Discuss 30m/A protection on outside sockets in the Electrical Wiring, Theories and Regulations area at ElectriciansForums.net

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As I'm aware all outside sockets must have at least 30m/A RCD protection . However....
The DB this socket is fed from has a 100m/A main RCD (the socket is off a 10A MCB). So it doesn't comply.
But....this DB is a submains and is fed from another DB which DOES have a 30m/A main RCD. So does this comply with the regs or not? I understand that if there was a fault it would most likely trip the 30m/A RCD first , meaning everything would trip, so there is no discrimination. But what would you recommend putting on the test sheet (recommendations sheet). Cheers guys
 
Exactly . It's a complete waste of time. Also if there was a problem with that socket it would trip out the whole installation. Yes it is EIC. Iv put in the recommendations that there is no discrimination between the two RCDs and recommend changing 100m/A RCD to a 30m/A .
 
Exactly . It's a complete waste of time. Also if there was a problem with that socket it would trip out the whole installation. Yes it is EIC. Iv put in the recommendations that there is no discrimination between the two RCDs and recommend changing 100m/A RCD to a 30m/A .
If you change the 100mA to a 30mA you will still have no discrimination (or even less discrimination).
Preferably the supply to the socket DB should be taken from a non RCD protected way (cable run allowing) and the 100mA RCD changed to a 30mA RCD or the 10A MCB changed to an RCBO to provide circuit separation.

Without knowing the whole layout a recommendation is difficult to give but main RCDs are a bit of a problem now with avoidance of nuisance tripping.
 
If you change the 100mA to a 30mA you will still have no discrimination (or even less discrimination).
Preferably the supply to the socket DB should be taken from a non RCD protected way (cable run allowing) and the 100mA RCD changed to a 30mA RCD or the 10A MCB changed to an RCBO to provide circuit separation.

Without knowing the whole layout a recommendation is difficult to give but main RCDs are a bit of a problem now with avoidance of nuisance tripping.

You don't have discrimination anyway as the 100mA RCD is supplied from a 30mA RCD then the 30mA will go before the 100mA
 
You don't have discrimination anyway as the 100mA RCD is supplied from a 30mA RCD then the 30mA will go before the 100mA


Not always. It can be a guess as to which one will go first. This has been covered before in other threads and people have found when doing the rcd auto test, the 100ma rcd would trip before the 30ma. It is preferably to use a time delayed rcd to achieve discrimination.


Jay
 
I agree. In an ideal world the submains should be supplied by a DB without an RCD. But rerouting the circuit from another DB is not an option unfortunatley.
Therefore I think the easiest thing to do is recommend changing the MCB (which feeds the socket outlet) to a RCBO.
P.s Have tried an RCD test and the 30m/A RCD (mains) trips out before the 100m/A RCD (submains)
 
The regs are not retrospective, there may be nothing wrong with the installation, other than it is not to current standards. If it to an earlier standard, and it all tests out OK, then you have no problems. You may point out to the client any non conformances to current standards, but this doesnt make it dangerous, nor is it a viable reason to make them spend money.

You need to give a lot more info about the installation, such as supply type and so on, you can then get some constructive feedback about the current set up.

Cheers...............Howard
 
As it stands, the socket-outlets are protected by a 30mA RCD in the first DB.
As it stands, the 100mA rcd at the second DB is a complete waste of time, as would be installing a 30mA RCBO for the socket-outlet circuit.
There are two options available.
Either junk the 100mA RCD for a double pole switch, or re-wire the installation correctly.
Unless you can argue that having the 30mA RCD where it is, is less safe than replacing it with a double pole switch, you are stuck with keeping the 30mA RCD.
 
Exactly . It's a complete waste of time. Also if there was a problem with that socket it would trip out the whole installation. Yes it is EIC. Iv put in the recommendations that there is no discrimination between the two RCDs and recommend changing 100m/A RCD to a 30m/A .

I agree. In an ideal world the submains should be supplied by a DB without an RCD. But rerouting the circuit from another DB is not an option unfortunatley.
Therefore I think the easiest thing to do is recommend changing the MCB (which feeds the socket outlet) to a RCBO.
P.s Have tried an RCD test and the 30m/A RCD (mains) trips out before the 100m/A RCD (submains)

This all depends on the customer. He wants a socket installed, end of!
Unless you’re trying to rip the customer off. (I shouldn’t suggest such things, but with some new members it seems to be prevalent).


The protection is there so why on earth would he pay for you ripping the system apart for you own satisfaction?
A new 80A isolator and has been suggested an RCBO, isn’t going to make a blind bit of difference to him. He’s still got 30mA protection.
 
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What I am testing isn't a house. I'm testing fibre optic cabinets for Virgin Media. There are two cabinets side by side , the mains cabinet has a 2 way DB (Circuit 1-feeds cat5 equipment in this cab) (circuit 2 feeds the cabinet nextdoor) . The Submains cabinet also has a 2 way DB. (circuit 1-feeds telecoms equipment in this cabinet) (circuit 2 feeds a 2 pin socket which is part of the DB).

I'm actually wondering now if this socket needs 30m/A protection? Although it's outdoors, it's actually inside a cabinet. It's a 4A test socket attached to the side of the DB.

What do you think?
 

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