Rcbo's

[Deleted member 9648]

In one of our school sites there are some IT suites with more PC's than the OP's spec on each RFC. Not sure on exact numbers but I suspect there are as many as 15-20 PC's on some,which run without problems. One large suite had around 20-30 PC's running from a dedicated DB with a 30ma main switch....cant recall it ever tripping.

 

[cliffed]

Yea no probs connecting cpc's & numbering them, the hassle were connecting the corresponding earths of the rcbo's.Reckon another seperate earth bar would be the answer.

 

[Deleted member 72666]

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.

Exactly!
I always use cable markers (partek ones I find the best) but still think some clown who next comes along to add a circuit or two will bugger it up and just connect them together even though there's a label warning them of the setup.

 

[Trevle]

Surely there wouldn't be a problem with say circuit 4 - lights sharing the no.4 earth terminal with circuit 2 - ring? If you're running out of terminal, just as long as the two from the ring aren't in the same terminal.

 

[Pete999]

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

If you are saying that then, you must be installing a lot of high integrity circuits, then at the the planning stage you should have taken the need for extra earth bars into account.
Realistically how many circuits with the need for HI earthing would be required in, say a small to medium sized office installation, more to the point how may Electricians do you know who actually employ this method, I was involved in a recent EICR as an adviser where the RFCs where just chucked in, no notice taken of the possible earth leakage possibilities.

 

[Deleted member 72666]

Yea no probs connecting cpc's & numbering them, the hassle were connecting the corresponding earths of the rcbo's.Reckon another seperate earth bar would be the answer.

I agree fully! When I asked you the questions I wasn't trying to be 'picky' I just wanted to know what everyone else does.

 

[Deleted member 72666]

In one of our school sites there are some IT suites with more PC's than the OP's spec on each RFC. Not sure on exact numbers but I suspect there are as many as 15-20 PC's on some,which run without problems. One large suite had around 20-30 PC's running from a dedicated DB with a 30ma main switch....cant recall it ever tripping.

Ha, ha, ha, I'd have been back to test the rcd when they were next on holiday!

 

[Flanders]

About 15 years ago we were guided 8 twin sockets not just due to earth leakage but due to the start up of those old monitors now we all use lcd which use a lot less power , i dont knowif the old monitors produced any earth leakage but i would of thought the lcd one don't produce any . And as said if as been designed for 15 sockets then thats down to the designer to worry about. Maybe pcs dont produce as much earth leakage as they did in the past .

 

[cliffed]

Very true,maybe it's the way forward .

 

[Martin Kerr]

Send an an RFI to the consultant ,asking how he would like to comply with the relevant regulation based on his DB selection?

 

[Pete999]

As long as you wire the circuits, be they Rings or Radials correctly as per OSG 7.5 and adhere to the rules therin, as well as OSG 6.15 you should be OK

 

[Martin Kerr]

As long as you wire the circuits, be they Rings or Radials correctly as per OSG 7.5 and adhere to the rules therin, as well as OSG 6.15 you should be OK

Can you refresh my memory to these points Pete, I Think the dog eat my copy ,few years back

 

[Pete999]

Can you refresh my memory to these points Pete, I Think the dog eat my copy ,few years back

Well 7.5 shows you how to wire the circuits and the reasons and 6.15 shows you what labels are required, nothing earth shattering (excuse the pun)

 

[cliffed]

What do you mean

 

[cliffed]

Send an an RFI to the consultant ,asking how he would like to comply with the relevant regulation based on his DB selection?

What do you mean?

 

[cliffed]

Thanks guys for the answer for above

 

[Martin Kerr]

If the number of earth terminals supplied within the DB , is not sufficient to comply with the recommendation of the high integrity earthing .ask him how he would like them terminated?

 

[Pete999]

If the number of earth terminals supplied within the DB , is not sufficient to comply with the recommendation of the high integrity earthing .ask him how he would like them terminated?

If you have to ask him that question then he aint done his sums right.

 

[Martin Kerr]

Well 7.5 shows you how to wire the circuits and the reasons and 6.15 shows you what labels are required, nothing earth shattering (excuse the pun)

Don't go spilling any of that red wine over the OSG Pete

 

[Pete999]

Don't go spilling any of that red wine over the OSG Pete

All gone Martin she rations me now