Electrician installed a whole installation RCD

Hi,
In a small commercial office that was covered by a 12 way Wylex fuse consumer unit (that had been "upgraded" with MCB's), an electrician installed a whole installation 30mA RCD recently.
This installation covers about 10 rooms, which includes a total of 8 PC's and associated IT kit.
We are getting this RCD tripping randomly, he came out today, and I asked if he could firt an 100mA RCD for now, but as he didn't have one with him, and we need people to be able to work, he is going to replace the RCD with an isolator "At our request"
My question is, is it against the regs to install this whole installation RCD in this situation in the first place?
He said it was done because he fond one of the lighting circuits upstairs didn't have any earth, and this was the easiest way to protect this.
I basically want to know if we should use him to replace the CU with a new 17th edition one, probably with RCBO's, or we need to find another electrician.
Thanks!
--
Toby...
Remove your pants to reply
  Click to see the full signature.
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
On 09/11/2015 10:57, Toby wrote:

Its certainly a deprecated way of designing things, and probably not really meeting the requirement to maintain discrimination (i.e. limiting the effects of a fault in one part of an installation on other unrelated circuits)

Easiest for him perhaps...

Assuming his quality of workmanship is ok, then he ought to be able to do an all RCBO install since there is not much in the way of decision making ;-)
--
Cheers,

John.
  Click to see the full signature.
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
On 09/11/2015 10:57, Toby wrote:

I think a single RCD protection is ok as long as you have emergency lighting.
Given your setup and the potential loss of data etc when a trip occurs, I wouldn't have any hesitation to have a full RCBO setup.
In theory he should be able to test insulation of your boiler, and a PAT check on your other items if need be.
I have known PC PSUs to cause nuisance trips. In reality after investigating and ruling out the obvious boiler, it could be anything!
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
On Monday, 9 November 2015 10:55:27 UTC, Toby wrote:

He could have put a RCD FCU on the supply to the lighting circuit if that w as all he was worried about.
And I think the fire alarm panel (if it's a commercial panel system) MUST N OT be on an RCD circuit but should be on a protected cable like MICC or Fir eproof which does not need RCD protection, connected as close as possible t o the origin of the installation.
If he's taken your fire alarm installation out of its BS compliance then th ere may be costs to correct this at the next annual inspection, and insuran ce implications meantime.
Anyone putting a single RCD on an installation with 12 circuits these days needs their understanding of the Regs questioned.
Owain
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
On Monday, 9 November 2015 10:55:27 UTC, Toby wrote:

You can determine the cause by leaving items turned off one by one until the problem stops. Start with stuff that only runs intermittently.
All your portable equipment should be PAT tested anyway.
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload

However, a PAT test won't necesarily show up a fault which is either intermittent or takes time to develop.
--
Please note new email address:
snipped-for-privacy@CandEhope.me.uk
  Click to see the full signature.
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload

That's what all the PAT testers tell you.
PAT testing is a con.
--
Adam


Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload

PAT testing - because one year is up since the last test IS a con. PAT testing on a proper risk assessed basis can show up faults - but most are seen on the visual bit for which you don't need a meter. I have some RED stickers and I have used them. Once on a piece of brand new kit.
--
Please note new email address:
snipped-for-privacy@CandEhope.me.uk
  Click to see the full signature.
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
wrote:

Thanks for the link. Under the first 100mA entry in the table, page 4, it says: "For an installation forming part of a TT system, a 100mA RCD is generally installed at the origin. A time-delayed or 100mA ‘S-type’ (or selective) device is often used to permit discrimination with a downstream 100mA device". Reg. nos. 413-02-19, 531-02-09, 314-01-02
So as you say, appropriate for a TT system.
The diagram on page 3 "Discrimination achieved" is pretty much what I have, although of course differing in exact detail.
--

Chris

Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload

Fine if you have an unlimited budget, as so many of these places seem to. IMHO, totally unnecessary for a small office.
--
*"I am " is reportedly the shortest sentence in the English language. *

Dave Plowman snipped-for-privacy@davenoise.co.uk London SW
  Click to see the full signature.
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
On 10/11/15 11:13, Dave Plowman (News) wrote:

What on earth are you on about?
The sum total of RCD sockets in my place is a few % at most of all sockets.
I did say: certain common/accessible areas. I did not say every office, lecture room, corridor.
It's certainly cheaper to do what they did than upgrade the circuit (bearing in mind then they'd have to test the circuit possibly with dozens of sockets, and these are commercial breaker panels so I expect RCBOs will cost a little more than domestic ones).
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload

Then you must have many with no RCD protection. To give the same degree of protection, they'd all have to be RCD outlets. And have you looked at the cost of them? At least four times that of a non RCD outlet.

It would be a very brave person who would guarantee there was never a need for RCD protection on some sockets, while accepting it was needed on others. In any form of public building.
--
*I am a nobody, and nobody is perfect; therefore I am perfect*

Dave Plowman snipped-for-privacy@davenoise.co.uk London SW
  Click to see the full signature.
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
On 10/11/15 15:14, Dave Plowman (News) wrote:

If you read back, my point was that universities DON'T tend to have RCD protection on all sockets - very few IME out of a small sample set.

There'd seem to be a lot of brave people then... Remember, it's not a domestic environment, nor one deemed to have vulnerable people.
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload

Our local authority, in the case of village halls says "sockets on stage" must be RCD protected.
--
Please note new email address:
snipped-for-privacy@CandEhope.me.uk
  Click to see the full signature.
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
replying to charles , westom wrote:

Nothing should fault at even 2 milliamps. If something is tripping a 100 ma RCD, then an appliance or some household wiring has a major defect. Find and fix that serious human safety issue. Never cure symptoms - ie blame an RCD. Find and fix a human safety defect.
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
On 10/11/15 21:44, westom wrote:

work out what the leakage current of 30 PC RFI units with 15nF caps from live and neutral to earth is.
Well over 30 mA IIRC

--
the biggest threat to humanity comes from socialism, which has utterly
diverted our attention away from what really matters to our existential
  Click to see the full signature.
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
replying to The Natural Philosopher , westom wrote:

Maximum that any should leak is 100 microamps. PCs typically leak 60 microamps or less. That is 1.8 milliamps maximum. In other venues, an RCDs trips on 5 ma - because no appliances all grouped together should never leak even 5 milliamps.
That 100 milliamp RCD has detected a potentially serious human safety problem.
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
On Tue, 10 Nov 2015 23:44:01 +0000, westom

Where do you get 100uA from? A class1 piece of equipment to IEC 950 (Information Technology Equipment), a PC for example, can have up to 3.5mA of earth leakage current. Moreover an RCD will eventually trip if continuously subjected to a current imbalance of half its rated value, so 15mA will eventually trip an RCD. Given a worse case but compliant leakage it would require only 5 pieces of Class 1 (earthed) IT equipment to eventually trip a 30mA RCD.
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
replying to Peter Parry , westom wrote:

We design this stuff. Maybe 1 milliamp is acceptable in some undeveloped nations. But other standards demand well under 100 microamps. Furthermore, leakage that low is easy. Some venues must have numerous equipment on the same circuit that would trip at 5 milliamps. 3.5 mA leakage from any appliance is a serious design or manufacturing flaw. Especially when microamps are so easily achieved.
I have never seen a standard that permits a leakage that large. A PC leaking 3.5 ma would cause circuit tripouts in many nations - completely unacceptable when a computer must be designed for all world power systems. Those milliamps approach currents that can kill. In many venues, a 5 milliamp leakage would trip RCDs.
If a 100 milliamp RCD is tripping, then the building contains a serious human safety defect. Fix the defect. Many, instead, want to blame the RCD.
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
On 11/11/2015 16:44, westom wrote:

That is the most worrying statement someone who claims to be versed in this subject can ever make.
If you would kind enough to state who you design for, so I can make a special case of avoiding their equipment?
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload

HomeOwnersHub.com is a website for homeowners and building and maintenance pros. It is not affiliated with any of the manufacturers or service providers discussed here. All logos and trade names are the property of their respective owners.