RCD Protection for submains

[TJC1]

Evening all

We have been asked to do some redial work picked up by a testing company i a hostel. It has been picked up that is no RCD protection in the rooms

There are 5 submain circuits that feed the 20 consumer units, 4 consumers units per submain (B32) Each room have a consumer unit which has two double sockets off a 16a radial and a lighting.

They asked my advice on whether to change the submain MCB to RCBOs or whether to change the consumer units for main switch and RCBOs

They supply cables to each consumer unit are above a plasterboard ceiling but cant be sure of the installation method, does the submain need to be RCD protected? As i dont want to put RCBOs on each circuit and also on the submain also

Thanks

 

[Deleted member 26818]

The thing is we don’t know when it was installed. We also don’t know if the guy who issued the report is aware of the changes between the 16th and 17th. My point is that I’d like to know these facts before banging in RCD’s.

Personally, If I’m asked to provide RCD protection, the age of the installation doesn’t matter.
I’ve done some work for a customer who owns a Cafe.
Installed a split load board a few years back, installed a new circuit for his dishwasher, installed some 600mm X 600mm LED lights, and a few other things.
Not all at the same time, but over a period of years.
The latest was to swap out the innards of the split load board and replace with RCBOs.

 

[45140]

The client may well have done a risk assessment and the remediation is the provision of RCDs given it is a hostel, so surely the basis upon which it was wired is hardly relevant ?

The correct solution would be an RCD for each room for obvious reasons and is surely the right answer ?

 

[Bait Account]

The client may well have done a risk assessment and the remediation is the provision of RCDs given it is a hostel, so surely the basis upon which it was wired is hardly relevant ?

The correct solution would be an RCD for each room for obvious reasons and is surely the right answer ?

We don’t know that bud but it is possible. It’s also possible that the person that carried out the report wasn’t aware of the requirements of additional protection in the previous editions of the regs. Anyway we can speculate all night as I doubt we’ll ever know the full facts.

 

[Toneyz]

The answers you seek are in BS7671

In that case my preference would be RCBO's to each circuit.

 

[westward10]

When I do EICRs I am not overly interested when it was installed with regard to additional protection it is a statement of fact it is not provided.

 

[Bait Account]

When I do EICRs I am not overly interested when it was installed with regard to additional protection it is a statement of fact it is not provided.

Yea bud but that statement of fact has to be coded so 16th would be a C3 and 17th a C2.

 

[Deleted member 26818]

When I do EICRs I am not overly interested when it was installed with regard to additional protection it is a statement of fact it is not provided.

Only difference the date of design/construction would make, would be to the code applied.
If it warranted a code C3 and the client wanted the C3s rectified, then rectify the C3s.

 

[westward10]

Don't get into Code debates anymore.

 

[Ian1981]

Date is never relevant on an EICR.
It’s tested to the current edition and a code given if deemed a safety concern ,whether it complied before to the 14th,15th,16th or 17th,is irrelevant.
Existing installations may not be unsafe in that respect but non compliance’s giving rise to danger must be recorded regardless of age.
Why this keeps coming up for debate is ridiculous.

 

[Upton Sparks]

The basic issue is the sub mains are a pvc cable buried in the fabric of the building and there is no RCD protection to any of the fuse boards within the room and associated circuits or on the the sub main cable.

regardless of when it was built its a Commercial property so health and safety law will Trump over old regs rule, if there is a perceived risk then it need to be acted on.

(Personal I would c2 unless they had the original certificate with as build drawing and as wired. If you don't know where the Sub main cables are buried in the walls then there is a real danger to maintenance staff / general contractors . As it a commercial building .)

If you go for the 30 mil RCBO on the sub main you need to be careful, as a fault on a circuit in the rooms from the fuse board would trip the sub main RCBO first. which mean reg 314 (I think top of my head ) segregation of circuits would apply, and the installation would not conform to that.
you would then need to put 10mil amp RCBO in the fuse board in the room to obtain correct discrimination for the RCBO's
Or replace the sub main to an appropriate cable with mechanical protection and just put 30 mil RCBO's in on the rooms.

There is no cheap way out I'm afraid .

 

[DPG]

You'd still struggle with descrimination if you had a 30mA feeding a 10mA though.

 

[Upton Sparks]

Yeah possibly but your have half a chance and your be compliment with the 18th edition .

Personal I would look at replacing the sub main to an SWA. But that's a significant cost to the customer.

 

[Deleted member 26818]

Date is never relevant on an EICR.
It’s tested to the current edition and a code given if deemed a safety concern ,whether it complied before to the 14th,15th,16th or 17th,is irrelevant.
Existing installations may not be unsafe in that respect but non compliance’s giving rise to danger must be recorded regardless of age.
Why this keeps coming up for debate is ridiculous.

Yes it is ridiculous.
It’s ridiculous that people advise testing to the current edition, while at the same time advise ignoring the current edition?
I guess until people stop ignoring the current editions, this debate will continue.

 

[Nigel]

Yea bud but that statement of fact has to be coded so 16th would be a C3 and 17th a C2.

That is a ridiculous comment.

 

[Nigel]

Only difference the date of design/construction would make, would be to the code applied.
If it warranted a code C3 and the client wanted the C3s rectified, then rectify the C3s.

The date of installation bears zero alliance with how safe it is.