Diwali lights tripping the MCB? Safety guide for homes in Bengal, Bihar, Sikkim, Assam, Nepal and Bhutan

Before Diwali and Kali Puja, test your RCCB, buy ISI-marked LED serial lights and extension boards, and spread the lights over more than one circuit. Keep every outdoor joint dry and away from metal grills. If the MCB still trips, do not fit a bigger one — find the fault first.

Diwali falls on Sunday, 8 November 2026, so this week is the right time to check. From Kolkata and Siliguri to Patna, Gangtok, Guwahati, Kathmandu and Thimphu, most festive power trouble at home comes down to the same few mistakes. This guide covers them in plain words.

Why does the MCB trip when the Diwali lights go on?

An MCB or RCCB that trips is doing its job. It is telling you something is wrong. There are three usual reasons.

1. Overload. Too many lights, plus an iron, heater or mixer, all on one circuit. The MCB trips after a few minutes.
2. Short circuit. A cut wire, a crushed plug or a badly twisted joint. The MCB trips the moment you switch on.
3. Earth leakage. Current is leaking to earth, usually through water in an outdoor joint or a wire touching a wet wall or grill. This trips the RCCB, not the MCB.

Use this table to find the cause quickly.

What happens	Likely cause	What to do
Light circuit MCB trips after a few minutes	Overload	Move some light sets to another circuit. Do not run a heater or iron on the same circuit.
MCB trips the second you switch on	Short circuit	Unplug all sets. Plug them back one by one. Throw away the set that trips it.
RCCB trips, mostly at night or after dew or rain	Earth leakage from a wet joint	Dry the joint, insulate it properly, lift it off the ground and off metal grills.
Nothing trips, but the plug or board gets hot	Loose contact or overloaded board	Switch off and replace the board or plug. Heat is a warning, never ignore it.
RCCB does not trip when you press its TEST button	Faulty RCCB	Call a licensed electrician to check and replace it before the festival.

If you are not sure which breaker is which, our guide to MCB, RCCB, RCBO and MCCB explains each one.

How much can one socket or extension board take?

Look at the rating printed on the socket or board. In Indian homes, ordinary sockets are usually 6 A and power sockets 16 A. Extension boards also carry their rating on the back or the box.

To check your load, add up the watts printed on each light set and gadget. Then divide by 230 (our supply voltage) to get amps. For example, 1,000 W ÷ 230 = about 4.3 A. Keep the total well below the board’s rating, not right at the edge.

A few simple rules:

• LED serial lights draw very little power. Old bulb strings and halogen focus lights draw much more. Switching to LED is the easiest way to stop overload trips.
• Never plug one extension board into another. Chained boards overheat at the joints.
• Do not run a room heater, geyser or iron from the same board as your festive lights.
• Use a board with a proper plug, a switch and a built-in fuse or breaker. Avoid boards with loose sockets where the plug wobbles.

Do you really need an RCCB for festive lighting?

Yes. An MCB protects the wire from overload and short circuit. It does not protect a person from shock. A 30 mA RCCB does. It cuts the supply when it senses current leaking to earth, for example through a person touching a live grill.

Festive lighting adds a lot of temporary wiring outdoors, on balconies, terraces and gates. That is exactly where leakage and shock risk go up. So:

• Press the TEST button on your RCCB now. It should trip at once. Switch it back on after.
• If it does not trip, or your home has no RCCB at all, get a licensed electrician to fit one. RCCBs for homes are made to IS 12640.
• If the RCCB keeps tripping only when the outdoor lights are on, the problem is in those lights or joints. Do not remove the RCCB.

How do you pick safe serial lights and extension boards?

Cheap unbranded lights and boards are the biggest cause of trouble during the festive rush. Here is what to check before buying:

• ISI mark with a licence number. Many electrical products sold in India must carry the ISI mark. Next to it you will find a CM/L number. You can check that number in the BIS Care app, which shows the licence holder’s details. The same app lets you report misuse of the mark.
• LED products may carry an R-number instead. Some electronic items, including many LED products, are registered under a different BIS scheme and show an R-number. The BIS Care app can verify that too.
• Wire and plug quality. The wire should feel firm, not paper-thin. The plug should be a moulded plug, never bare wire ends.
• A known brand from an authorised dealer. Shree Shyam Suppliers is an authorised dealer for Havells, Lauritz Knudsen (L&T) and Mescab, and also deals in brands like Anchor, Goldmedal, Legrand and Crabtree. Buying from an authorised dealer means you get genuine, traceable products and a bill.

Browse our lighting and fans range to see what we carry.

What are the rules for outdoor lights on balconies, terraces and gates?

Outdoor lights are where most shocks and RCCB trips happen. Follow these rules:

• Keep joints dry and off the ground. Use a proper connector or a small weatherproof box. Do not just twist wires and wrap them in tape.
• Do not tie lights directly on metal grills or gates. If insulation wears through, the whole grill can become live. Use plastic clips or cable ties over the insulation.
• Watch the dew and mist. In Darjeeling, Kalimpong, Gangtok, Shillong, Thimphu and the Nepal hills, outdoor joints get wet at night even when it has not rained. In the plains too, early-winter dew settles on terraces. Check joints in the morning.
• Use lights made for outdoor use. For fittings that stay outside all year, choose an outdoor-rated (IP-rated) light, not an indoor one.
• Keep wires away from where people walk and out of reach of children.
• Switch off before you sleep or leave home. Do not leave temporary lights running unattended all night.

Planning permanent lights or a new outdoor point this year?

Many families use the festival as a reason to add a permanent outdoor socket, gate light or facade lighting. That is a good idea, but do it properly:

• Get a licensed electrician to run a separate circuit with its own MCB from the distribution board.
• Use the right wire size for the load. Our house wire size guide shows the common sizes for lights and sockets.
• Make sure the circuit goes through an RCCB.
• Never take a temporary connection directly from the meter or by hooking onto an overhead line. It is dangerous and illegal.

What should you never do this festive season?

• Never replace a tripping MCB with a higher rating to “stop the problem”. The wire can then overheat and catch fire.
• Never bypass an MCB or RCCB with a piece of wire.
• Never push bare wire ends into a socket.
• Never keep diyas or candles near wiring, curtains or light sets.
• Never cover an extension board with cloth or decorations. It needs air.
• Never ignore a burning smell, a hot plug or a sparking socket. Switch off at the MCB and call an electrician.

Ordering tip

Send us your list on WhatsApp and we will reply with an itemised quote. Include:

• LED serial lights — length and number of sets
• Extension boards — how many and what rating (6 A or 16 A)
• RCCB — if you need one, tell us your main supply (single-phase or 3-phase) and the main switch rating
• Outdoor light fittings, weatherproof boxes and connectors
• Wire for any new circuit — size in sq mm and length in metres
• Your preferred brand and your area

Shree Shyam Suppliers keeps stock on hand with same-day dispatch for most orders, and delivers across North Bengal, West Bengal, Sikkim, Bihar, Bhutan and Nepal. For installation, always use a licensed electrician.