Nuts for RCDs!

[Dan23584]

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.

 

[Deservices]

Now I am not getting involved in a argument, but it is down to interpretation. IT equipment will leak to earth therefore causing a RCD/RCBO to trip if to much is installed on one circuit. This is what the OP wanted to avoid. Now the sockets wont be used or constantly monitored by a skilled person. As to do that would be bloody expensive to employ effectively retail assistants.

The customer has not stated they dont want the sockets RCD protecting as again the OP has said he has done the design, install and testing.

So the only way I see it possible to do this would be too.

A. Work out earth leakage of each item of equipment
B. Install enough circuits so that none reach the limits of nuisance tripping
C. Install each circuit on a RCBO

He would also do the design based on what they wanted. But as he's not stated they didn't want RCD protection, I would also of fitted one if not been requested not to. but of told them possible trips and adjusted needed ie maybe run a few radials.

 

[Jimmy Boy]

I don't see any confusion, he has applied section 411.3.3, and used exceptions a, or b, under this reg, as long as the sockets are under the supervision or a skilled or instructed person ( IMHO this should be noted on the cert ) OR the socket outlets are labelled for use with a particular item of equipment he isn't in contravention of the regs, but I still await the OP's response to my earlier question why he thinks RCD protection only applies to domestic dwellings ?
ATB
J

 

[Deservices]

The term mobile is for a item that is moved while it is plugged in ie floor cleaner lawn mower not commuter monitor.

 

[Jimmy Boy]

TBH I think it is going a little off track, the question is, will those sockets be used or be LIKELY to be used by 'ordinary' persons ?..answer yes, then apply the regs RCD them, answer no, then use the exceptions in the regs, but, and here is the rub, I can foresee very very few office situations, where you can reasonably guarantee that no one other than those skilled or instructed persons will use those sockets, the cleaners come in a ten at night use the sockets, or some maintenance man, too many variables for my liking but as I say it's down to the signatory ! It's his head on the block if it goes pear shaped !
J

 

[Engineer54]

Far too much being read into this, ...exactly what are you expecting to go wrong, if and when the instructed person is out of the room/office?? He has stated the dedicated outlet for the cleaner has been RCD'd??

You simply can't cover every single possibility of usage of a circuit, that is out of any electricians control. As far as i can see there is nothing wrong with the OP's installation. ...And no he won't have his head on the block!!

 

[dagrat]

I agree with Engineer 54,I think that the regulation as it stands refers to installations that come under the control of a competent person, and therefore does not necessarily refers to persons using the computer.
One reason the RCD regulation is relaxed in these situations is because it is assumed (for example) that any drilling in these locations will only be undertaken by a skilled and competent person. So no probs

 

[oldtimer]

Good discussion guys and me thinks we are missing the point as we are all lead to believe that RCDs were introduced because an MPs daughter was sadly killed but me I am more cynical than this I think because RCDs became more economically viable the MPs daughter was used as a vehicle for interested parties ie the Scheme providers to strengthen their position within the industry and at the same time they get to ride on the back of improving safety . Also they thought via Part Pish they thought they could control the domestic environment but stayed well clear of trying to force it on the commercial and industrial sector. Remember the you cannot back date the regs but you put it in such a way that if you make changes then you need to apply them.

Now as for CEF being in the industrial and commercial class well yes but there is one problem their when you walk in they have a lot of lighting displays so in a sense they have to be RCD protected even although the majority of the people on the customer side are electricians they have to be treated as Joe Publics

 

[smu_diddly]

I don't think cef will have enough IT equipment to cause an rcd to trip, you would need like a huge office full of them to produce enough leakage to trip. If all other circuits are in conduit then fine leave the rcds off them but stick an rcbo on the sockets. I wouldn't take the risk.

 

[imago]

exactly what are you expecting to go wrong,

Well they used Proteus gear, so .........

 

[Engineer54]

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....

 

[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. ;-)