High integrity earthing, it equipment and RCD's

[Neil Holdsworth]

I've been asked to install additional sockets within dado trunking in a small office. It's currently being used for one computer but is going to have quite a few more. The problem is in somebody's wisdom they have fitted a 30ma trip upfront to protect the DB. Cables are run in mini trunking from the db to the dado trunking. Some of the sockets have two earth terminal in the dado and some don't, 

My proposal was to replace the RCD main switch to a normal switch. Replace any of the sockets not with dual earth terminals.

Can anyone see a way round of not fitting an rcbo to these sockets as with all sockets requiring an rcd im worried about earth leakage tripping the rcbo. There isn't enough room in the mini trunking to add an additional circuit.

Thanks Neil

 

[steptoe]

Well, you will have to install bigger trunking then.

 

[Lurch]

How many computers? You need quite a few to cause any real issues. I regularly see offices with 10 PC's on a single RCD with no issues. Not saying it is best practice, but there isn't usually an issue in having multiple computers on a single RCD.

Is it actually wired for high integrity earthing (as in dual earths run to each point, correct sockets fitted (not just any old random socket with 2 earth terminals))?

If you really need to install another circuit or 2 install some larger trunking.

 

[Neil Holdsworth]

It's three towers and 6 monitors plus a battery back up, so not a huge amount of equipment. But with am rcd upfront i don't want to take the risk that the whole board switches off. The original installation doesn't look like its been installed with any competency. DB is a right mess and the way the building has been wired  and designed just has the look of someone didn't have a clue. There are some dual earth terminal sockets but only one terminal has been used in each of them.

 

[Lurch]

It's three towers and 6 monitors plus a battery back up,

I've got more than that in my dining room. You are being over cautious. There does not need to be any extra circuits brought in for this. You're right in that the upfront RCD isn't ideal, but I wouldn;t be changing it just because they are plugging an extra 2 computers in. Have you actually tested anything, is there any existing leakage?

There are some dual earth terminal sockets but only one terminal has been used in each of them.

That doesn't answer the question. Are they high integrity sockets? Do you know what high integrity earthing actually is?

the way the building has been wired  and designed just has the look of someone didn't have a clue.

It doesn't sound like it is going to get any better. You are randomly looking at changing sockets even though you have no idea what you are doing. You are in over your head here.