The Elf wrote:Several of my keyboards have their nasty little external PSUs inside their cases, with a nice, friendly IEC connector added.
The Elf and I have covered this ground before, but for the benefit of others new to this approach, enclosing the PSU and retrofitting a new mains inlet is not quite as trivial as it might appear, and should not be attempted without a thorough understanding of the issues involved, and the appropriate electrical and mechanical competencies.
Most (but not all) products with line-lump PSUs are Class 2 devices, meaning they do not have a direct connection to the mains safety earth, and the PSU would typically have a two-pin C8 (fig-8) mains inlet. However, assuming the PSU can be housed inside the product somewhere, retrofitting a three-pin C14 IEC inlet may cause some problems.
The relevant regulations state that a three-pin C14 inlet implies a Class 1 device, meaning its exposed metalwork is grounded via the mains safety earth. But if the modified device is actually Class 2 (Double Insulated) there may not be any exposed metalwork, or such metal as does exist may not be tied back to the equipment's ground. And consequently, the modified unit would probably fail a PAT test... Which could be a bit upsetting if you're not allowed to plug your customised keyboard In on stage!
Or... If the mains safety earth is connected internally as part of the modification to the instrument's ground, you could end up with ground-loop issues that didn't exist with the factory-fresh instrument.
Of course, the obvious, simple, and regulation-correct solution would be to fit a two-pin C8 (fig-8) inlet on the modified Class 2 device, and a three-pin C14 on a Class 1 device... But I know the Elf prioritises the convenience of needing only one type of mains lead over slavishly following the relevant regulations.... ;-)
Just to be clear, there's nothing intrinsically electrically unsafe about retrofitting a class 2 device with a C14 inlet -- providing it is done competently, of course. The earth germinal is just left unconnected. However, it is definitely electrically unsafe to retrofit a C8 inlet to a Class 1 device since the required safety earth would have no way of being connected!