driver to turn 230 V AC mains into the low-voltage DC the chips need. For the same amount of light it uses far less power than an incandescent or CFL lamp, and it lasts much longer.

Question 2

Should I compare LED lights by watts or by lumens?

Accepted Answer

By lumens. Watts tell you how much electricity a light uses; lumens tell you how much light it gives. Two 12 W panels can give quite different amounts of light depending on how efficient they are, so pick by the lumen figure and use lumens per watt (lm/W) to compare efficiency.

Question 3

How many lumens does a 9 W LED bulb give?

Accepted Answer

A typical 9 W LED bulb gives somewhere around 800–950 lumens — roughly what a 60 W incandescent bulb used to give. Efficiency varies between products, so check the lumen figure printed on the pack of the exact bulb.

Question 4

What does lm/W (efficacy) mean on an LED light?

Accepted Answer

Lumens per watt is how efficiently a light turns electricity into light. Higher is better. Many LED lamps today are in the region of 90–120 lm/W, compared with roughly 10–15 lm/W for old incandescent bulbs and 50–70 lm/W for CFLs.

Question 5

What is colour temperature (kelvin) in LED lights?

Accepted Answer

Colour temperature, in kelvin (K), describes how warm or cool white light looks: about 2700–3000K is warm white (yellowish), around 4000K is neutral white, and 5700–6500K is cool daylight (bluish white). It changes the feel of a room, not the amount of light.

Question 6

Which colour temperature is best for a bedroom?

Accepted Answer

Warm white (2700–3000K) is the usual choice for bedrooms because it feels relaxing in the evening. If you also read or work there, add a neutral-white (around 4000K) task light at the desk or bedside.

Question 7

Which colour temperature is best for a kitchen, study or bathroom?

Accepted Answer

Neutral white, around 4000K, is a good balance for kitchens, studies and bathrooms: crisp enough to see detail without feeling harsh. Cool daylight (5700–6500K) suits garages, workshops, warehouses and shops that want a bright, clean look.

Question 8

What is CRI and does it matter for home lighting?

Accepted Answer

CRI (colour rendering index, 0–100) measures how naturally a light shows colours compared with daylight. CRI 80 or more is fine for most homes. Choose CRI 90+ where colour matters — clothing and jewellery shops, salons, studios, and kitchens where you judge food.

Question 9

What does an LED driver do?

Accepted Answer

The driver is the small electronic power supply that converts 230 V AC into the steady DC current the LED chips need, and protects them from supply swings. A good driver is the main reason one LED light lasts for years while another fails early.

Question 10

Why do my LED lights flicker?

Accepted Answer

Flicker usually comes from a low-quality or failing driver, a loose connection, an LED that isn't compatible with the dimmer it's on, or a poor neutral connection in the wiring. If several lights flicker at once, get the supply voltage and neutral connections checked.

Question 11

Why does my LED glow faintly when it's switched off?

Accepted Answer

A dim glow after switching off usually means the switch is breaking the neutral instead of the phase, a switch with a neon indicator or a smart switch is passing a tiny current through the light, or long wires running side by side are inducing a small voltage. Make sure switches are on the phase wire; an electrician can add a small bypass capacitor where needed.

Question 12

How long do LED lights last?

Accepted Answer

LED chips themselves can run for tens of thousands of hours, but a fitting's real life depends on its driver and how hot it runs. Good ventilation, a stable supply and a quality driver matter more than the hour figure on the box. LEDs usually dim slowly with age rather than failing suddenly.

Question 13

Do LED lights get hot?

Accepted Answer

Much less than old bulbs, but the chips and driver still make heat, which the fitting's metal body spreads away. Don't cover fittings with insulation or seal them into tight spaces — heat is the main thing that shortens LED life.

Question 14

Can I use LED lights with a dimmer?

Accepted Answer

Only if the LED is marked dimmable, and only with a dimmer made for LEDs. A non-dimmable LED on a dimmer may flicker, buzz or fail early. Fan regulators and old resistive dimmers must not be used to dim LED lights.

Question 15

Are LED lights safe for the eyes?

Accepted Answer

Good-quality LED lights with a proper diffuser and a low-flicker driver are comfortable for everyday use. Avoid looking straight at bare chips, choose diffused or anti-glare fittings for living spaces, and use warmer light in the evening.

Question 16

What's the difference between an LED bulb and an LED panel?

Accepted Answer

A bulb fits into a lamp holder (B22 or E27) and spreads light all around; a panel is a flat fitting fixed into or onto the ceiling that throws wide, even light downwards. Panels suit general room lighting; bulbs suit existing holders, pendants and lamps.

Question 17

How much electricity does switching to LED save?

Accepted Answer

An LED gives the same light as an incandescent bulb for roughly an eighth to a sixth of the power, and about half the power of a CFL. Replacing one 60 W bulb with a 9 W LED that's on 6 hours a day saves about 9 units (kWh) a month.

Question 18

What is the beam angle of a light?

Accepted Answer

Beam angle is how wide the light spreads, in degrees. Narrow beams (about 15–24°) are for accents and highlighting, medium beams (about 36–40°) for display spotlights, and wide beams (60–120°) for general lighting. COB spots usually have narrower beams; panels spread very wide.

Question 19

What's the difference between COB and SMD LEDs?

Accepted Answer

COB (chip-on-board) packs many LED chips into one small, bright source behind a reflector, giving a focused beam and crisp shadows — ideal for spotlights. SMD LEDs are many small packages spread across a board, giving wide, even light — ideal for panels, battens and strips.

Question 20

What is lux?

Accepted Answer

Lux is the amount of light landing on a surface: one lumen spread over one square metre. Rooms are designed in lux — roughly 100–200 lux in bedrooms and living rooms, 200–300 lux in kitchens and 300–500 lux on study and office desks.

Question 21

How many LED lights do I need for a 10×10 ft room?

Accepted Answer

A 10 × 10 ft room is about 9.3 m². For around 150 lux you need roughly 150 × 9.3 ÷ 0.5 ≈ 2,800 lumens from the fittings — about three 12 W panels or downlights giving around 1,000 lumens each. Use the lumen figure of the actual product.

Question 22

Is cool white brighter than warm white?

Accepted Answer

Not for the same lumens. Cool white can look sharper and brighter to the eye, but a warm-white and a cool-white light with the same lumen rating give the same amount of light. Warm-white versions of some products have slightly lower lumens, so check the exact version.

Question 23

What is a 3-in-1 (colour-changing) LED light?

Accepted Answer

A 3-in-1 or CCT-changing light can switch between warm, neutral and cool white — usually by flicking the wall switch off and on again quickly, or with a remote. One fitting can then suit different moods and times of day.

Question 24

Do LED lights attract fewer insects?

Accepted Answer

Generally yes. Insects are drawn mostly to ultraviolet and blue-rich light; LEDs give off almost no UV, and warm-white LEDs attract fewer insects than cool-white ones. Use warm white for porches, balconies and gates.

Question 25

Can I replace a CFL or tube light with LED?

Accepted Answer

Yes. LED bulbs fit the same B22 or E27 holders as CFLs. For old fluorescent tube fittings, it's simplest and safest to replace the whole fitting with an LED batten — no choke or starter is needed.

Question 26

What is surge protection in an LED light?

Accepted Answer

Surge protection lets the driver survive short voltage spikes from lightning or heavy switching on the line. It matters most for outdoor, flood and street lights and in areas with an unstable supply. Check the surge rating (in kV) on the datasheet for outdoor fittings.

Question 27

Why did my LED light fail so quickly?

Accepted Answer

The usual causes are heat (enclosed or badly ventilated fittings), voltage spikes or a loose neutral in the building, water getting into outdoor lights, and low-quality drivers. If many lights fail in the same house, get the supply voltage and the neutral connections checked.

Question 28

Does switching LED lights on and off often shorten their life?

Accepted Answer

No. Unlike old CFLs and tube lights, LEDs aren't worn out by frequent switching. Switch them off whenever you leave a room.

Question 29

Which Indian standards apply to LED lamps and fittings?

Accepted Answer

Self-ballasted LED lamps (bulbs) are covered by IS 16102, LED luminaires (fittings) by IS 10322, and LED modules by IS 16103. LED lighting products sold in India come under BIS's Compulsory Registration Scheme, so look for the BIS registration number on the pack.

Question 30

What does power factor mean on an LED light?

Accepted Answer

Power factor (0 to 1) shows how effectively a device uses the current it draws. Drivers with a power factor of 0.9 or above draw less current for the same watts, which matters in shops and offices with many fittings on one circuit.