If L.E.D. lights rated at 220 Volts are supplied at 240 Volts will they perhaps flash on and off?

LED lights for both Germany and the UK should be rated 230 V.

Table 1 of BS EN 60038 CENELEC Standard Voltages. Manufacturers are pointed in Clause 4.1 of the standard, to the fact that the supply voltage (at the origin of the consumer's installation) will have a variation within ± 10 % (in the UK, according to ESQCR, it's + 10 %, - 6 %), and that there will be a further voltage drop within the consumer's installation according to HD 60364-5-52 (Chapter 52 of BS 7671 in the UK).

In fact, 220 V is not an IEC standard voltage either (IEC 60038) ... for 50 Hz supplies, it's still 230 V, which means that the lights are not produced for a country that follows IEC standards either.

So I would either not install them, or query the voltage with the manufacturer.

The standard voltages have been that way for some very very long time.

LED lights for both Germany and the UK should be rated 230 V.

Table 1 of BS EN 60038 CENELEC Standard Voltages. Manufacturers are pointed in Clause 4.1 of the standard, to the fact that the supply voltage (at the origin of the consumer's installation) will have a variation within ± 10 % (in the UK, according to ESQCR, it's + 10 %, - 6 %), and that there will be a further voltage drop within the consumer's installation according to HD 60364-5-52 (Chapter 52 of BS 7671 in the UK).

In fact, 220 V is not an IEC standard voltage either (IEC 60038) ... for 50 Hz supplies, it's still 230 V, which means that the lights are not produced for a country that follows IEC standards either.

So I would either not install them, or query the voltage with the manufacturer.

The standard voltages have been that way for some very very long time.

It may not be entirely coincidental that the mains voltage in China is 220V.

It may not be entirely coincidental that the mains voltage in China is 220V.

Officially 220V, and 380V phase to phase  - not always in practice - but if out of bounds,  usually on the low side rather than high.  I have heard it suggested that when a lot of this was being set-up, there was a desire to be compatible with the Soviet bloc  in terms of voltage and wiring practice, though this never extended to the sockets, which are more like the type you see in Oz or Nz.

Mike