Conductors should be of an appropriate size for the application, and should pass through openings with no sharp edges with sufficient clearance to prevent fraying or damage. If they are accessible to the user of the product, they must be tested to withstand a certain amount of “strain” (for more on strain relief, see below). Finally you can never cross low voltage and high voltage conductors unless the low voltage wiring is rated for the higher voltage. For example, a wire carrying 12 volts may be in contact with a wire carrying 120 volts so long as it is rated for 120 volts itself.
The UK has left the EU, and the transition period comes to an end on the 31st December 2020. For information on what you'll need to do from 1 January 2021, read:
Placing manufactured goods on the market in Great Britain from 1 January 2021
Placing manufactured goods on the market in Northern Ireland from 1 January 2021
Placing manufactured goods on the EU market from 1 January 2021
Using the UKCA mark from 1 January 2021
Conformity assessment bodies: change of status from 1 January 2021
Our 25 years of experience in testing has shown us that 9-out-of-10 products fail the first time they undergo testing. We can help you avoid many testing problems, and find solutions for whatever noncompliance issues might arise.