RCDs or Not ?

[treadeager]

Greetings All , my first post ! I am not a Sparks but would really appreciate the wisdom of your Forum members.

I work in a modern University . Built about 5/6 years ago . Some of the Laboratory and Studio power circuits have had major modifications in the past two years i.e. post 2009 . ( 32A ring mains , protected by circuit breakers as a minimum ) .

My understanding of the 17th Edition , tells me that these circuits SHOULD have RCD protection ! ( I am not worried about the tripping risk to a small amount of IT equipment ) . Am I correct in thinking that this should be a legal requirement , or is it just an optional extra at my employers discretion ?

Thanks in advance .

 

[telectrix]

if the installation ( i.e sockets,etc.) is under the supervision of a skilled/instructed person, there is no need for RCD protection on sockets, unless for use outdoors.

 

[treadeager]

if the installation ( i.e sockets,etc.) is under the supervision of a skilled/instructed person, there is no need for RCD protection on sockets, unless for use outdoors.

Telectrix , thanks for your swift response . The areas that I am concerned about ( as a Health & safety Coordinator ) are used by Students , often unsupervised eg in the evenings . Typically they will plug in their laptops and phone chargers , but may from time to time want to use other 240v equipment ( perhaps a hot glue gun or something of that nature )

I was hoping that by having RCDs installed , basic equipment as above might be permissable , but if the University insists that the installation is correct ( No RCDs ) should I simply forbid students to use any 240v equipment at all ? ( subject to usual risk assessment procedures )

Hope this clarifies my concerns !

 

[telectrix]

hmm, in that case , i would mention your concern to the uni., and get them to carry out a risk assessment, it may be the way forward to fit RCD sockets wherever students play. ( sorry, work) unsupervised.

 

[jase]

depends on the installation method, when we do large comercial buildings often we use Tray or basket in the ceiling void and run LSF twin and earth dropping off into 25mm steel conduit for socket and switch drops, with the back boxes earthed via a fly lead, in this situation the regs do not require RCD protection.

 

[malcolmsanford]

To be honest I would have assumed that if there had been a major re-modernizing of the facilities and electrical system in your campus that the design, installation and testing of the system would have been carried out under strict guidelines draw up between the university, possibly a team of designers and the contracting company.

I can not imagine this refurbishment was carried out by Dave from down the pub who designed it on the back of a smoke packet, a couple of his mates and some cable left over from Sid's house.

If the design 2 yrs ago never called for RCD protection then I'm sure somewhere there is a ream of paperwork saying so.

Has the criteria for the installation changed, that it is now being used for what it was not designed for ?

 

[treadeager]

To be honest I would have assumed that if there had been a major re-modernizing of the facilities and electrical system in your campus that the design, installation and testing of the system would have been carried out under strict guidelines draw up between the university, possibly a team of designers and the contracting company.

I can not imagine this refurbishment was carried out by Dave from down the pub who designed it on the back of a smoke packet, a couple of his mates and some cable left over from Sid's house.

If the design 2 yrs ago never called for RCD protection then I'm sure somewhere there is a ream of paperwork saying so.

Has the criteria for the installation changed, that it is now being used for what it was not designed for ?

Thanks all for you comments .

Of course , the original specification for the infrastructure was very high ! But then the financial chaps " value-engineered " it .

 

[Deleted member 26818]

"Introduction to BS7671:2008
BS7671:2008 Requirements for Electrical Installations was issued on 1st Januaey 2008 and came into effect on 1st July 2008. Installations designed after 30th June 2008 are to comply with BS7671:2008.
The Regulations apply to the design, erection and verification of electrical installations, also additions and alterations to existing installations. Existing installations that have been installed in accordance with earlier editions of the Regulations may not comply with this edition in every respect. This does not necessarily mean that they are unsafe for continued use or require upgrading."

"411.3.3 Additional protection
In a.c. systems, additional protection by means of an RCD in accordance with Regulation 415.1 shall be provided for:
(i) socket-outlets with a rated current not exceeding 20A that are for use by ordinary persons and are intended for general use, and
(ii) mobile equipment with a current ating not exceeding 32A fir use outdoors.
An exception to (i) is permitted for:
(a) socket-outlets for use under the supervision of skilled or instructed persons, or
(b) a specific labelled or otherwise suitably identified socket-outlet provided for connection of a particular item of equipment."

Dealling with College Administration can be a nightmare.
I hope the two quotes above will be of some help.
You first need to establish when it was decided to install the new circuit, and the date the circuit was designed.
If it was designed before the commencment of BS7671:2008 (the 17th edition), then there is no requirement for it to comply with the 17th edition.
If however you establish that it does need to comply, then you have to ascertain what was the intended use of the socket-outlets.
If the socket-outlets were intended to supply specific items of equipment such as a fridge, washing machine, drinks dispencer, computer, printer, etc. then there is no requirement to provide RCD protection.
If however they were intended to be for general use, and they are used (unsupervised) by students (students would not normally be classed as skilled or instructed), then either RCD protection or supervision is required.
It is a bit of a silly situation, as you can have an existing socket-outlet that can be used by anyone, and a new socket-outlet installed next to it that can only be used by certain people or with their supervision.
There are other reequirements that might entail RCd protection be provided, but they are to do with how the circuit has been constructed, and most likely do not apply in this case.

 

[GT1]

Just a side note.
Could it be possible that RCD protection is provided for, upstream of your local DB.?
If not RCD then similar device affording the extra protection needed.?
As others have said if the cables are buried in walls, not less than 50mm, or not otherwise protected from mechanical penetration etc etc, then it would have attracted the need for RCD protection anyway.
Skilled or instructed persons can be a "bit" subjective, but the erection method is pretty black and white.

 

[Deleted member 26818]

There is an exception to the requirement to provide RCD protection for cables concealled in walls, for when the installation is under the supervision of a skilled or instructed person.
As this is not a domestic installation, then it is a statutory requirement that the installation is under the supervision of a person who would satisfy the requirements of BS7671 to be deemed a skilled or instructed person.

 

[SimpleSimon]

If your really worried about what the students are actually plugging into the sockets as opose to the care of the cable behind the walls than possibly RCD sockets would satisfy it more?

Sent from my GT-I9100 using Tapatalk

 

[treadeager]

Thanks all once again !

I do not believe there is any further upstream RCD protection .

RCD sockets are probably not the comprehensive solution as there are approx. 12 off twin sockets plus 3 off suspended " powercube " pendants , each with 2 off all on separate fused spurs .

Some of the original cabling does indeed appear to be buried into walls.

 

[Deleted member 26818]

The cables being concealled in walls is not really an issue here.
There is no requirement for RCD protection to cables concealled in walls, if the installation is under the supervision of a skilled or instructed person.
The Caretaker, or whomever is in charge of the maintenance will be a skilled or instructed person.