Flex Box: What It Is, Which Size to Buy and How to Use It Safely
A flex box is a portable extension socket whose cord winds onto its own body, so power can reach several metres from the nearest wall socket. This guide explains how flex boxes are sized (2x4, 3x4, 2x8), when you need a 2-pin or 3-pin box, what is safe to plug in, and what our Mumbai-made VIYONA flex boxes cost at MRP.
Key takeaways
- What it is: a flex box is a socket on a long flexible cord that winds onto the body. It adds reach, not extra circuits.
- Sizes: in 2x4, 3x4 and 2x8 the second figure is the cord length in metres; the first matches the plug (2-pin or 3-pin) on the models we photograph.
- Earth matters: anything with a three-pin plug or a metal body needs a 3-pin flex box. A 2-pin box has no earth.
- Loads: chargers, lamps, TVs, fans and short tool use are fine. Irons, heaters, kettles, geysers and ACs go on a wall socket.
- Our range: eight VIYONA codes (V2, V-8, V-9), MRP ₹285 to ₹390, made at our works in Andheri East, Mumbai.
What is a flex box?
A flex box is a portable electrical extension socket whose long flexible cord, the “flex”, winds onto its own body, so you can plug it into a wall socket, unwind as much cord as the job needs, use the socket on its face several metres away and wind the cord back for storage.
Shops also call it a flexible box, an extension reel or a cord-reel extension board. It is not a fixed wiring accessory, and it is not the metal or PVC junction box used in concealed wiring, which some people also search for as “flexible box”.
This guide covers how flex boxes are sized, which one suits which job and how to use one without overloading it, with the VIYONA flex boxes we make in Mumbai as worked examples. Where a point is general practice rather than a published figure for our products, it says so.
Flex box electrical sizes: 2x4, 3x4 and 2x8 explained
A flex box size such as 2 x 4 m is two figures: the second is the cord length in metres, and on every model we photograph the first matches the plug, so a 2x4 box has a two-pin plug and a 4-metre cord and a 3x4 box a three-pin plug. A 2 x 8 m box has a two-pin plug and an 8-metre cord.
Our current catalogue lists three sizes: 2 x 4 m, 3 x 4 m and 2 x 8 m. There is no 3x8, so an earthed plug and the longest cord do not come together in one of our boxes.
Cord length: our flex boxes against our spike guards
Bar lengths are catalogued cord lengths in metres, scaled so that 8 m fills the track and rounded to the nearest 5%. All lengths are from our current catalogue.
The size figure is the quickest way to tell a two-pin box from a three-pin one at the counter, but confirm the plug on the box itself.
| Code | Model | Catalogue size | Cord length | MRP |
|---|---|---|---|---|
| 271 | V2 | 2 x 4 m | 4 m | ₹285 |
| 273 | V2 | 3 x 4 m | 4 m | ₹345 |
| 281 | V-8 | 2 x 4 m | 4 m | ₹340 |
| 282 | V-8 | 2 x 8 m | 8 m | ₹390 |
| 283 | V-8 | 3 x 4 m | 4 m | ₹380 |
| 284 | V-9 | 2 x 4 m | 4 m | ₹315 |
| 285 | V-9 | 2 x 8 m | 8 m | ₹390 |
| 286 | V-9 | 3 x 4 m | 4 m | ₹380 |
Electric flex box vs spike guard vs extension board
An electric flex box winds a long cord of 4 m or 8 m onto its own body to add reach, while a spike guard is a flat socket strip on a shorter fixed cord, sold for protecting electronics from voltage spikes. “Extension board” is the loose trade name for either.
Choose a flex box when distance is the problem: a socket in the wrong corner, a terrace, a site with no power point yet. Choose a spike guard for several devices in one place, such as a TV unit or a desk. Our spike guard guide covers that side; the Classic ABS socket spike guard is catalogued with cords of 1.5 m, 3 m and 5 m at MRPs of ₹370 to ₹670.
For a device that stays in one spot, a wall socket is the first choice. A flex box is for reach and temporary use.
Never plug a spike guard into a flex box, or one flex box into another. Chaining adds joints and puts every load on the first wall socket.
Round reel body with a switch and indicator. 2x4 m at ₹285, 3x4 m at ₹345.
All three sizes: 2x4 m at ₹340, 3x4 m at ₹380, 2x8 m at ₹390.
Round reel body. 2x4 m at ₹315, 3x4 m at ₹380, 2x8 m at ₹390.
The earthed choice for three-pin plugs: codes 273, 283 and 286.
Our VIYONA flex box range: V2, V-8 and V-9
Our current catalogue has eight flex box codes in three models. The V2 comes as 271 V2 2x4 m flex box at ₹285 and 273 V2 3x4 m flex box at ₹345. The V-8 comes as 281 (2x4 m) at ₹340, 282 (2x8 m) at ₹390 and 283 (3x4 m) at ₹380. The V-9 comes as 284 V-9 2x4 m flex box at ₹315, 285 (2x8 m) at ₹390 and 286 (3x4 m) at ₹380.
In our photographs the V2 and V-9 have a round reel body with the socket on its face, and the V2 face carries a switch and an indicator. Every code is packed 5 per box; the set is on the VIYONA flex box range page. Two older V5 models, 276 V5 2x4 m and 278 V5 3x4 m, still have pages here but are not in the current price list, so ask your dealer about stock.
The cheapest way to add reach is the V2 2x4 m at ₹285. The longest reach is any 2x8 m box at ₹390.
2-pin or 3-pin flex box: which do you need?
Buy a 3-pin flex box if anything you will plug into it has a three-pin plug or a metal body, because only a three-pin plug carries the earth connection from the wall socket to the appliance, while a 2-pin flex box has no earth path and suits two-pin devices such as phone chargers, most lamps and small electronics.
The earth wire carries fault current away if a live wire touches a metal body, so the MCB or RCCB at your board can trip. Running such an appliance from a two-pin extension removes that protection even if the wall socket is earthed.
3-pin: earthed 2-pin: no earth Our earthed choices are the 273 V2 3x4 m at ₹345 and the V-8 283 and V-9 286 at ₹380. For how the board protects those circuits, see our guide to choosing an MCB for home.
Never force a three-pin plug into a two-pin socket, bend its earth pin or use an adaptor to make it fit. That leaves a metal-bodied appliance with no earth.
4 metre or 8 metre cord: choosing the length
Choose the shortest cord that reaches: a 4 m box covers most rooms, desks and shop counters, while an 8 m box is for terraces, gardens, parking areas and sites where the nearest socket is across a hall. Spare cord is just more to unwind and trip over.
Length matters for heat too. As general practice, cord-reel makers tell users to unwind the cord fully before drawing a real load, because cord left coiled on the drum cannot shed heat the way a straight run can. Route it along a wall, not across a doorway, and keep it out from under rugs and furniture legs. If a job needs more than 8 metres, add a socket point rather than a second box.
A cord that feels warm to the touch is carrying too much for how it is laid out. Unplug it, unwind it fully and cut the load.
Do not run the cord under a carpet or mat or through a closed door. Crushed insulation is where cord faults usually start.
What can you plug into a flex box?
A flex box is meant for light and moderate loads such as phone and laptop chargers, routers, lamps, a TV, a table fan and hand tools used for short periods, while heating appliances like irons, heaters, kettles and geysers, and motor loads like washing machines and ACs, belong on a fixed wall socket of the right rating.
Our catalogue does not print an ampere rating against the flex box codes, so check the marked rating on the unit and add up the rating plates of what you plug in. Our guide to 6A vs 16A sockets explains the difference: a 6A socket is for light loads, a 16A socket for heavy ones, and an extension reel is not a 16A point.
Typical household loads, from lightest to heaviest
Bars show the usual order of power draw, not measured values or a test by us. For a real figure, read the wattage on each appliance’s rating plate.
An iron or room heater on an extension reel is the classic overload. Plug it straight into a wall socket.
How to use a flex box safely
Use a flex box safely by unwinding the cord fully, plugging it straight into a wall socket, keeping the total load well within its marked rating, keeping it dry, and switching it off and unplugging it after use, then replacing it at once if the cord, plug or body is ever cracked, cut, melted or taped.
Unwind fully Wall socket only No chaining Keep dry Inspect the cord
Keep the box off wet floors and away from sinks, and pull the plug by its body, never by the cord. If the wall socket sparks, runs hot or holds the plug loosely, fix that first: see our guide to a hot or sparking socket and our electrical safety tips for Indian homes.
A flex box left on and unattended overnight with a heater or charger running is a fire risk. Switch off and unplug when you are done.
Use sockets on a circuit protected by an MCB, so a fault trips the circuit instead of overheating the cord.
Where a flexible extension box earns its place
A flexible extension box earns its place wherever power is needed for a short time somewhere the wiring never planned for.
Festival lights Terrace and garden Shop counter Workbench Renovation site
For electricians and contractors it is a site tool that brings a work lamp and a drill to the spot without a fresh line. At home it fixes the room where the socket is behind the wardrobe. If you use one in the same spot every day, add a proper socket instead: our guide to designing a modern electrical layout covers socket positions room by room, and USB sockets for the switch board take chargers off the extension.
Outdoors, keep the box under cover and off the ground. A flex box is not a weatherproof fitting.
Flex box price: what the MRP tells you
Our flex box MRPs run from ₹285 to ₹390: ₹285 for the V2 2x4 m, ₹315 for the V-9 2x4 m, ₹340 for the V-8 2x4 m, ₹345 for the V2 3x4 m, ₹380 for a 3x4 m V-8 or V-9, and ₹390 for any 2x8 m box, so longer cords and earthed plugs cost more.
MRP of our flex box codes
Bar lengths are MRPs scaled so that ₹390 fills the track, rounded to the nearest 5%. MRPs are from our current catalogue; the counter price may be lower.
MRP is the most a shop may charge, taxes included, and every code’s MRP is in our e-catalogue. The gap between the ₹285 V2 and a ₹390 2x8 m box is mostly cord, so buy 8 m only when the job needs it.
If a flex box is priced far below others of the same size, check the cord thickness, the plug and the markings before you buy.
Checking a flex box before you buy
Before buying, check five things: the plug suits what you will plug in, the cord length suits the job, the rating is marked on the unit, the reel winds smoothly without catching, and the cord is firmly gripped where it leaves the body and enters the plug.
Plug type Cord length Marked rating Smooth reel Cord grip
Plugs should go into the socket face with firm resistance, and a maker’s name and code on the box means there is someone to go back to. Our guide on spotting a fake ISI mark shows how to check any mark printed on an electrical product. If the plug on an old flex box is damaged but the cord is sound, an electrician can fit a new one: our Royal 3-pin plug top is 6A at ₹68 or 16A at ₹110, and our 3-pin plug guide explains which to fit.
A cord with tape over a cut is finished. Replace the flex box; do not repair the cord.
Flex box manufacturer in Mumbai: Vinayak Electricals
Vinayak Electricals is a flex box manufacturer in Mumbai: we have made electrical accessories since 1995, and our VIYONA flex boxes are made 100% in-house at our own works in Marol, Andheri East, our only manufacturing site, under an ISO 9001:2015 certified quality system that covers our catalogue of 2000+ products.
Our quality process, in order
Bars show the order of the five steps every product goes through, not time, cost or test counts. We do not publish test counts or rejection rates.
We do not sell online. Buy from one of our 500+ dealers, by phone or by visiting us; the contact page finds your nearest dealer. Shops wanting to stock the range can read how to become a dealer or distributor; dealer support such as display boards and signboards depends on region and market. The rest of our range is on the products page.
Placing a first order for a shop or a project? Test reports are available on request before you order.
FAQs
What is a flex box in electrical?
What does 2x4 mean on a flex box?
Can I use an iron or a heater on a flex box?
What is the price of a flex box?
What is the difference between a flex box and a spike guard?
Where can I buy VIYONA flex boxes?
Why buyers choose Vinayak Electricals
- We make them. Every VIYONA flex box is made at our own works in Marol, Andheri East, Mumbai, 100% in-house.
- Since 1995. Three decades of making switches, sockets and accessories for Indian homes.
- ISO 9001:2015. A certified quality system and a five-step process from raw material to packing.
- Clear sizes and MRPs. Eight codes, three sizes, every MRP printed in the catalogue.
- Earthed option. A 3x4 m version in every model, for appliances with a three-pin plug.
- 500+ dealers. Buy from a dealer near you, by phone or by visiting; test reports on request before a first order.
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