AC voltage levels:
0.316V The most common nominal level for consumer audio equipment is -10 dBV, 0.316 volts root mean square (VRMS).
0.7746V The reference voltage for the decibel unloaded (0 dBu) is the voltage required to produce 1 mW of power across a 600 ohms load (approximately 0.7746 VRMS)
1V The reference voltage for the decibel volt (0 dBV) is 1 VRMS, which is the voltage required to produce 1 milliwatt of power across a 1 kilo-ohm load
1.228V The most common nominal level for professional equipment is 4 dBu. A signal at +4 dBu is equivalent to a sine wave signal with a peak amplitude of approximately 1.737 volts,or any general signal at approximately 1.228 VRMS.
12V A low voltage lighting system usually operates on 12 or 24 volts.
24V A low voltage lighting system usually operates on 12 or 24 volts.
24V Used for controlling relay coils in some automation and control systems.
50V Extra-low voltage high limit is 50V AC

50V Low Voltage Directive is effective for voltages in range 50 – 1000 volts a.c. or between 75 and 1500V DC
75V Typical telephone line ring voltage is 75 V a.c.(20 or 25 Hz), it could be between 40 and 150 Volts (15-68 Hz)
100V Mains voltage in Japan. Reference voltage level used on electrical power stations measurements (100V = nominal high voltage on line being measured)
110V Mains power in USA, the voltage you expect to get from mains outlet
115V Mains power in USA, the voltage you expect to get from mains outlet
120V Mains power in USA, the output voltage on the distribution transformer
200V If the voltage is less than 200 V, then the human skin is the main contributor to the impedance of the body in the case of a macroshock—the passing of current between two contact points on the skin.
208V The voltage you expect to get between two phases in USA in case our apartment
gets two phase wires from three phase transformer (208/120V)
220V Old European nominal voltage, harmonized to 230V
230V Electricity supplies within the European Union are now nominally 230 V ± 6% at 50 Hz
240V the voltage you expect get between two hots in USA on your hous
240V Old nominal mails voltage used in UK, harmonized to 230V
240V the voltage you get between two hots in USA on the distribution transformer
277V Voltage between phase and neutral on 277/480V three phase system, used in USA for example lighting loads on big buildings
400V Voltage between phases on 220/400V three phase system (old European system)
415V Voltage between phases on 230/415V three system (modern European system)
450V If the voltage is above 450–600 V, then dielectric breakdown of the skin occurs
480V Voltage between phases in USA in commonly used 3 phase distribution
600V Three phase power voltage
690V Three phase power voltage used in industry for larger electrical motors (Europe)

1000V Isolation test voltage for 130V rated working voltage basic isolation (IEC950)
1000V Low Voltage Directive is effective for voltages in range 50 – 1000 volts a.c. or between 75 and 1500 volts d.c
1000V There phase power voltage used on 1 kV power distribution (in use in Finland)
1350V Basic insulation of 1350V rms is needed for test-and-measurement instruments rated at 250V (IEC 61010-1)
1500V Basic insulation of 1500V rms is needed for information-technology products rated at 250V (IEC 60950-1)
1500V Isolation test voltage for 230V rated working voltage (IEC950) (basic isolation)
2100V Isolation test rating for reinforced isolation for 130V rated devices
2300V Use 2300V rms or 3250V dc test voltage for dielectric-withstand test for double insulation
7.2kV Common distribution voltage in USA
10kV Common distribution voltage in Finland
11kV Common distribution voltage in UK, New Zealand and Australia
12.47kV Common distribution voltage in USA
20kV Common distribution voltage in Finland
25kV Electrical trains use 25kV 50Hz power in Finland
33kV Common distribution voltage in UK, New Zealand and Australia
34.5kV Common distribution voltage in USA
110kV Commonly used voltage level on long distance electrical transportation lines
220kV Commonly used voltage level on long distance electrical transportation lines
400kV Commonly used voltage level on long distance electrical transportation lines