I want to sell an electrical product with an earthed, metallic enclosure for commercial use in Europe.

The wiring inside the product is pretty tight. Are there any laws that prevent me from having an earthed mains circuit in 600V insulated wire touching a low-voltage, earthed secondary circuit in 300V insulated wire?

If the 600V insulation fails (single fault) then the secondary is still protected with 300V insulation, and vice versa. Correct?

  • \$\begingroup\$ without a schematics and photo is hard to understand. \$\endgroup\$ Commented Mar 5, 2019 at 11:48
  • \$\begingroup\$ Not an answer but- this is not allowed by UL, as I understand it. The lower voltage wire has to be insulated (or sleeved) to withstand the highest voltage in the enclosure. At least that is what we had to do on a product. \$\endgroup\$ Commented Mar 5, 2019 at 11:56
  • \$\begingroup\$ It is -- universal mains doesn't go above 300V in normal operation. \$\endgroup\$ Commented Mar 5, 2019 at 11:58
  • 1
    \$\begingroup\$ @Jack the Lad If you're in Europe, in some areas you could regularly have 370 Vpp on the sinewave, and the supply might still be within its tolerances. \$\endgroup\$
    – AndrejaKo
    Commented Mar 5, 2019 at 12:24
  • \$\begingroup\$ So every wire in mains-powered equipment has to be insulated to >370V? Seems a bit over the top. It would be hell trying to solder 600V wires to a USB port. Do you know the number of the standard? \$\endgroup\$ Commented Mar 5, 2019 at 12:29

2 Answers 2


In Europe the IEC and CE standard are applicable.

There are a bunch of IEC norms, but if you want to sell your product to Europe you probably will have to go through a third party certification body like TUV whom they could provide you better guidance over the vast amount of norms.

As per your question, I would say it depends what you mean by "touching", if there is a risk of abrasion. You could sleeve the wire.

For sure you would need the insulation of that particular wire to be rated for the voltage.


The law you must obey are the (applicable) directives.
To prove you comply to the directives, you can (but don't have to) use standards. You are allowed to prove otherswise, but using standards is the best/safest.

Do read Is RoHS and EMC compliance enough for a 24V industrial sensor to carry CE Mark? for applicable links.


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