Why do we do it the way we do in the UK?

[Mikegh]

You can get DP RCBOs in single width, like the compact Wylex, Crabtree, and fusebox RCBOs so they take no more space then traditional UK style MCBs.

I really prefer DP ones for various reasons:

• They isolate both L & N so you can IR test the circuit without having to unscrew anything
• If you have a TT style arrangement with an up-front delay RCD the you don't trip that on a N-E fault downstream (as N is isolated)
• If you are really unfortunate and have reversed polarity, you still get some hope of a fault being interrupted (but you really don't want to test that out as the I2t of the relatively slow RCD opening action will be horrendous)

Can you get a L+N busbar for the single width ?

 

[Mike Johnson]

You mean the MCB side of it ?

It'll be just on the L pole

?

 

[loz2754]

Can you get a L+N busbar for the single width ?

Yes. Crabtree and SBS make such a consumer unit.

 

[Mikegh]

?

I must have misunderstood your post then

 

[Simon47]

You mean the MCB side of it ?
It'll be just on the L pole

?

It's one of those "you need to check" things. I expect the some of the two module types will sense (MCB function) on both poles, and some of the single module types don't even switch the neutral.
Some of the single module types sense on the L pole only (for the MCB function) but switch both poles. Obviously for the RCD function they sense on both poles.

 

[LastManOnline]

Its all DP 2-mod rcbos here

The DP 2 mod rcbo, s with L and N busbar fed from underneath is undoubtedly one of the best designed and user friendly DB, s that's ever hit the market. It really should be the "gold standard". However, after 25 years of using them I, m sad to say, there appears to be a change on the way. (over here in ROI). Have you seen the latest Hagar designed DB based on the new 2021 regs?

 

[Mikegh]

The DP 2 mod rcbo, s with L and N busbar fed from underneath is undoubtedly one of the best designed and user friendly DB, s that's ever hit the market. It really should be the "gold standard". However, after 25 years of using them I, m sad to say, there appears to be a change on the way. (over here in ROI). Have you seen the latest Hagar designed DB based on the new 2021 regs?

No, I'm familiar with the changes to DBs in the new rules here, but haven't seen the Hager board

 

[LastManOnline]

No, I'm familiar with the changes to DBs in the new rules here, but haven't seen the Hager board

 

[Mikegh]

The DP 2 mod rcbo, s with L and N busbar fed from underneath is undoubtedly one of the best designed and user friendly DB, s that's ever hit the market. It really should be the "gold standard". However, after 25 years of using them I, m sad to say, there appears to be a change on the way. (over here in ROI). Have you seen the latest Hagar designed DB based on the new 2021 regs?

What's actually in the Hager board

We're very similar to the UK now non-, combustible boards, arc fault and surge protection

Heading towards all rcbo although I think it's only a recommendation

They can't seem to think straight on bathroom lighting ,went ott with emergency lighting and rcbos and now they're allowing it on a shared rcd if I'm not mistaken

 

[LastManOnline]

I install this tomorrow. First rewire under new regs. To my great surprise the single module rcbo and the "dreaded flylead" has invaded our shores. Our beloved 2 pole rcbo and L +N busbar is being sacrificed for space in preparation for rcbo populated DB, s.

 

[Mikegh]

Thanks I forgot the DP main isolation about time there , more harmonization with the UK

Surge protection

Dual RCDs is it , so that would be base spec in comparison to an rcbo board. ?

Didnt take a proper look yet but if they're gone from lighting mcbs to lighting on shared RCDs that would be a backward step

 

[Mikegh]

I install this tomorrow. First rewire under new regs. To my great surprise the single module rcbo and the "dreaded flylead" has invaded our shores. Our beloved 2 pole rcbo and L +N busbar is being sacrificed for space in preparation for rcbo populated DB, s.

Oops sorry I see the single mod 6amp lighting rcbos there ,proper order

 

[Mikegh]

And that's a shower rcbo too

I do shoot from the hip

Nice board

Good to see the DP main isolation and lighting rcbo kept separate from power , if its even advisable for domestic lighting in the first place which I have my doubts

 

[nicebutdim]

I install this tomorrow. First rewire under new regs. To my great surprise the single module rcbo and the "dreaded flylead" has invaded our shores. Our beloved 2 pole rcbo and L +N busbar is being sacrificed for space in preparation for rcbo populated DB, s.

Hate to break this to you, but those shores were breached some time back - now we're just slipping them over the border ?

On a more serious note, if single module RCBOs are going to become more commom in IE, it might be an idea to look at options that don't require a flylead - at least until such times as Hagar catch up.

 

[pc1966]

Thanks I forgot the DP main isolation about time there , more harmonization with the UK

What is very different though is the use of a 63A B-curve MCB as input isolator.

Certainly I think isolation should always be all-pole (though for TPN that is not so common and ideally then you want a mate first / break last on N) and I was surprised that ROI did not do so in the past.

The use of the MCB to me is kind of mixed, I can see it is a good idea to limit each CU's total current without pushing the DNO fuse in to that job (I presume ROI still has the equivalent of a fuse as ultimate limiter?) but it also seems a bad idea on selectivity as many high current faults will take out both the faulty circuit and the whole damned supply!

63A B-curve instant trip is 189-315A, though looking at the Hager tables it would be selective with a 20A B-curve for socket radial to around 700A. That is still less than often seen for PSSC on sockets here (my experience mostly the RFC, maybe easier at ends of 20A radial though?).

 

[LastManOnline]

What is very different though is the use of a 63A B-curve MCB as input isolator.

Certainly I think isolation should always be all-pole (though for TPN that is not so common and ideally then you want a mate first / break last on N) and I was surprised that ROI did not do so in the past.

The use of the MCB to me is kind of mixed, I can see it is a good idea to limit each CU's total current without pushing the DNO fuse in to that job (I presume ROI still has the equivalent of a fuse as ultimate limiter?) but it also seems a bad idea on selectivity as many high current faults will take out both the faulty circuit and the whole damned supply!

63A B-curve instant trip is 189-315A, though looking at the Hager tables it would be selective with a 20A B-curve for socket radial to around 700A. That is still less than often seen for PSSC on sockets here (my experience mostly the RFC, maybe easier at ends of 20A radial though?).

Yes. There has always been a switch fuse between the DNO and the customers DB. A short circuit on the cooker or shower circuit could potentially take the 63 amp mcb out but to date I have not experienced it. All installations are entitled to install a 63 amp "C" curve if the Fli allows for it which most will.
The DB on the picture is not available off the shelf yet in most wholesalers and I was, nt given a choice. I had to order direct from Hagar as I have a job to finish. Still struggling to get the new LZSH in all the necessary sizes due to the delays caused by covid

 

[Simon47]

Insides of an SBS board. The neutral bar tabs are visible, the live bar tabs are under a plastic cover. A bit sparse, but I wanted plenty of room for future expansion.

 

[pc1966]

Insides of an SBS board. The neutral bar tabs are visible, the live bar tabs are under a plastic cover. A bit sparse, but I wanted plenty of room for future expansion.

That looks really neat!

Are the SBS RBCOs dual-pole switching?

 

[Timbo]

That looks really neat!

Are the SBS RBCOs dual-pole switching?

Yes. Used a few now. Had an email recently saying they now do a DP MCB to fit the dual busbar system.
Also their SPD's are very reasonable price.

 

[Timbo]

Deleted duplicate post.