Quite so. In circles I moved in, they were often referred to as "Lazy Electricians'Screws" for that very reason. As you say,they have been around for years, and I didn't realise that they were what we were talking about here - because I thought the whole point of them was the antithesis of what has been suggested here - namely that they were designed to be used satisfactorily with either a standard slotted screwdriver or a standard PZ one (and certainly didn't need some 'special screwdriver' - which are the things I'd never heard of().
Maybe, but if that were the case,I would probably question the design of the screw!
Well, not really. Given the starting point, that the screws were already in use, the screwdrivers turn out to be necessary to torque the screws without damage. As you haven't tried them you won't know how solid they feel in use.
Yes, that is what is being said, but if they are properly designed to accommodate a PZ bit, I don't see why such a bit should cause 'damage'.
That's obviously true - so I have no idea as to whether they feel (tome) any more 'solid' than alternatives.
Half of it is.
... but it seems to be being suggested that the half of it designed to accommodate a OPZ bit is not capable of 'working' with a PZ bit without 'damage' resulting - which, as I said, makes me question the design.
Yes, that's the point, it's a bad design.
Quite so. In fact, it sounds as if the screws are "not fit for purpose" - if they are 'designed'/intended to be usable with either PZ or slotted screwdrivers/bits, but 'get damaged' by them!!
.... Well that is a surprise, ever since owning one I've found it's a beautiful fit in every MCB and I believe it's fair to say that it has been used exclusifvely for the purpose. I will add mine is too big to fit in some load sides of RCBOs and a PH2 is used there but not PZ2.I think this may throw a spanner (if not some screwdrivers!) into the works
@333rocky333 has kindly shared with me some correspondence he received from a screwdriver manufacturer and it contains some interesting information about these 'modulo' (PZ/SL) screwdrivers. In essence, it suggests that they have found that such screwdrivers are not suitable for use with most brands of CU devices, and points out that the manufacturers of the devices often advise that only PZ or PH screwdrivers/bts should be used with their device terminal screws.
@333rocky333 would you be happy for me to share ('anonymously') the relevant sections of the e-mail with the forum?
Kind Regards, John
It's my understanding, from other websites, that Wylex have been saying this, in published documents, for years. I also note that Hager show two columns for torquing, one for PZ and one for SL. It makes no sense to me to 1) invent a new screw just because some other vendor is using them and 2) then insist that you can't use a screwdriver that is designed to fit well into this screw head.
I was somewhat surprised, too.
I'll send you the relevant part by PM,but won't post here unless/until rocky says that he's happy with that. No brands were named, but the guy said that only one of the brands he had examined had screws which he considered suitable for a PZ/SL screwdriver. He suggested that one possible explanation is that most device manufacturers may not actually be using PZ/SL-compliant screws and that what they are buying are PZ screws across which a 'slot'has been cut ('for lazy electricians!).
Well I for one always found a ¼" instrument flat blade was the best fit until I got one.
As I understood it, a High Integrity board had two banks with an RCD feeding each, plus a small busbar for 1, 2 or 3 breakers or RCBOs fed off the main switch.
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