IEC vs US electrical symbols, the same plan in two conventions
How European (IEC 60617) and American electrical plans differ, mark by mark and word by word. Sockets and receptacles, two-way and three-way, RCD and GFCI, 230 V and 120 V, A4 and Letter. With a room you can switch between the two.
Electricians rarely change continents, but drawings do. A European firm fits out a client's American office; an Irish electrician gets a plan drawn in Texas; a crew trained in Manila works in Dubai and then in Toronto. The plan in front of them is drawn in a convention they were not trained on, and the first hour is spent decoding it. This page is that hour, written down.
The same room, both ways
One room, drawn with the IEC 60617 symbols that Europe and most of the world use, then with the US symbols descended from the ANSI and NECA standards. Flick between them: the walls, the devices and the circuits do not move. Only the marks and the names in the legend change.
Mark by mark
The marks are mostly one to one. The table shows the common ones side by side, drawn as a plan in each convention shows them. The symbols chart has all 71.
| Device | IEC drawing | US drawing | IEC name | US name |
|---|---|---|---|---|
| Socket, one outlet | Single socket | Single receptacle | ||
| Socket, two outlets | Double socket | Duplex receptacle | ||
| Protected socket | RCD socket | GFCI receptacle | ||
| Switch, one place | One-way switch | Single-pole switch | ||
| Switch, two places | Two-way switch | Three-way switch | ||
| Switch, in the middle | Intermediate switch | Four-way switch | ||
| Light on the ceiling | Ceiling light | Ceiling light | ||
| The board | Distribution board | Panel |
Word by word
The vocabulary is where most of the confusion lives, because the same word can mean different things.
| The thing | Europe says | North America says |
|---|---|---|
| The outlet in the wall | socket, socket outlet | receptacle (an "outlet" is the box) |
| A pair of switches for one light | two-way (by positions) | three-way (by terminals) |
| The switch between the pair | intermediate | four-way |
| The board in a house | distribution board, consumer unit | panel, panelboard |
| The device that trips on earth leakage | RCD, residual current device | GFCI, ground fault circuit interrupter |
| The protective conductor | earth | ground |
| The switched feed for the cooker | cooker control | range outlet |
| A fixed appliance's fused feed | fused spur | a dedicated circuit, often with a disconnect |
The two-way switching article shows the pair working, whichever it is called.
Voltages, and what they do to a plan
| Europe | North America | |
|---|---|---|
| Ordinary circuits | 230 V | 120 V |
| Heavy loads | 400 V three-phase (workshop, large heater) | 240 V (range, dryer, water heater, air conditioning) |
| A 1,500 W heater draws | about 6.5 A | about 12.5 A |
Two consequences. The dedicated 240 V circuits appear as their own symbols on a US plan, the range outlet, the 240 V receptacle, the disconnect, where a European plan shows a cooker control or a fused spur. And any load estimate depends on the voltage: a circuit that is comfortable on one side of the Atlantic is full on the other, which the load calculation article shows with numbers.
Paper, units and breakers
| Europe | North America | |
|---|---|---|
| Paper | A4, A3 | Letter, Tabloid |
| Dimensions | metres | feet and inches |
| Usual breaker ratings | 6, 10, 16, 20, 32 A | 15, 20, 30 A, larger for the big appliances |
| The wiring rules | national rules on the IEC 60364 model, BS 7671 in the UK | the NEC, NFPA 70, adopted state by state |
A page sized for one paper is cut on the other, which is why an export should offer both.
Working with both
Three habits help if your work crosses the line. Keep one plan and change the convention it is shown in, rather than redrawing it; a redrawn plan drifts. Put the names in the legend so the reader has both words where it matters. And state the voltage any load figures assume, so nobody reads a 230 V figure as a 120 V one.
ePlan treats the convention as a property of the person looking, not of the plan. A stored symbol is a device, and the phone or browser decides whether to draw it the IEC way or the US way, with the names to match. The load estimate follows the same choice and says so under the figures, and the export can be at the plan's own shape, on A4, or on US Letter.
Questions
Which convention should I draw in?
The one the people reading the plan were trained on, which is usually the one your regulations and your local drawings use. If the plan will be read on both sides, keep one plan and show it both ways rather than drawing two.
Is a three-way switch the same device as a two-way switch?
Yes. The names count different things, terminals on one side and positions on the other. The wiring, two switches joined by two travellers, is the same.
Can a US plan be printed on A4?
If the export fits the plan to the page, yes, with a little white at the edges. A page laid out for Letter and printed on A4 as it is loses a strip at the bottom or the side.
Why does Europe use 230 V and North America 120 V?
History: the two grids grew up separately and standardised separately. For a plan it only matters in two places, the symbols for the heavy 240 V circuits and the current a given load draws.