surface mounted cables RCD or NOT?

[maddfridge]

Hi Everyone

A company has had its inspection failed for the following reason a Ring final circuit wired in pvc high impact 20mm conduit is not RCD protected. The situation is an accomodation block at a college inside the rooms with access corridoors.

!. The onsite gude states 3.6.1 pagees 21 and 22

(ii) Rcd required for socket outlets in domestic and similar installations

NOTE: Cables installed on the surface do not require Rcd protection

3.6.2 TN conduit installations

where cables in wall or partitions have an earthed metallic covering or are installed in steel conduit or similar 30ma rcd protection is still required in the following circumstances

in this case
circuits with socket outlets not exceeding 20A


They then stated that in the big red book

411.3.3

(rcd to 415.1 30ma taken as read) rcd shall be provided for

i) socket outlets with a rated current of not exceeding 20A that are used by oridnary persons and are intended for general use

Right now here we go

For the onsite guide cables in conduit not metallic are not in the wall but on it
so basic and fault protection are met by the mcb and conduit also mechanical protection.

if these are fullfilled additional protectuion by an rcd would not be needed but to cover all the additional protection by an rcd is an added bit of insurance.

So to get this by going back to the regs it effectively nulls the onsite guidance ??????????

ok we all know the onsite guide is only a guide but if the average sparks works to the onsite guide he falls down falt on intruptaion by an inspector ?

Solution is simple rcbos in the board job done

So should designer ignore the onsite guide and how practically would it affect the day to day installtions sparkie life

comments please
cheers

 

[Mac]

I found this on the ESC website.Hope it is of some help.I assumed that all ring mains had to be RCD/RCBO protected,especially in a college.
WNQ3
Which socket-outlets in commercial and industrial premises are NOT required to have additional protection by RCD?

​

WNA3
Socket-outlets in commercial and industrial premises must have additional protection by means of an RCD if they are rated at 20 A or less and are for general use without the supervision of a skilled or instructed person. An exception is made for a specific labelled/identified socket-outlet for a particular item of equipment.

The decision as to which socket-outlets are provided with RCD protection in accordance with these criteria should be made in consultation with the client’s duty holder under the Electricity at Work Regulations 1989.

As a general principle, it may be considered that socket-outlets in commercial and industrial premises NOT needing to have additional protection by means of an RCD include the following: a socket-outlet labelled for the connection of a specific item of equipment; socket-outlets not intended for general use, such as those in floor service boxes intended for the connection of workstations and other IT equipment; socket-outlets for use under the supervision of skilled or instructed persons so as to minimize the possibility of careless use.

See decision tree

411.3.3​

 

[TPES]

So cable that is surface mounted in any type of install does not need RCD protection?
Still apply for cable in YT2 for example?

 

[ian.settle1]

I found this on the ESC website.Hope it is of some help.I assumed that all ring mains had to be RCD/RCBO protected,especially in a college.
WNQ3
Which socket-outlets in commercial and industrial premises are NOT required to have additional protection by RCD?

WNA3
Socket-outlets in commercial and industrial premises must have additional protection by means of an RCD if they are rated at 20 A or less and are for general use without the supervision of a skilled or instructed person. An exception is made for a specific labelled/identified socket-outlet for a particular item of equipment.

The decision as to which socket-outlets are provided with RCD protection in accordance with these criteria should be made in consultation with the client’s duty holder under the Electricity at Work Regulations 1989.

As a general principle, it may be considered that socket-outlets in commercial and industrial premises NOT needing to have additional protection by means of an RCD include the following: a socket-outlet labelled for the connection of a specific item of equipment; socket-outlets not intended for general use, such as those in floor service boxes intended for the connection of workstations and other IT equipment; socket-outlets for use under the supervision of skilled or instructed persons so as to minimize the possibility of careless use.

See decision tree

411.3.3​

As Mac has quoted under the supervision of an skilled or instructed person, which may sound OK but if you are a contractor doing the install and then go away how do you know it is as the Regs state under the supervision of an skilled or instructed person?

 

[andekoch]

because it is an accommodation block for students I would RCD protect (for the socket outlets more than the cables) but non the less RCD protect due to the unskilled persons plugging in whatever.

 

[maddfridge]

because it is an accommodation block for students I would RCD protect (for the socket outlets more than the cables) but non the less RCD protect due to the unskilled persons plugging in whatever.

hi there

yes rcd is the answer but tripping is a problem with all the laptops, microwvaes etc.
my fav is the baby belling rings and oven

you then fall foul of the nuisance tripping reg cant recall it at the moment as students are not skilled persons etc rcbos is the answer but at what cost must be cheaper tan rcd socket fronts etc.

cheers all

 

[Mac]

Doing a refurb job at a University at the moment.All ring final circuits are wired in 4mm and RCBO protected on C type breakers even if they have 4 sockets on.That is what is specified.Can't see a problem with nuisance tripping.

 

[maddfridge]

Doing a refurb job at a University at the moment.All ring final circuits are wired in 4mm and RCBO protected on C type breakers even if they have 4 sockets on.That is what is specified.Can't see a problem with nuisance tripping.

hi there

3 sockets per room 3 rooms on 2.5 mm ring thats one of the issues.

i agree 4mm and rcbos heaven but we aint in heaven are we lol

cheers

 

[xraytek]

Hi Everyone

A company has had its inspection failed for the following reason a Ring final circuit wired in pvc high impact 20mm conduit is not RCD protected.

I assume you are talking about a PIR, and if that was the only issue then isnt that a little harsh?

I would have thought you could give a code 2 and an overall 'satisfactory' as basic measures of protection are adequate, and that supplementary protection (or possibly just a label) is all that is missing.

 

[pevvers]

I would say that you can't put a "satisfactory" report with code 2's in it.

If the sockets are not likely to supply portable equipment outside then it would be a 4 for me every time, if not, then a 2.

 

[xraytek]

Hi Pevvers,
I just had a read of the PIR best practise guide published by the ESC (Link for anyone interested).

It does agree with you that a code 1 or 2 cannot be given an overall satisfactory.
I was of the missunderstanding that only code 1s instantly warrant a fail, whereas code 2s were at the discreation of the inspector to decide on an overall pass.

The guide also lists the non-RCD socket issue as a code 4 if the sockets are not supplying equipment outdoors.

 

[pevvers]

It is indeed a good guide, and if the poo hits the fan and someone disagrees with you you always have something in writing from a recognised place.

It's the same guide on codes more or less as which is in the NIC's domestic PIR book, which is also a very useful book to have a flick through, as I'd always done commercial/industrial until my company got the contract to do PIR's on a load of scummy housing association (read council) houses. It helped me no end!