Any seen a RCBO like this before?

[Risteard]

Its not obligatory to use single module but all the big manufacturers are supplying their new DB,s with single module so it's inevitable it will become the new norm. I think many sparks (like me ) mistakenly assumed they were DP. It's a backward step in my view

Completely agree. Unfortunately Hager are supplying their domestic DBs with 2 * single mod. RCBOs for the lighting circuits now. I would prefer them to supply with DP busbar and the 2 mod RCBOs. Far superior (and also slightly cheaper).

I've also found the single pole ones unreliable for insulation testing, whereas the 2 mod ones didn't give silly results on this when testing the installation in parallel. I will happily join your crusade for the 2 mod DP RCBOs to be supplied with the DBs.

 

[Raptor0014]

Manufacturers are going double pole RCBO now. Eg I use Fusebox mainly for customers and their Mini single module RCBOs are double pole.

 

[LastManOnline]

I've also found the single pole ones unreliable for insulation testing, whereas the 2 mod ones didn't give silly results on this when testing the installation in parallel.

I,ve had this issue as well. I, m assuming it's to do with the electronics in the rcbo.? Had to carry out testing for an install carried out by a UK company and in order to obtain accurate results had to disconnect the rcbo, s.It was a real time waster.
Two days ago I rang Hagar about their new approach with single mod, s.

 

[nicebutdim]

Two days ago I rang Hagar about their new approach with single mod, s.

Did they disclose anything of interest about future products?

 

[LastManOnline]

Did they disclose anything of interest about future products?

No. Just said the new single mod rcbo does, nt break the neutral. No explanation given as to why not

 

[nicebutdim]

No. Just said the new single mod rcbo does, nt break the neutral. No explanation given as to why not

It's a product they have readily available as it has long been used in the UK. Perhaps they'll develop a 1P+N version if competing products start to increase UK market share or if sparks in IE demand it.

 

[pc1966]

I wonder if this is a "UK/ROI centric" move by Hager, based on typically TN supply, but they still do DP RCBO for EU as typically TT supply?

It really is disappointing that practically nobody does a 1 module double busbar system to avoid the flying leads, and only a few do 1-module neutral-switching RCBO (though I suspect that Fusebox/Wylex/Crabtree might be a significant portion of UK domestic RCBO installations and they do SP+N switching).

 

[Jim_e_Jib]

I wonder if this is a "UK/ROI centric" move by Hager, based on typically TN supply, but they still do DP RCBO for EU as typically TT supply?

It really is disappointing that practically nobody does a 1 module double busbar system to avoid the flying leads, and only a few do 1-module neutral-switching RCBO (though I suspect that Fusebox/Wylex/Crabtree might be a significant portion of UK domestic RCBO installations and they do SP+N switching).

Do SBS have a patent, or some other rights, over the dual busbar system that make it harder for others to implement in the UK?

 

[pc1966]

Do SBS have a patent, or some other rights, over the dual busbar system that make it harder for others to implement in the UK?

I have no idea. I always assumed it was simply that folks wanted RCBO to fit existing CU and nobody actually started from the sensible point of L & N busbars.

Same issues for TPN boards of course, though I have been told that Schneider do a neutral bus but don't know how that works in practice as never seen/played with one.

 

[LastManOnline]

I wonder if this is a "UK/ROI centric" move by Hager, based on typically TN supply, but they still do DP RCBO for EU as typically TT supply?

I posted a thread here locally 2 days ago asking Irish sparks how they felt about the new single module rcbo,s that don t break the neutral. The response is disbelief.It would appear the both regulators and rcbo manufacturers have decided to not publicise this developement.Lets see how things develope

 

[pc1966]

I posted a thread here locally 2 days ago asking Irish sparks how they felt about the new single module rcbo,s that don t break the neutral. The response is disbelief.It would appear the both regulators and rcbo manufacturers have decided to not publicise this developement.Lets see how things develope

I would have to check, but I think the UK regs for TT require DP switching.

Now if you have a 100mA DP RCCB as incomer then some 30mA RCBO for shock protection you get most of that, but personally I feel it should be DP anyway, not just for the risk of a high-N voltage under fault conditions, but also so you get the desired selectivity between RCBO and any up-front RCCB.

 

[westward10]

For ADS on a TT system there is no requirement to switch the neutral, for isolation however all live conductors must be switched.

 

[pc1966]

For ADS on a TT system there is no requirement to switch the neutral, for isolation however all live conductors must be switched.

Thanks for that!

I might have been thinking of the caravan case which (again from flaky memory) have to be DP.

 

[nicebutdim]

I posted a thread here locally 2 days ago asking Irish sparks how they felt about the new single module rcbo,s that don t break the neutral. The response is disbelief.It would appear the both regulators and rcbo manufacturers have decided to not publicise this developement.Lets see how things develope

I hope you highlighted to them the manufacturers who provide single module options for isolating both conductors. Hagar seem to be a very popular brand, both in the UK and IE, but more than once I've found myself looking at their products and asking how this came to be the case.

I note that SBS have since been mentioned in this thread. They're another brand offering 1P+N RCBOs and their dual busbar means no neutral flylead.

 

[Peter - Retired Engineer]

One issue is the lack of discrimination between this upfront RCBO and downstream RCBOs in the new board. Is there a reason why a switchfuse wouldn't provide sufficient protection for the armoured cable?

Will the workshop have its own DB or is everything running directly off that one circuit? If it does have its own DB, can you tell more about it?

Hi, A bit of a delay in replying: Our electric 1/2 AGA 60, arrived a day early!
I agree with you that I'm not sure how any discrimination between the inline RCBO's will work. The one I have fitted today (As in the original post) is a 'C' curve, so hopefully will not cause any nuisance trips and the electric gates and workshop 'B' curve RCBO's will work on their own... I have just connected the EV up to the Zappi (protected just by a 32A MCB) - that's working fine.
As to a 'switchfuse', that would have been the simplest idea and bad planning on my part. I had fitted a 65A Isolation external switch, (just outside of the meter cabinet), but forgot about any overload protection. So I'm hoping everything is covered now.
My workshop when built (Builders did not turn up today), I will add another consumer unit inside with AFDD (18th Amendment 2 - wood construction), a lighting circuit and 2 radial circuits for the sockets.
Thanks for your professional comments.

 

[nicebutdim]

The issue of discrimination will not be affected by the different trip curves, as they relate to overload protection, and it will be pot luck as to which trips in the even of any fault involving imbalance between line and neutral. As the garage board is also to be populated with RCBOs, this would add a third possibility in the event of such a trip - not an ideal situation from the perspective of design or practicality.

 

[Peter - Retired Engineer]

The issue of discrimination will not be affected by the different trip curves, as they relate to overload protection, and it will be pot luck as to which trips in the even of any fault involving imbalance between line and neutral. As the garage board is also to be populated with RCBOs, this would add a third possibility in the event of such a trip - not an ideal situation from the perspective of design or practicality.

Thanks, I'll have to think about it before progressing any further. Will probably be a month before the workshop is built and ready for electrics... It might be easier to swap the first RCBO for a switchfuse...

 

[DPG]

Thanks, I'll have to think about it before progressing any further. Will probably be a month before the workshop is built and ready for electrics... It might be easier to swap the first RCBO for a switchfuse...

That sounds like a better idea to me.

Out of interest, what make of AFDD are you going for, and how much are they each?

 

[Raptor0014]

That sounds like a better idea to me.

Out of interest, what make of AFDD are you going for, and how much are they each?

Cheapest ones I’ve found I can get so far are Fusebox at £106.92 inc VAT

Had a customer last week asking for a quote for a full AFDD board which had 15 circuits.

Soon changed his mind when I said that’s £1600 in circuit protection before we even start with the rest of the materials, labour, testing, certification etc.

 

[pc1966]

Thanks, I'll have to think about it before progressing any further. Will probably be a month before the workshop is built and ready for electrics... It might be easier to swap the first RCBO for a switchfuse...

If you want reasonable selectivity that is the way to go, at least where the sub-main is in SWA so has no need for "30mA additional protection" itself.

Generally I would push the sub-main's supply fuse as high as the sub-main end of cable Zs will allow, but ideally still two steps down from the DNO fuse so it has selectivity with that. (e.g. DNO = 100A then 63A, or DNO = 80A then 50A should have total selectivity with it).

Your high-current selectivity between fuse and RCBO will depend on type and make, etc. For Hager their commercial distribution catalogue has handy tables of selectivity between BS88 fuse & MCB, MCB & MCB, etc. As an exercise, for 50A fuse and Hager 32A B-curve RCBO the selectivity limit is 1.1kA, so faults in the garage below that current ought only to trip the RCBO.

Of course, faults off a 13A fused plug or FCU will be totally selective with any supply fuse of 32A or above.

If you plan this as a workshop then supply selectivity is a bit more of a concern as a fault taking out the lights as well is a real danger. You might also want to put in some emergency lighting just in case (even for mains supply failure) so you are not plunged in to darkness with tools still spinning, etc. You can buy baton-style LED strip lights with battery back-up built in, that is a simple options.