two radials into an RCBO

[GBDamo]

Whenever I swap out a board I look to put everything on its own OCPD and leave space for expansion, so there's often more breakers than the original board.

However if I come to a full board, needing a low power radial, I'll always put it to the customer that I can do a "Spur at source" (which some electricians frown on) or I can put in a new board and a dedicated OPCD.

Guess which option they choose.

 

[John-SJW]

You certainly can if you like, but it's not actually required as per other posts as it is legitimately one final circuit with a branch.
There isn't a right answer here - we'd all prefer not to add joints if not required, and we'd prefer not to stick two legs in an RCBO.
I'd probably gravitate to the latter option personally.

It would also give DP isolation to an integrated fridge.

 

[timhoward]

Is this Wylex single module type 2 SPD of any interest:

Wylex NMT2SPD3W/1 Surge Protection Devices

Buy Wylex NMT2SPD3W/1 Surge Protection Devices online at Shop4 Electrical & get FREE Next Day UK Delivery when you order by 2pm & spend £60

www.discount-electrical.co.uk

It is a bus-bar connection too....no breaker needed for it

 

[John-SJW]

I'd make one more comment - perhaps the reason the boiler and the fridge were on separate radial circuits was because they are either (a) somewhat important circuits that could be problematic if tripped, or (b) the loads (at least the boiler or associated valves/pump) are prone to faults. I know most properties don't provide that luxury, pity to take it away.

People like a fridge on their own circuits so if another circuit is at fault the fridge is not taken out,

 

[John-SJW]

Is this Wylex single module type 2 SPD of any interest:

Wylex NMT2SPD3W/1 Surge Protection Devices

Buy Wylex NMT2SPD3W/1 Surge Protection Devices online at Shop4 Electrical & get FREE Next Day UK Delivery when you order by 2pm & spend £60

www.discount-electrical.co.uk

It is a bus-bar connection too....

The Wylex is £70 (taking the mick) to BGs £38. If two radials are joined there is another way available. Not sure if the BG will fit a Wylex.

 

[7029 dave]

People like a fridge on their own circuits so if another circuit is at fault the fridge is not taken out,

But your adding the boiler to this circuit ?, so it is not on its own anymore.

 

[timhoward]

The Wylex is £70 (taking the mick) to BGs £38. If two radials are joined there is another way available. Not sure if the BG will fit a Wylex.

In my experience it's usually the bus bar alignment that is the biggest issue, which as someone said wouldn't apply to an SPD which connects to an MCB.

 

[John-SJW]

By the letter of the regs. , no, but it depends if you're an engineer or a sheep. I have no problem mixing different makes in a full DIN rail CU, as long as they fit properly.
This doesn't connect to the busbar, so no pulling out of shape. The only possible issue is to make sure the front part projects through the front panel enough to meet the IP rating, which it almost certainly will.

The BG can fit onto a Din rail. Not sure if it fits a Wylex busbar, or any busbar.

"Can be fitted on DIN rail directly into the consumer unit."

 

[John-SJW]

But your adding the boiler to this circuit ?, so it is not on its own anymore.

Yep. A compromise.

 

[westward10]

@brianmoooore I agree in this case, and must have missed the previous thread on this.
Out of interest, would your comment mean that 314.4 can never actually be broken if combining radial circuits?

I always follow this, it is two final circuits therefore separate circuit protection.

 

[timhoward]

The BG can fit onto a Din rail. Not sure if it fits a Wylex busbar, or any busbar.

"Can be fitted on DIN rail directly into the consumer unit."

Sorry if we are at cross purposes, or I'm stating the obvious, but the BG has the earth connection at the bottom, and doesn't connect to the bus-bar at all.
With these circuits merged do you have way free or two, as the BG SPD also needs an > B16 MCB .

(The Wylex module does connect to the bus bar and only needs one way total.)

 

[John-SJW]

Sorry if we are at cross purposes, or I'm stating the obvious, but the BG has the earth connection at the bottom, and doesn't connect to the bus-bar at all.
With these circuits merged do you have way free or two, as the BG SPD also needs an > B16 MCB .

(The Wylex module does connect to the bus bar and only needs one way total.)

Thx. Never looked in detail. The Wylex looks the business then. The Wylex's only protection is the main incomer fuse? mmmm

 

[UNG]

People like a fridge on their own circuits so if another circuit is at fault the beer in the fridge is not taken out getting warm,

Fixed that one for you

 

[John-SJW]

Sorry if we are at cross purposes, or I'm stating the obvious, but the BG has the earth connection at the bottom, and doesn't connect to the bus-bar at all.
With these circuits merged do you have way free or two, as the BG SPD also needs an > B16 MCB .

(The Wylex module does connect to the bus bar and only needs one way total.)

Some makers do not recommend an SPD has its own RCBO/MCB, as a dedicated MCB can be left off by mistake. An essential circuit will not be left off, so they recommend it is taken off one of these. They recommend the SPD is taken off an adjacent 32A RCBO/MCB. That may mean three wires into the terminal of an RCBO, which is against the regs as posted here.

 

[westward10]

Some makers do not recommend an SPD has its own RCBO/MCB, as a dedicated MCB can be left off by mistake. An essential circuit will not be left off, so they recommend it is taken off one of these. They recommend the SPD is taken off an adjacent 32A RCBO/MCB. That may mean three wires into the terminal of an RCBO, which is against the regs as posted here.

It is not the fact it may be left off. You need to contact the manufacturer as to whether the spd needs external circuit protection. If you are retro fitting one I suggest you provide external protection otherwise you are interfering with the manufacturers internal configuration which may well go against Regulations.

 

[Dartlec]

The idea is to make a way for an SPD by joining two circuits. The SPD will be a single way unit. The BG SPD looks OK. Can it fit into a Wylex CU?

Type 2 Single Phase SPD (Surge Protection Device) | BG (CUSPDT21-02)

View attachment 86813

Surge Protection Devices sell various ones (Available at some CEF), and the answer I had from them at a trade show a while back is that because it's not on the busbar it is not necessary to 'match' the make of the switchgear for type testing requirements. They do specify a separate MCB though.

Wylex may give a different answer, but SPDs one sounds fair enough to me.

Their (SPD's) technical manager, Katie I think it is, clearly knows her stuff - she's been on some of the E5 podcasts and sits on one of the IET panels I believe - They were one of the first to introduce an SPD before any of the CU makers had one widely available...

 

[brianmoooore]

Doesn't apply to fridges quite so much, because they have a light inside and are opened fairly frequently, but I always try to make sure a freezer is on the same circuit as something else important, such as the wi fi router or TV. That way, if the circuit has tripped out, it will be noticed fairly quickly.
Similarly, I always connect smoke alarms to the same circuit as the most frequently used lights.

 

[brianmoooore]

Out of interest, would your comment mean that 314.4 can never actually be broken if combining radial circuits?

Splitting the ring and leaving both sections connected to the same MCB/RCBO doesn't break 314.4 in itself - it's just two radial circuits from the same source, but the breaker will have to be reduced from 32A to a maximum of 20A, and consideration made as to whether that is likely to be sufficient without experiencing overload. For those reasons, it's often preferable to split into two separate circuits.

 

[nicebutdim]

Doesn't apply to fridges quite so much, because they have a light inside and are opened fairly frequently, but I always try to make sure a freezer is on the same circuit as something else important, such as the wi fi router or TV. That way, if the circuit has tripped out, it will be noticed fairly quickly.
Similarly, I always connect smoke alarms to the same circuit as the most frequently used lights.

When fitting decorative accessories in the kitchen & utility room, I decided to use isolator switches with neons for fridge & freezer. I know those neons will eventually fail, being permanently illuminated, but I like the reassurance of knowing that glow means all is good.

 

[John-SJW]

Splitting the ring and leaving both sections connected to the same MCB/RCBO doesn't break 314.4 in itself -

It clearly does:
314.4 Where an installation comprises more than one final circuit, each final circuit shall be connected to a separate way in a distribution board