Professional install flagged by electrical inspection

[flameport]

It's vanishingly unlikely that an RCD will not be "needed at all"

In a domestic property, yes.


however this is

a charity building i know had A/C professionally installed in 2022,

 

[SimonH2]

Can you point me at any papers which show that it is possible to make LED drivers, SMPSUs, variable-speed motors, induction hobs, EV chargers, solar inverters etc which do not produce DC or high frequency residual current components?

I c.b.a. to go looking for papers, but :
• it's actually fairly easy to avoid DC currents - unless you do stupid things.
• the rest is down to sensible circuit design - design techniques to reduce production of harmonics, and filtering to further reduce their passing back into the supply.

In the past I have a hand in some design work, so it's not something I'm unfamiliar with.

With a past work hat on I was involved with power systems for a military application, and one of the things we were testing for was how carp some commercial off the shelf items were (and some were spectacularly bad), with one variable speed drive causing so much noise it needed a custom filter in front of it. I strongly suspect (but we didn't look into that as it was outside of our remit) that it didn't meet civilian standards foor mains powered equipment it was so bad. But we also had other equipment with similar variable speed arrangements that didn't have that problem - because they were better designed in the first place. That was on some high power industrial equipment - on the scale of domestic equipment, the design issues to "do it right" are almost trivial.
It can be done, if you care enough to actually consider it worth doing - rather than design the cheapest piece of s**t you can and make any problems an S.E.P. (someone else's problem.) But then, too many companies outsource design to the cheapest quote with the highest rated factor of "design goodness" being minimal component and manufacturing costs.

 

[ebee]

Hmm interesting