Extension Leads and Cable Reels: Safe Selection

Extension leads and cable reels are workshop essentials. But they're also responsible for thousands of fires every year when misused or poorly chosen. Here's how to select and use them safely.

Understanding Ratings

Current Rating (Amps)

The maximum current the cable can safely carry. Common ratings:

• 5A - Light loads only (lamps, chargers)
• 10A - Medium loads (power tools, heaters)
• 13A - Full capacity for UK plugs

The Coiled Cable Trap

Critical: Cable reels have TWO ratings - coiled and uncoiled. A reel rated 13A uncoiled might only be 5A when coiled. This is because coiled cable can't dissipate heat.

Always check both ratings. If using high-power tools, uncoil fully.

Cable Cross-Section

• 0.75mm² - Light duty, short lengths only
• 1.0mm² - General purpose
• 1.5mm² - Heavy duty, longer runs
• 2.5mm² - Site and industrial use

Thicker cable carries more current with less voltage drop and heat buildup.

Length Considerations

Longer cables = more resistance = more voltage drop. This matters for power tools:

• Up to 10m: Usually fine for most tools
• 10-25m: Use heavier gauge cable
• 25m+: Consider voltage drop, use 2.5mm² minimum

Voltage drop makes tools run slower and hotter. Motors work harder and wear faster.

Extension Lead Types

Household

Light duty, typically 5m-10m, 4-6 sockets. Fine for indoor, dry environments with moderate loads.

Workshop

Heavier cable, robust construction, individual switches often included. Better for tool use.

Outdoor/Site

Weatherproof construction, typically orange for visibility. IP44 rated minimum for outdoor use. Essential for garden tools and site work.

Industrial

Heavy-duty cable, armoured options available, proper site plugs (110V for construction sites).

Cable Reels

Benefits

• Tidy storage
• Long lengths in compact form
• Carry handle for portability
• Often include thermal cutout protection

Things to Check

• Thermal cutout (trips if overheating)
• Number of sockets
• Cable length and gauge
• Both coiled and uncoiled ratings
• Build quality of the reel mechanism

Check our electrical range for quality options.

Safety Features

Thermal Cutout

Trips if the cable overheats. Should be standard on any decent reel. Prevents fires.

RCD Protection

Some leads include built-in RCD (residual current device). Adds protection against electric shock. Essential for outdoor use and wet environments.

Surge Protection

Protects connected equipment from power surges. Worth having for sensitive electronics.

Common Mistakes

Daisy-Chaining

Plugging extension leads into each other. Bad idea. Each connection adds resistance and potential failure points. Use one appropriate lead.

Overloading

Adding up the watts of everything plugged in and exceeding the rating. Calculate your load and respect limits.

Leaving Cables Coiled

Using high-power tools with the cable still on the reel. Uncoil fully for heavy loads.

Damaged Cables

Using leads with cut outer sheathing or damaged plugs. Replace immediately - exposed conductors are fire and shock hazards.

Running Under Carpets

Cables under rugs can't dissipate heat and get damaged by foot traffic. Never do this.

Buying Recommendations

For Workshop Use

25m cable reel, 2.5mm² cable, 4 sockets, thermal cutout. Uncoil for power tools.

For Garden/Outdoor

Weatherproof reel with RCD, IP44 rated minimum, bright colour for visibility.

For General Home

10m lead, 4-6 sockets, surge protection if using for electronics.

Browse our electrical supplies for safe, quality options.