Nuts for RCDs!

[imago]

Will someone please tell me what far out and away risks were talking about here. these sockets were talking about are in metal conduit containment, so no-ones going to be putting screws or pins through the wiring. Assuming that the ADS is well up to specifications, tell me what risks are we talking about on these IT/computer dedicated outlets....

To be honest I don't think the issue is one of risk, it's more one of arse covering by ensuring that the regs are fully complied with. Common sense and an individual assessment are now banned under the "2012 Follow the book blindly act."

I think the root of some of these dilemmas is the OSG, which whilst handy has dumbed down a lot of the regs and left out some of the "you work it out you're the electrician!" statements. In the OP's case, it's a light industrial/commercial unit. He's taken all reasonable factors into account, done the calcs, made the design, job sorted. Would I have done it in the same way using the same design? Unlikely as everyone works sligtly differently. Neither approach would necessarily be incorrect.

I do think the nuisance tripping spectre is vastly overplayed though. I'm always more interested in the nuisance death issue

 

[oldtimer]

20 years ago I worked as an In Store Technician at Marks & Spenser's and they had a jewllery cabinet that was moved around the store from pillar to post and every time it was moved I had to get involved well one day I said thats it no more moves until I get a RCD safety breaker fitted to this . Well nope one week later manager said move it or I will tell your company to sack you no sorry I said the RCD comes in a couple of days so i was not the flavour of the month so I fitted it not in the unit but at the top of the pole where it plugged in to a lighting track again grief I dont like the look of that box at the top of the pole but hey hoa .

One month later emergency fax came through a 10 year old child was thrown across the shopfloor when he touched the pole it was found that the pole had become live because of it getting moved around the store and strict instructions to disconnect it and fit a RCD to it I faxed back already done this a month ago plus fit the RCD at the top of the pole because if you dont it wont prevent what happened again.

So as I said on the public side of the counter then RCD all the way the funny thing was the manager of my store got a pat on the back for being so proactive but never came up to me to either thank me or apologise for trying to bully me . Funny old world

 

[Guest55]

the responsibilities of the electrical designer / installer have become confused with the responsibilties of the building duty holder in this thread.

bs7671 gives multiple options to an electrician to omit rcd's in certain circumstances - no regs are being broken at all if a designer decides to take this route using
a. his engineering judgement
b. a risk assessment on how the installation will be used
c. the clients requirements / wishes.

if rcds are not fitted to computer sockets in agreement with the buildings duty holder then responsibilty for how these sockets are used lie with that person , not with the electrical designer / installer.
therefore if the cleaner plugs faulty vacuum into a socket used for printers and gets a shock then the duty holder has failed to a. supervise & train persons using the installation and b. not have electrical equipment used on the premises inspected or maintained properly - no blame lies with the person who signs the cert.
the OP is perfectly correct not to fit rcd's to circuits that supply IT equipment if the cables are not buried in a wall and will not be used by the general public.

 

[Jimmy Boy]

the responsibilities of the electrical designer / installer have become confused with the responsibilties of the building duty holder in this thread.

bs7671 gives multiple options to an electrician to omit rcd's in certain circumstances - no regs are being broken at all if a designer decides to take this route using
a. his engineering judgement
b. a risk assessment on how the installation will be used
c. the clients requirements / wishes.

if rcds are not fitted to computer sockets in agreement with the buildings duty holder then responsibilty for how these sockets are used lie with that person , not with the electrical designer installer.
therefore if the cleaner plugs faulty vacuum into a socket used for printers and gets a shock then the duty holder has failed to a. supervise & train persons using the installation and b. not have electrical equipment used on the premises inspected or maintained properly.
the OP is perfectly correct not to fit rcd's to circuits that supply IT equipment if the cables are not buried in a wall and will not be used by the general public.

I make you right I think I had made that clear from outset, the only thing I take issue with Biff is your terminology if I am wrong then correct me, it's for protection of 'Ordinary persons' not the general public, and ordinary person could be an employee and yet not be a member of the public,also even if the cables were buried then RCD protection could be omitted if said wiring was again under the supervision of a skilled or instructed person 522.6.102. on.
ATB
J

 

[Guest55]

an employee , whilst in the work place , is not an ordinary person but an instructed person , under the supervision of the duty holder.
but i get your drift JB. ;-)

 

[Jimmy Boy]

an employee , whilst in the work place , is not an ordinary person but an instructed person , under the supervision of the duty holder.
but i get your drift JB. ;-)

Why Biff ? Under definitions in the regs 'instructed Person' is A person adequately advised or supervised by skilled persons, to enable him/her to avoid dangers which electricity may create.

A 'Skilled' person is someone that has technical knowledge of or sufficient knowledge of electricity to avoid dangers that electricity may create.

How many employees fall in to either category ? Not many I bet ! LOL
J

 

[UNG]

Reading this, Makes me wonder how we have all survived without RCD devices over all these years... We should all be dead or frightened to switch a light or socket on...lol!!

I'm with Dan on this one, far too much reliance on the all singing, all dancing ''Cover All'' RCD devices these day's. They are NOT always required on every circuit and in every situation...

I was thinking the same, I was taught that an RCD (ELCB as they were then) was a secondary protection device and I still consider them as secondary protection seen too many of these things not trip when they should to put total faith in them

Myself yes I would.

Do the items plugged in need PAT? That makes them portable.

What happens when the manager is off work, out of the office etc ? Too many variables in a office to say only one person has to be competant.

Not sure what PAT has got to do with RCD's or are we just trying to cover up for the bad PAT testing that appears to be the norm these days

 

[Guest55]

why ?
because the duty holder does not have to be electrically skilled to supervise users of his installation - just to be aware of the potential risks.
because the duty holder is governed by the Electricity at Work Regulations , not bs7671.

 

[Jimmy Boy]

why ?
because the duty holder does not have to be electrically skilled to supervise users of his installation - just to be aware of the potential risks.
because the duty holder is governed by the Electricity at Work Regulations , not bs7671.

I agree Biff in this case the statutory document takes precedent over the non statutory, not sure it makes them 'Instructed' tho..
but I get your drift
J

 

[Guest55]

not sure it makes them 'Instructed' tho..
but I get your drift
J

well if you , the installing electrician and a skilled person , instructs the duty holder in how to safely manage use of his sockets then he becomes instructed doesnt he ?
:-D

 

[johnboy6083]

When I installed the Dado sockets for the our companies office before the staff moved in, I decided to have them on MCB,s and not under RCD protection. There were already existing RCD protected sockets lower down on the wall which I designated dirty sockets, for heaters, fans and the cleaner. All circuits in the kitchen are RCD protected ect.

Obviously we definately have skilled persons looking after the installation, but I'd there weren't, then I would still install in the same way.

 

[Jimmy Boy]

well if you , the installing electrician and a skilled person , instructs the duty holder in how to safely manage use of his sockets then he becomes instructed doesnt he ?
:-D

Possibly lol..I can't say I remember seeing that in the EAWR or are we back to 7671 this time ? LOL !

J

 

[Guest55]

well i'd expect a "competant" designer to consider any and all regulations that may apply to the use of his planned installation , not just bs7671.
im bowing out of this thread now JB , i cant make my explanations any clearer can i ?

 

[Jimmy Boy]

I think you have made a valuable contribution Biff thanks
J

 

[shagbite]

Did you use a Proteus board then lol

you want to see the last proteus board that i took out. i've no idea how the place didn't burn to the ground. if i knew how to upload photo's i'd show you. got any tips?

 

[sparks1973]

Has anyone else experienced other sparks going nuts for RCD's and thinking they are required for pretty much everything?

I recently did the installation at my local CEF branch and had another spark telling me I should have fitted a dual RCD board! I reminded him that the install was in trunking and conduit ( no less than 50mm issue) and also not in a domestic situation. All sockets were in The office, apart form an outside RCD socket and a couple of sockets in the warehouse that were on an rcbo ( they were near the door to outside).

He still said "well I think it's good practice to fit them in most situations for optimising protection". I just bot my tongue told him to check his regs book and went on about my merry way.

suppose its a `cure all`...1667 n all that lot...lol...

 

[Jimmy Boy]

suppose its a `cure all`...1667 n all that lot...lol...

'Eh ? I don't think so ! Not on this installation !

 

[malcolmsanford]

'Eh ? I don't think so ! Not on this installation !

Zs value for a 30mA RCD is 1667 .................on any installation

 

[Jimmy Boy]

Zs value for a 30mA RCD is 1667 .................on any installation

Yep ! Not on any installation only those circuits in an installation that has RCD protection, the 1667 thing is often 'qouted' as a max, if you look at table 41.5 it is clear for any professional to see that this figure relates to a TT system where a satisfactory Zs cannot be achieved, and with the warning that a value> 200 ohms may be unstable,the 1667 should never be used as an excuse to circumvent table 41.3

J

 

[Dan23584]

That's for all the input guys, sorry but I'm now on holiday with limited/unreliable Internet so have had a little trouble reading all the posts.