Rcbo's

[cliffed]

Just finished installing power sockets in It suites at a school.
All protected by 30 ma rcbo's ,circuits specified by electrical consultants,15 2 gang skts on each circuit.All working & no trip outs.
My reckoning was about 7 2 gang skts per circuit,what's your feelings on this.
Have I gotta change my reasoning on these circuits & follow suit.

 

[Deleted member 72666]

That's far more than I would dare to put on each rcbo, out of interest how many cct's did you install?

 

[Deleted member 72666]

Oh, and were the circuits rings or radials?

 

[Leesparkykent]

I normally follow a rule of thumb of no more than 8 computers/work stations per circuit.

 

[Andy78]

A good idea would be to measure the actual earth leakage on the circuits with all sockets in use. I would be interested to know the results.

I used to do a lot of IT room installs for a previous company and the local authority spec was 6 double sockets per 32A ring circuit. This was based on one workstation (one pc and one monitor) per double outlet. I always thought this was a bit on the cautious side.

 

[cliffed]

Oh, and were the circuits rings or radials?

Ring main circuits,2 for each classroom,6 classrooms in total.In each room total of 30 2 gang sockets.

 

[Deleted member 72666]

Ring main circuits,2 for each classroom,6 classrooms in total

Were they all fed from the same dist. board and if so how did you accommodate all the cpc's given that they have to be kept seperate?

 

[Martin Kerr]

Why are you so concerned ?, just follow the consultants design ,that's what he is getting paid for.
Just sign the installation section of the cert

 

[Pete999]

Oh, and were the circuits rings or radials?

Beat me to it Mate

 

[Pete999]

Were they all fed from the same dist. board and if so how did you accommodate all the cpc's given that they have to be kept seperate?

Pardon, kept separate?

 

[Leesparkykent]

Pardon, kept separate?

High integrity earthing so the cpc's will be in separate terminals in each socket and in the DB.

 

[Deleted member 72666]

Cpc's for high protective conductors currents.

 

[Deleted member 72666]

Thanks Lee!

 

[Pete999]

High integrity earthing so the cpc's will be in separate terminals in each socket and in the DB.

Right so how is that going to be a problem?

 

[Deleted member 72666]

Depending on the size of board and number of circuits you can find yourself fast running out of earth terminals.
.... And it throws them out of sync when every other terminal is in the correct termination number wise.

 

[cliffed]

Depending on the size of board and number of circuits you can find yourself fast running out of earth terminals.
.... And it throws them out of sync when every other terminal is in the correct termination number wise.

Not a problem using 18 way TPN DB,all earths connected correctly for installation

 

[Leesparkykent]

Right so how is that going to be a problem?

Its not really if the boards big enough you just end up with loads of spare ways that cant be used.

 

[Pete999]

Depending on the size of board and number of circuits you can find yourself fast running out of earth terminals.
.... And it throws them out of sync when every other terminal is in the correct termination number wise.

Carp just take your time jobs a good un, two earth terminals at the DB for either a Ring or Radial final circuit nothing difficult or out of the ordinary for a good Sparky, although it doesn't apply to the Domestic Installers.

 

[Deleted member 72666]

Not a problem using 18 way TPN DB,all earths connected correctly for installation

I recently did a small(ish) office which had amongst other things 3 radial cct's with high integrity earthing fed from a 10 way single phase board. I installed an extra earth bar to accommodate the extra cpc's but didn't use it in the end as I found a different way of doing it and still achieve compliance with the regs.

 

[Martin Kerr]

I think this is where the Regs trips it self up in situations like this, apart from a few additional terminals for main earths, bonding etc, no standard DB can fulfill the requirements for high integratity earthing comprising more than a couple of circuits and unless the additional earth conductors are cable I'd, it would make it very confusing for the next person coming along at a later date.