No RCD on entire installation

[sparky1508]

Hi all,

I have done a small job of installing a radial circuit and adding a spur to a ring final circuit.
I am not too sure about the existing installation. It is in a commercial premises office type with a single phase CU. I have an issue with the fact that there is not an RCD to be found. I think there should be one but I have done mainly domestic. Would it be possible to install a stand alone 30ma RCD before the CU or does it need a new CU. Please correct me if I am wrong.
Cheers

 

[Ian1981]

Hi all,

I have done a small job of installing a radial circuit and adding a spur to a ring final circuit.
I am not too sure about the existing installation. It is in a commercial premises office type with a single phase CU. I have an issue with the fact that there is not an RCD to be found. I think there should be one but I have done mainly domestic. Would it be possible to install a stand alone 30ma RCD before the CU or does it need a new CU. Please correct me if I am wrong.
Cheers

Does your new work require one cables buried in walls installing a socket for example?

 

[sparky1508]

Does your new work require one cables buried in walls installing a socket for example?

Yes, probably 1/3 of both ring final circuits is buried in the wall with plastic capping as I can see it coming out of the wall above the suspended ceiling. The rest is run round the perimeter of the office in plastic dado trunking with sockets.

 

[westward10]

Needed to undertake a risk assessment before works were carried as this requires a Minor Works.

 

[sparky1508]

I thought it was an EIC as I have installed a new circuit.

 

[Ian1981]

If you've installed a brand new circuit then it requires a eic

 

[westward10]

Thought it was from an existing circuit.

 

[Ian1981]

Yes, probably 1/3 of both ring final circuits is buried in the wall with plastic capping as I can see it coming out of the wall above the suspended ceiling. The rest is run round the perimeter of the office in plastic dado trunking with sockets.

If your cables you've installed are not in the wall then you might not need rcd protection for the cables anyway

 

[sparky1508]

Thought it was from an existing circuit.

The spur was from an existing circuit but I also reinstated an existing radial the had been disconnected by a previous spark. The reason it was disconnected was that they had floor sockets removed and the 2 MCB's labelled floor sockets were disconnected and removed. One of these had already been changed to a radial and was disconnected by mistake.

 

[westward10]

Commercial premises should have consulted client and carried out a risk assessment.

 

[westward10]

Not new circuits then.

 

[sparky1508]

This radial is directly below the CU. The ring final circuit I added a spur to has cables buried in the wall.

 

[Ian1981]

This radial is directly below the CU. The ring final circuit I added a spur to has cables buried in the wall.

Only the work you install needs to comply so if existing cables are in walls but the ones you install are not then you don't need an rcd for cables in the wall anyway.
If you want to improve the installation it's up to you and the paying client

 

[westward10]

Minor Works then, what does the new spur do.

 

[sparky1508]

Minor Works then, what does the new spur do.

It feeds a double socket in a small office to power a computer.

 

[7029 dave]

IMO, he has made alterations to the circuit, at the very least the spured socket should be off a RCD FCU or up front RCD in closure for the circuit in question.

 

[Ian1981]

Regs give 2 exceptions for not providing rcd protection to sockets up to 20amps and one is for providing one item of equipment suitably labelled for its purpose if you wanted to go down that route

 

[sparky1508]

Regs give 2 exceptions for not providing rcd protection to sockets up to 20amps and one is for providing one item of equipment suitably labelled for its purpose if you wanted to go down that route

So I could simply label the 2 double sockets for the servers and inform the client. Could I also label the spur as this is connected to an existing circuit.

 

[Ian1981]

So I could simply label the 2 double sockets for the servers and inform the client. Could I also label the spur as this is connected to an existing circuit.

It thought it was one double socket ?

 

[sparky1508]

It thought it was one double socket ?

One double socket on the spur and 2 double sockets on the reinstated radial.

 

[Ian1981]

One double socket on the spur and 2 double sockets on the reinstated radial.

For the one double socket you could label it after confirming it with the client and checking who's in control of the said socket, but for others I'd rcd protect them as regs do say
for a specific labelled or otherwise suitably identified socket-outlet provided for connection of a particular item of equipment.

I'd check with the clients risk assessment if any and their individual needs tho

 

[sparky1508]

The radial will only be used for the server equipment and I can speak to the client about making sure the spur is only used for said computer.

 

[sparky1508]

What about if the client says he would rather have an RCD installed? Would a stand alone 30ma suffice or would he need a whole new CU. Just trying to save him money as he is a regular client of mine but also want the installation to be safe.

 

[westward10]

Existing circuit note on the Minor Works, additional rcd protection not provided. Extent of Works, reconnect existing circuit to spare way...., DB.... New circuit either install an rcd socket or get the client to sign a document that additional rcd protection is not required me, fit an rcd socket.

 

[Wilko]

Personally, I won't extend or add a power circuit without RCD. Just saying

 

[westward10]

Personally, I won't extend or add a power circuit without RCD. Just saying

This is a bit different to domestic so you could escape additional rcd protection whereby the socket outlet is no different to a light switch because the employer is obliged to comply with the Health and Safety Work Act 1974, the Electricity at Work Regulations 1989 and the Provision and Use of Equipment Regulations 1998. Meaning any equipment connected to any socket outlet should be fit for purpose and safe to use whether rcd protected or not.

 

[Wilko]

Not arguing the logic of what you say, but I wonder if the employer understands that they are now "it" ?
If that was explained to them, maybe they'd cough up the £ to mitigate their risk? It would open my corporate wallet

 

[Ian1981]

There's also the fact of do you really want the server/cabinet on an rcd?
To the op can it be hard wired into a fused spur/outlet without possible voiding the equipment warranty and does the manufacturers instructions allow this?

 

[The Ghost]

Why not exchange the RCD for an RCBO

 

[sparky1508]

No room for RCBO's, CU already chock full.
I think I will speak to the client and see which direction he wants to go. I am personally leaning towards putting RCD sockets on all 3 that I have worked on. But if he chooses a main switch RCD is that something that can be done with a 30ma.

 

[davesparks]

But if he chooses a main switch RCD is that something that can be done with a 30ma.

That depends on what type of protection you want the RCD to provide.

 

[Wilko]

Hi Sparky - as Dave says it depends on the device and what you want it to do. If you look at Table 53.4 its got the standards and use approvals (read all the footnotes). Hope that helps

 

[Taylortwocities]

I am personally leaning towards putting RCD sockets on all 3 that I have worked on.

But that does not provide the required protection for the buried cabling.
Stand alone RCD at the DB end is the way to go, as there's no RCBO space.

 

[Octopus]

But if he chooses a main switch RCD is that something that can be done with a 30ma.

Not an option IMHO..............

 

[Taylortwocities]

Not an option IMHO..............

Concur. One fault will take out the whole office. Not what you, or the client will want.

 

[gazdkw82]

if you have had some mcb's taken out, have you now got room for fit an rcd?

 

[Taylortwocities]

He hasn't taken any MCBs out, has he?

 

[gazdkw82]

IM sure he said previously that there were 2 mcbs disconnected

 

[sparky1508]

IM sure he said previously that there were 2 mcbs disconnected

There was 2 disconnected, 1 of which I have reconnected and there is now only 1 spare way in the current CU.

 

[gazdkw82]

Enough room for an rcbo?

 

[sparky1508]

Enough room for an rcbo?

As above, no room for RCBO.
I have given the client his options and he has said he would like the sockets labelled for specific equipment. I know this does not have any safety aspect at all but he is the client and I can only do what he asks for.
Thanks for all the input and advice.

 

[Roofus]

From a different perspective: We don't install RCD's on circuits which have a number of servers due to tripping of RCD's etc. The servers power supplies filter out electrical noise which they dump to the CPC. So we cover this in our risk assessment and label sockets up for IT equipment only. You might want to check your earth cable is up to scratch for protective current flowing from servers and run additional earth cable if required.

 

[marc8]

No room for RCBO's, CU already chock full.
I think I will speak to the client and see which direction he wants to go. I am personally leaning towards putting RCD sockets on all 3 that I have worked on. But if he chooses a main switch RCD is that something that can be done with a 30ma.

if you look at the work you have undertaken on 3 sockets I would go for RCD protection local to the work you have undertaken, after testing the circuit you have joined on to. the reason for this if you put an upstream RCD in circuit & there is a problem on equipment it could trip & you could be blamed for the circuit tripping.
if circuit / circuits test out okay install a RCD socket outlet issue a minor works anything plugged in will trip your RCD socket only & not trip the whole circuit / circuits, at this point you have protected your work & covered yourself.

 

[marc8]

if you look at the work you have undertaken on 3 sockets I would go for RCD protection local to the work you have undertaken, after testing the circuit you have joined on to. the reason for this if you put an upstream RCD in circuit & there is a problem on equipment it could trip & you could be blamed for the circuit tripping.
if circuit / circuits test out okay install a RCD socket outlet issue a minor works anything plugged in will trip your RCD socket only & not trip the whole circuit / circuits, at this point you have protected your work & covered yourself.

& if for a server I would think twice about RCD protection as above post #42, I would tend to run in a new circuit for server & clean earth.

 

[Pete999]

IMO, he has made alterations to the circuit, at the very least the spured socket should be off a RCD FCU or up front RCD in closure for the circuit in question.

Or an RCD socket

 

[Taylortwocities]

Or an RCD socket

But that does not provide the required protection for the buried cabling.

 

[Pete999]

OK

 

[DPG]

If you fit a 30mA RCD up front of the dis board then you risk the whole lot tripping out on an earth fault. And if it's IT stuff in there then your total leakage current is going to be heading towards the trip current of the RCD anyway I would have though.

 

[Stspark]

I'd be looking to install rcbo's on the worked on circuits. Why do you say there is no room for this? Generally rcbo is only about 20mm longer than a mcb.
Other than that, instruct the client to provide a specific written risk assessment for the omission of rcd/rcbo on socket outlets circuits, which will need to be attached to the eic or mwc, good luck with that! Rcbo for me

 

[Taylortwocities]

Generally rcbo is only about 20mm longer than a mcb.

Many many legacy CUs just physically do not have a spare 20mm above the existing MCBs. Older ones often have solid neutral busbars and other obstructions that just make fitting an RCBO an impossibility.