UK Type B RCDs for fire protection?

[GBDamo]

Hi all, not been around in a while but I'm working through a quote at the moment and found this at the end of the equipment (AC kit) suppliers quote.



From the icons provided were definately talking B type and not B curve.

For the job in question this one paragraph statement could add upwards of £10k to the electrical quote.

There are seven outdoor units and forty-four indoor, across 8 circuits.

The DB for the outdoor units will be a new, dedicated, install and could arguably be up front protected but this approach has it problems.

TP 40A type B RCCBs range from £650-1200 each.

SP 32A type B RCDs don't exist in a single module (schneider Acti9) and would require major modifications.


I've not come across B type RCDs being specified for fire protection.

The research I've done makes no mention of fire protection provision by type B rcds.

Yes, these are inverted devices and may blind other type RCDs but there in no other regulatory requirement for an RCD other than this Manufacturer's Instruction.

What are peoples thoughts on this.

I am trying to talk to someone at the manufactures but they are a global mega Corp and getting hold of a person is nigh on impossible.

 

[pc1966]

What sort of a device are they?

Do they need individual 30mA RCD protection as plug/socket or are they something that would not normally need it under UK regs?

The high current RCD incomer for fire is usually an agricultural aspect in the UK. If they are not very leaky individually you might be OK with one up-front 300mA type B delay RCD for the lot (including circuits on RCBOs for sockets, etc).

Recently I changed a 30mA RCD to 100mA delay for a solar inverter as it occasionally tripped, manufacturer also suggested 300mA to avoid spurious trips (could be type AC, they explicitly said so, and delay if many devices) even though it only measured 2.4mA steady-state.

 

[GBDamo]

What sort of a device are they?

Do they need individual 30mA RCD protection as plug/socket or are they something that would not normally need it under UK regs?

The high current RCD incomer for fire is usually an agricultural aspect in the UK. If they are not very leaky individually you might be OK with one up-front 300mA type B delay RCD for the lot (including circuits on RCBOs for sockets, etc).

Recently I changed a 30mA RCD to 100mA delay for a solar inverter as it occasionally tripped, manufacturer also suggested 300mA to avoid spurious trips (could be type AC, they explicitly said so, and delay if many devices) even though it only measured 2.4mA steady-state.

They are AC units, like I said the upfront on the new board is a possibility but retrofitting into the MG isobar boards will be a pain, probably have to migrate the circuits to an small CU with upfront Type B RCD protection.

But WHY, its annoying me.

Still waiting on 'technical help'

Edit, no other need for RCD protection.

 

[pc1966]

They are AC units, like I said the upfront on the new board is a possibility but retrofitting into the MG isobar boards will be a pain, probably have to migrate the circuits to an small CU with upfront Type B RCD protection.

A quick search shows very few delay type-B RCDs available, and if found they are crazy expensive such as this:

80A 4 Pole 300mA Type B Selective Time Delay DC Sensitive RCD

VISI-SAFE for safe operation and maintenance work

www.cef.co.uk

But WHY, its annoying me.

Maybe just manufacturer pushing problems on to installer.

Though the Doepek info on their RCDs mentioned "VDE German installation standards: fire protection < 420mA" so it might be something that is more common in the EU where TT is more common.

If no "additional protection" needed and it meets Zs for ADS I do wonder how much the type B aspect matters. Clearly it would for TT where a shock hazard is present from a blinded RCD, but here I am less convinced.

Still waiting on 'technical help'

Edit, no other need for RCD protection.

Good luck!

 

[NateCreekside]

If you can think of an acceptable(cheaper) work around that you'll happily justify, can't you just note that down on the EIC?

 

[GBDamo]

If you can think of an acceptable(cheaper) work around that you'll happily justify, can't you just note that down on the EIC?

That really is the issue from a BS7671 compliance point of view the easy work around is to omit them altogether, ADS is met and no need for additional protection.

Until the 'technical help' get back to me I've no idea what their requirement is.

"Fire protection" for me doesn't cut it unless they were installed in national monument or somewhere a fire may hinder the egress of vulnerable people, neither of which apply.

Just have to wait and see.

At the moment the quote is submitted with the proviso that approx £5k of the work is subject to technical confirmation.

 

[GBDamo]

Just got a reply from the OEM....

Damion,

Please see below from our product team

"these are more generic recommendations. reality is we would defer to local best practices/regulations."

A bit of an explanation would have been nice but either way it is good to get a definitive answer in writing.