Winter electrical safety at work: portable heaters, extension leads and battery chargers
Why winter increases electrical risk
More plug‑in heaters appear (often personally purchased), driving higher currents on circuits not designed for space heating.
Extension blocks and reels get pressed into service and overloaded or left coiled.
Charging demand rises for laptops, tools and personal micromobility (e‑bike/e‑scooter) batteries, often in unsuitable areas.
Cold, damp conditions increase the chance of insulation breakdown and RCD trips.
Quick answer
Portable heaters: plug directly into a wall socket, keep 1 m clearance from combustibles, never cover or use on an extension reel, and choose models with tilt cut‑out and overheat protection.
Extension leads and reels: avoid daisy‑chains; keep total load under 13 A (≈3,000 W) on a single socket; fully unwind reels under load; prefer RCD‑protected leads.
Battery chargers (laptops, tools, e‑bikes/e‑scooters): use only manufacturer‑approved chargers, charge on non‑combustible, ventilated surfaces, never in escape routes or unattended overnight. Consider a designated charging area for Li‑ion equipment.
Make it routine: add weekly visual checks in winter and record defects. Risk‑based PAT testing supports compliance and reduces downtime.
Portable heaters: how to choose and use safely
Do
Prefer oil‑filled radiators or convectors with:
UKCA/CE mark, BEAB Approved if available
Tip/tilt cut‑out and overheat protection
Thermostat and timer
Plug directly into a wall socket (BS 1363), one heater per socket.
Maintain 1 metre clearance in all directions from paper, fabrics, packaging and furniture.
Place on a flat, stable, non‑combustible surface, away from foot traffic.
Create a simple permit or approval process for heaters in shared areas.
Don’t
Don’t run heaters from extension leads, multi‑way blocks, or reels.
Don’t place under desks, on soft furnishings, or close to curtains/blinds.
Don’t cover heaters with clothing or dry items on them.
Don’t locate in escape routes or near oxygen/flammable storage.
Typical heater loads and what this means for circuits
Appliance type
Typical power (W)
Approximate current at 230 V (A)
Safe practice
Oil‑filled radiator (medium)
1,500 – 2,000
6.5 – 8.7
Plug directly into wall socket; keep 1 m clearance
Fan/convector heater (high)
2,000 – 3,000
8.7 – 13.0
Plug directly into a wall socket; keep 1 m clearance
Desk fan heater (compact)
1,000 – 1,500
4.3 – 6.5
Wall socket; avoid under‑desk placement
Extension leads and reels: the safe way
Do
Use one high‑quality, fused, switched 4‑way block per wall socket, total load ≤ 13 A (≈3,000 W).
Fully unwind cable reels before use; choose heavy‑duty, 13 A reels with thermal cut‑out.
Prefer leads with an in‑line 30 mA RCD, especially in damp/cold areas.
Label blocks with a simple “max watts” card and list typical loads (see table below).
Don’t
Don’t daisy‑chain (block into block, or block into reel).
Don’t exceed the rating of the weakest link (multi‑way strips are often 10 A).
Don’t route cables under carpets/doorways or leave reels coiled under load.
Don’t use cube adapters; remove them from service.
Heaters: wall socket only, 1 m clearance, never covered, stable base.
Extension leads: no daisy‑chains, keep under 13 A total, fully unwind reels.
Chargers: use original chargers, ventilated non‑combustible surfaces, no overnight charging.
Escape routes: keep clear of heaters, leads and charging.
See it, sort it: report damaged plugs, scorched blocks, hot smells, or tripping.
Policy tips for large organisations
Publish an approved heater list and a one‑page user guide. Allow only units that meet your specification.
Ban cube adapters and daisy‑chains site‑wide; empower colleagues to remove them.
Define where charging is allowed by type (office IT vs Li‑ion tools vs micromobility) and when (no overnight without supervision and detection).
Add winter spot checks to local safety tours; record and close out defects.
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FAQ
Q: Is it safe to use a portable heater on an extension lead? A: Best practice is no. Heaters draw high currents that can overheat leads and blocks. Plug directly into a wall socket.
Q: Can I plug multiple high‑load appliances into one 4‑way? A: Keep total load under 13 A (≈3,000 W). Don’t share a block between a heater, kettle or microwave; use separate wall sockets.
Q: Should extension reels be fully unwound? A: Yes. Coiled cable traps heat under load and can overheat. Fully unwind and keep the cable visible.
Q: Can staff charge e‑bikes or e‑scooters at work? A: Only in a designated, risk‑assessed area with controls. Avoid general office charging and never charge in escape routes or overnight.
Q: How often should heaters, leads and chargers be PAT tested? A: Use a risk‑based approach. In offices, low‑risk IT may be 24 months; higher‑risk items like heaters, leads and site chargers are often inspected and tested more frequently. See: https://allinonepropat.co.uk/pat-testing/
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Compliance note Under the Electricity at Work Regulations 1989, employers must maintain electrical systems so they are safe. A risk‑based maintenance regime, including PAT for portable equipment and routine RCD checks, is a practical way to demonstrate compliance.
Need support? If you’d like a winter‑focused PAT sweep with clear labelling, a simple asset register and rapid certificates, book here:
