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A World Cord Sets education site

Know the trip before you need it.

A GFCI or RCD compares the current going out with the current coming back and opens the circuit in milliseconds when they differ, because some of it is going through a person. These guides explain the protection in plain language: the trip levels, the reset behaviours, and where the device should sit on the cord. The cords themselves are built and sold by World Cord Sets.

Which protection do I need?Shop GFCI and RCD cords on worldcordsets.com

Which protection do I need?

Where is the outlet, the tool or the water?

1 Where is it?

One tap opens the answer, with the rule that says so.

The library

32 guides to ground-fault protection, written by the people who build it

Every guide, with summaries →
01

Basics

6 guides
02

At home

8 guides
03

On the job

4 guides
04

Around the world

4 guides
05

Troubleshooting

5 guides
06

Portable protection

3 guides
07

Reference

2 guides

Start here

Where the protection sits

Three places to put a ground-fault device, and when each is right

Same protection, different reach and different reset ergonomics.

  • In the plug head

    The whole cord downstream is protected and the TEST / RESET buttons are at the wall. The default for tools, heaters and anything that lives on an extension lead.

  • In-line, partway down the cord

    A module you can reach at the machine, so you reset without walking back to the outlet. Common on equipment leads and hard-wired pigtails.

  • Rewireable (user-attachable)

    Screw terminals instead of a moulded cord: fit the GFCI or RCD to your own cable and give an existing tool protection without replacing its cord.

The two numbers that matter

Trip current. A North American GFCI to UL 943 Class A trips between 4 and 6 mA, the level chosen to protect a person. Portable RCDs in IEC countries trip at 30 mA for general protection and 10 mA where the site or the standard asks for it (schools, hospitals, wet trades). The devices are not interchangeable: different voltage, different trip level, different approval marks.

Reset behaviour. Manual reset stays off after a trip, or after a power cut, until someone presses RESET. Choose it for anything that must not restart on its own: saws, grinders, heaters, pumps in a tank someone may be standing in. Automatic reset comes back when power returns. Choose it for refrigeration, sump pumps and anything that must not stay dead through an outage.

What a GFCI is not

It is not a fuse or a breaker. It does nothing about overload or a short between hot and neutral; it acts only when current takes a path it should not: to earth, through water, through a person. Most GFCI cords therefore sit downstream of an ordinary breaker, and the two protect against different faults.

Where to buy

Every cord explained here is built and stocked by World Cord Sets.

GFCI power cords for North America (NEMA 5-15P, 5-20P, 6-15P, 6-20P, L5 and L6 locking), RCD cords for 230 V countries (Schuko, UK, Italian, Australian), and rewireable GFCI / RCD plug heads and in-line modules, shipped from Connecticut.

Shop GFCI and RCD on worldcordsets.comUser-attachable GFCI and RCD