"17th Edition CUs" & "Amd3 CUs"

[JohnW2]

Prior to Amd3 of the regs, many suppliers were selling what they described as "17th Edition CUs", which seemed to mean that they had dual RCDs (with or without some 'no RCD' spaces, 'high integrity' ones). Following Amd3, some carried on describing CUs as "17th Edition", but many of them decribed the new metal ones as "Amd 3", or "17th Ed. Amd3" CUs.

Given that I don't think we are expecting any changes in regs relating to CUs, come next week (and/or next year), what do we think they will all be calling the products they sell? "17th Ed" will 'sound old', whilst "Amd 3" will relate to a set of regs which will no longer be 'current', and "18th Ed CU" will not really mean anything in particular!

Kind Regards, John

 

[flameport]

Inevitable there will be '18th edition' efforts for sale.

They will either be identical to the current offerings, or will go down the Wylex route - a company which has recently discovered that Chapter 31 exists and DP RCBOs are the way forward.
https://www.electricpoint.com/media...iles/w/y/wylex_17th-18th_edition_18_pager.pdf
and https://www.wylexreasons.co.uk/

(Most of the contents of Chapter 31 has existed for several decades with little or no change).

 

[John D v2.0]

I think that's more of a marketing questingq than an electrical one! I reckon they will become 18th edition in the marketing but they will be usable for both. If you tested selling the same product with each label, I'm sure you'd sell more of the 18th one, even if the price was a pound more!

 

[ban-all-sheds]

I expect the tester makers will jump on the Edition Bandwagon too.....

 

[JohnW2]

I think that's more of a marketing questingq than an electrical one!

Of course, that's obviously what theh question was about!

I reckon they will become 18th edition in the marketing but they will be usable for both. If you tested selling the same product with each label, I'm sure you'd sell more of the 18th one, even if the price was a pound more!

I'm pretty sure that's all correct. Worse, they would/will probably sell more of the "18th" one, even if the price were appreciably more!

Having said that, both the "17th Ed" and "Amd3" names resulted from changes in regs concerning the CUs, so that naming was not unreasonable. Was this type of naming used by the marketeers in the past - i.e. were their "15th Ed. CUs", "16th Ed. CUs" etc. - and, if so, were those names used even if current regs had not changed requirements for CUs?

Kind Regards, John

 

[ban-all-sheds]

IIRC there were certainly 17th Edition testers, even though nothing had changed wrt testing.

 

[davelx]

Inevitable there will be '18th edition' efforts for sale.

They will either be identical to the current offerings, or will go down the Wylex route - a company which has recently discovered that Chapter 31 exists and DP RCBOs are the way forward.
https://www.electricpoint.com/media...iles/w/y/wylex_17th-18th_edition_18_pager.pdf
and https://www.wylexreasons.co.uk/

(Most of the contents of Chapter 31 has existed for several decades with little or no change).

However, ISTM that draft reg. 531.3.1.201 means that SP RCBOs with unswitched neutral will be compliant in the majority of installations, and in the vast majority of domestic installations.

 

[JohnW2]

However, ISTM that draft reg. 531.3.1.201 means that SP RCBOs with unswitched neutral will be compliant in the majority of installations, and in the vast majority of domestic installations.

Probably now in all installations and circuits ...

... in the April 2018 draft, the first clause of that draft reg ["Except in certain special installations or locations (Part 7),"] has disappeared - with that change, the reg then (and probably 'finally') simply reads "For protection against electric shock, there is no requirement to disconnect / switch the neutral in TT or TN systems."

... which appears to be a blanket statement which encompasses all circuits in all installations.

Kind Regards, John

 

[Notch7]

Out of interest, would a CU with RCBOs on every circuit be a better solution than the current dual option.

From a laymans point of view, nuisance tripping would, I guess, then be restricted to 1 circuit.

 

[ban-all-sheds]

Yes, it would be better.

What do you mean by "the current dual option"?

A CU populated entirely with RCBOs has been an option since RCBOs became available.

 

[EFLImpudence]

Yes, but buying lots of them is expensive - so most people don't have them.

Plus - you cannot tell if a trip was caused by overload or fault.

 

[Notch7]

Yes, it would be better.

What do you mean by "the current dual option"?

A CU populated entirely with RCBOs has been an option since RCBOs became available.

Yes, I could have been more clear, I guess dual boards are the most common current option.

I have heard it mentioned that consumer units are often not tall enough for ease of fitting RCBO's.

 

[flameport]

I have heard it mentioned that consumer units are often not tall enough for ease of fitting RCBO's.

Some may be more difficult to fit - but that's just poor design by the manufacturer.

Not all RCBOs are tall either:


Other manufacturers are available, although in the case of the cheaper ones, they probably all made in the exact same factory anyway.

 

[John D v2.0]

Plus - you cannot tell if a trip was caused by overload or fault.

Interestingly when the CU in the fire flat in grenfell tower was inspected, the occupant had turned off the main switch before leaving, and the MCB and RCD were separate, so they could tell that there had been both an overcurrent and an earth fault during the initial stages of the fire.

 

[JohnW2]

Interestingly when the CU in the fire flat in grenfell tower was inspected, the occupant had turned off the main switch before leaving, and the MCB and RCD were separate, so they could tell that there had been both an overcurrent and an earth fault during the initial stages of the fire.

I suppose that depends upon what you mean by an 'overcurrent'. If a very low impedance L-E fault suddenly appeared, it's not impossible that both MCB and RCD would operate simultaneously - but it would still be the 'earth fault' that had caused the MCB to operate.

Kind Regards, John