RCD's in a commercial environment

[brizospark]

I am carrying out PIR's on a number of commercial installs

I find that even with intalls less than 2 years old, the installers have failed to protect many relevant circuits with RCD.

The type of commercial property I am testing is the type with a lot of computers, TV's, sockets for cleaners, water heaters, etc., surely these should be covered by RCD's

I know in BRB it states that it is OK not to use an RCD on socket outlets when the equipment plugged in to the socket will be used by a "trained" person, but I doubt that you could qualify someone sitting behind a computer screen, or a cleaner using a hoover or floor buffer as "trained"

What are your opinions on RCD protection in a commercial environment? I know that some commercial owners regard RCD's as nuisance trippers but at the end of the day if there aint nothing wrong with the circuit, the RCD won't trip

 

[malcolmsanford]

Well I said this before I totally agree with you, I also don't regard an office full of IT workers as either skilled or instructed. Though that is where I think a lot try to get away with it on the instructed front.

I know a lot of Sparks don't like using RCD for IT equipment because of Equipment with High protective condutor currents. That to me is poor circuit design. The old 16th was a lot better informed on this and the old rule of thumb would be a maximum of 8 units on one 30mA RCD. The old design criteria would be 25% of the 30mA I delta N so an protective current of 8-10mA.

I agree now that in a lot of offices there are more personal items phone chargers, things like that, but on the other hand there is less actual computer equipment gone are towers and screens ,now it's hot desking and laptops.

As far as the PIR I doubt if you could actually code it, and it you did it would have to be a 4. Though suprised your actually doing a PIR on a system less than 2 years old unless it's change of use or ownership.

 

[brizospark]

Client had a load of shops needing PIR's so decided to get the whole lot done, including the newly wired ones so they are now due at the same time.

I would have to say that an install wired to 17th could put down code 2 for absence of RCD's

 

[IQ Electrical]

The current design advice is a maximum background earth leakage of 15mA per 30mA device.

The IET technical department explained the 'installation under the control of instructed....." as primarily a domestic installation rule.

The commercial installation is more likely to be worked on by a competent person rather than a DIYer and therefore often sneaks into this instructed/skilled rule.

Another thing to remember is that your PIR compares an installation to the requirements of the current edition of BS7671 and the installed date should have no effect whatsoever on any codes applied.

Read this: http://www.esc.org.uk/pdfs/business-and-community/electrical-industry/BPG4_08.pdf

 

[malcolmsanford]

I would be very wary to try and dis prove a commerical enviroment is not under the supervision of a skilled or Instructed person. It is generally recognised that domestic situations are not considered this.

If you code it a 2 then your saying the installation is unsatifactory and your PIR will be refelcting this. IMO if you are going to code it code it a 4 , and if you want send in a cover letter outlining your concerns and some suggestions to make the installation safer. If it were my PIR then I would not code it at all if the disconnection times were met for the protection devices.

This sounds like a nice little contract you have, and honestly in the real world you have to sometimes remember the BRB is a guide and not law.

 

[brizospark]

I would be very wary to try and dis prove a commerical enviroment is not under the supervision of a skilled or Instructed person. It is generally recognised that domestic situations are not considered this.

If you code it a 2 then your saying the installation is unsatifactory and your PIR will be refelcting this. IMO if you are going to code it code it a 4 , and if you want send in a cover letter outlining your concerns and some suggestions to make the installation safer. If it were my PIR then I would not code it at all if the disconnection times were met for the protection devices.

This sounds like a nice little contract you have, and honestly in the real world you have to sometimes remember the BRB is a guide and not law.

True, it is not the law, but it would only improve the installation to have the socket outlets RCD protected. For the sake of installing a few RCBO's it would surely provide the owner with piece of mind when thinking about not only his employees but also the building itself. Like I said an RCD will only trip when there is a fault with the circuit.

The way I see it is this - Mary Smith is in the house hoovering in her house, the socket in the house should be RCD protected, she then goes to work and hoovers up at her cleaning job, all of a sudden the socket does not require RCD protection as she is a "trained" person.

Where is the sense in this?