Terminology
Technical terminology used for electrical installations can be a cause of ambiguity, in certain situations. This is due to regional and country-specific differences or because certain terms might have changed over time.
This page clarifies the terminology used on this site and some of the reasons for their specific usage.
European and American terms
The terminology used in North America and Europe can often differ considerably. This site tends to use European terms, however American terms are also occasionally present, for clarity, depending on the specific context.
This table compares European technical terms, alongside their American counterparts:
| European word | American word |
|---|---|
| Line wire | Hot wire |
| Earth, Earthing | Ground, Grounding |
| Socket with shutters | Tamper-resistant (TR) outlet |
| RCD, RCCB, (antiquated) ELCB | GFCI |
| RCBO | GFCI breaker |
| AFDD | AFCI |
Moreover, some terms exist that are only specific to a certain geographical area. For example, mentions of a "bonding screw" or "bonding the neutral to ground" are specifically referring to the North American implementation of what in Europe would be called a TN-C-S earthing system. There isn't a direct European equivalent, as in supplies with this style of earthing the split between the incoming combined earth and neutral is handled by the supplier, not the consumer.
The name given to the combined earth and neutral conductors also varies; in North American practice this is still referred to as, simply, the neutral. In Europe this is generally called PEN (Protective Earth and Neutral) or, in the UK, CNE (Combined Neutral and Earth). It may also be referred to as PME (Protective Multiple Earthing, British) or MEN (Multiple Earthed Neutral, Australian), though these terms are technically referring to the practice of earthing the PEN at multiple points, rather than being a name for the conductor itself.
Light switch terminology
Even the names used to refer to different types of light switches are different between American and British English. In general, AmE terms seem to refer to the number of terminals on the switch (so, of course, a minimum of two) while the BrE terms are based on its function.
| BrE word: | One-way switch | Two-way switch | Intermediate switch |
|---|---|---|---|
| AmE word: | Two-way switch | Three-way switch | Four-way switch |
| Meaning: | Switch used for controlling a light from one position | Switches used together to control a light from two different points | Switch used together with the previous type of switch to control a light from more than two points |
Voltage ratings
On the various pages on this site, different but similar voltages may be used, depending on the context; for example, 100, 110, 120, 125 and 127V, or 220, 230, 240 and 250V.
While in practice the difference between these voltages is minimal (supply voltages tend to fluctuate), it's generally preferrable to use the correct one when talking, depending on what's being described. Below is a list of voltages between 200 and 250V and what they generally refer to.
- 200V: Voltage between phases found on Japanese split-phase systems. The line-neutral voltage is 100V.
- 208V: Voltage between phases used on some American three-phase systems. The line-neutral voltage is 120V. Often found on supplies feeding apartments.
- 220V: Old continental European supply voltage and still officially used in some parts of the world. I'll generally use this when talking about electrical history, older items or items made in countries that still officially use this voltage.
- 230V: Current standardised voltage used in Europe and Australia (a middle ground between 220V and 240V). I'll generally use this when talking about modern European and Australian electrics.
- 240V: This voltage is or was mostly used in English-speaking countries - most notably, the North American split phase voltage is 240V (between phases). 240V between line and neutral was also the voltage formerly used by the UK, NZ and Australia.
- 250V: Most common rating for devices meant to be used on 220-240V mains. For example, European sockets are rated at 250V, even though the line voltage is supposed to be 230V. Seeing devices with a slightly higher voltage rating than the mains one is quite common, as it adds a margin of tolerance.