Electricity

Alternating Current (AC)

Oh, so NOT any globally usable standard…
- Different voltages in different markets (e.g. 120 VAC, 220 VAC, 240 VAC; single-phase, then there’s also 3-phase…)
- Different frequencies – 50 Hz or 60 Hz
- Different plugs/connectors
  - worldstandards.eu/electricity/plugs-and-sockets/
- worldstandards.eu/electricity/plug-voltage-by-country/
- en.wikipedia.org/wiki/Mains_electricity_by_country
- en.wikipedia.org/wiki/AC_power_plugs_and_sockets
- Examples:
  - US (and CA): 120 VAC, 60 Hz nominal (Mexico: 127 VAC, 60 Hz nominal, devices can be used across North Americas)
    - Plugs ‘A’, ‘B
  - EU: 230 VAC, 50 Hz, nominal
    - Plugs ‘C’, ‘E’ – e.g. France
    - Plugs ‘C’, ‘F’ – e.g. Germany, Finland, Spain, Sweden, …
    - (Plug ‘C’ is called the “Europlug”)
  - UK: 230 VAC, 50 Hz, nominal
    - Plug ‘G’ (BS 1363) (UK, Ireland, Malaysia, Malta, Singapore, Bahrain, Sri Lanka, and Saudi Arabia)
Utilities – from the grid, your regular electricity provider
Circuits, Breakers
Generators – /energy/generators
Transfer switches
- Automatic Transfer Switch (ATS)
- Manual Transfer Switch (MTS)
AC-to-DC converters, AC-DC power supplies, a.k.a. Rectifiers in more professional applications (e.g. 110 VAC to 5 VDC), chargers (AC to some DC plus smartness specifically for different chemistries, very important to pro-longing lifetime of batteries, as well as avoiding runaway conditions and even explosions)

Direct Current (DC)

Batteries – /energy/batteries
Cables and Connectors
- Barrel connectors, a.k.a. Coaxial connectors (many sized, no formal standards regarding what voltage with which size, and most are center-positive though there are exceptions, like electrical musical instruments- be careful reusing any power adapters if you’re into music)
  - en.wikipedia.org/wiki/Coaxial_power_connector
  - some sizes include
    - 2.35 x 0.75 mm
    - 3.0 x 1.0 mm
    - 3.5 x 1.35 mm
    - 4.0 x 1.7 mm
    - 4.8 x 1.7 mm
    - 5.5 x 2.1 mm – see also note below on 5.5 x 2.1 and 5.5 x 2.5
    - 5.5 x 2.5 mm – -“-
  - and some voltages include
    - 3V
    - 5V
    - 6V
    - 7.5 V
    - 9 V
    - 12 V
    - 13.5 V
    - 15 V
    - 24 V
    - 48 V
  - (Example of AC-DC adapter amazon.com/Belker-Universal-Adapter-Household-Electronics/dp/B07J6RC43S)
- Cigarette lighter receptacle, Automobile auxiliary power outlet
  - en.wikipedia.org/wiki/Automobile_auxiliary_power_outlet
  - having one of these as a loose item on a cable with clamps – that can be easily connected to a battery – and/or some barrel connector – for connecting to a AC-DC power source – can come handy when you least expect… (like when you gather cables for charging phones from the car or boat where you used the cigarette lighter jack)
USB (5 VDC) – – one of relatively few global standards (same connectors and voltage around the whole world), but… there are ‘a few’ connectors to juggle
- A
- B
- C
- Mini
- Micro
Converters, DC-to-DC (e.g. 12 V to 5 V)
Inverters, DC-to-AC (e.g. 12 VDC to 120 VAC)
Voltages
- 5VDC, USB – one of relatively few global standards (same connectors and voltage around the whole world), but… there are ‘a few’ connectors to juggle
- 12VDC, automotive batteries around the world, to the larger degree
- 48VDC, (e.g.) Power over Ethernet (PoE), one other of relatively few global standards (same connectors and voltage around the whole world)

5.5 x 2.1 and 5.5 x 2.5 Barrels

As example, may apply also on other similar-size barrel connectors. Points are be very careful of both physical sizes (1), voltages (2), as well as polarity (3). Most common polarity IS positive center but never take for granted.

NOTE: markings on connectors can be quite absent and it can sometime be easy to mistake 2.1 mm with 2.5 mm flavors.

From Male / To Female	… a 5.5 x 2.1 Female	… a 5.5 x 2.5 Female
5.5 x 2.1 mm Male, into ….	Yes, of course	Nope, can’t fit into
5.5 x 2.5 mm Male, into …	Yeah… can get in but will wiggle, can even be very loose, easily fall apart	Yes, of course