RCD RATING VS. SERVICE FUSE RATING

[spud1]

Hi chaps

A Wholesaler told me me this week that the RCDs in the new '18th' split load boards have to be rated at 100a because the 100a service fuse is only means of upstream overcurrent protection. But I was once told that service fuses, although marked as 100A on the cutout label are actually only actually 80amp?

Any thoughts guys?

 

[Ian1981]

Just had a wholesaler email. Hager have responded to their interpretation of this by releasing dual RCD boards with 100A RCCBs.

As the regulation requires that manufacturers instructions are to be taken into account regarding overload it stands to reason that at least with Hager , they are requiring overload protection of their rccb’s in their consumer units

 

[Ian1981]

 

[Ian1981]

 

[Deleted member 26818]

As the regulation requires that manufacturers instructions are to be taken into account regarding overload it stands to reason that at least with Hager , they are requiring overload protection of their rccb’s in their consumer units

No, this does not require the instructions to be taken account of.
This requires the instructions to be complied with.

 

[Ian1981]

No, this does not require the instructions to be taken account of.
This requires the instructions to be complied with.

Yes as in overload shall be provided

 

[Deleted member 26818]

Please note:
Taking account of Manufacture’s instructions is not the same as following, complying with or adhering to, Manufacturer’s instructions.

 

[westward10]

Can we continue this debate without resorting to pointless posts. It is an interesting point and I thought you two were on each others Christmas card lists these days

 

[happysteve]

Hager now are supplying their dual rcd boards with 2 x 100amp 30mA rccb’s which are now type A with or with out an SPD

Yep, and the prices have gone up by a staggering 64% (example used is old VML710CU to new VML910CU). I don't fit many of these (mostly all-RCBO boards) but now the price differential between a high integrity, and an all-RCBO board makes it less worth while now.

I'm impressed at the minimal price difference between boards with and without SPDs, though; e.g. difference between VML114 (14 way, main 100A main switch) and VML112SPD (12 way, 100A main switch with Type 2 SPD) is a fairly reasonable £74.95+VAT (and you also save the cost of 2 blanks ).

 

[Silly Sausage]

What problem(s) is(are) this(these) new regulation(s) addressing?

 

[SparkyChick]

What problem(s) is(are) this(these) new regulation(s) addressing?

My guess is the frequency with which boards are being installed with an under rated RCD protecting a group of circuits.

I've just been to quote a job today and it was an Ashley and Rock board with an 80A RCD protecting I would say somewhere in the region of 180A worth of MCBs.

Even allowing for some diversity as per the OSG, the five 32A MCBs come out at over 80A. Whether this calculation provides a good reflection of the true load is irrelevant, it doesn't seem right that there is the potential there for pumping 100A through an 80A rated switching device.

 

[Baddegg]

Please bare with me here.....so assuming method 2, rccb is not less than main cut out fuse....is diversity then allowed over the mcbs?

 

[Silly Sausage]

My guess is etc ....

You maybe right, but BYB 120.1 & 131.1 state blah blah blah.
Can anyone cite me an example of, in the last 10 or 15 years or so, where non-application of these new regs have caused a problem?

Being cynical, what with AFDDs etc, there seems to be a lot of finding and enforcing solutions to (virtually) non existent problems occurring here.

 

[SparkyChick]

You maybe right, but BYB 120.1 & 131.1 state blah blah blah.
Can anyone cite me an example of, in the last 10 or 15 years or so, where non-application of these new regs have caused a problem?

Being cynical, what with AFDDs etc, there seems to be a lot of finding and enforcing solutions to (virtually) non existent problems occurring here.

I agree and may be a good reason why manufacturers should play no part in the writing of the regulations.

 

[Deleted member 26818]

Does seem that the caveat about adhering to the manufacturer’s instructions, allows them to hold us over a barrel.

 

[Nebu1a]

The total may add up to 160 amps but the DNOs main fuse is only 100 amps so the main switch is protected.