add to existing or create a new circuit?

[rustyh]

Evening All,

I'm looking to add some sockets in to my hall way, they will be located under the stairs, so I plan to use conduit.

Pretty basic question, would you link this up to the lower flow ring mains (IE: take one end of the existing lower ring out of the CU and then loop it through the hall way sockets), or would you just create a new circuit (maybe a radial) and hook it up to a 16A MCB??

CU is RCD protected as well for added info

 

[flameport]

Either is fine, whichever is easiest.

Adding a new circuit is notifiable, so in theory the 16A MCB option would need to be notified.
In the real world, no one will bother or care.

 

[PrenticeBoyofDerry]

You could do either.
Problem one: New circuits require building control approval and notification
Problem two: New sockets require 30mA RCD protection. you may not have this on your circuit or at the fuse board.

 

[JohnW2]

You could do either. ... Problem one: New circuits require building control approval and notification

Agreed.

Problem two: New sockets require 30mA RCD protection. you may not have this on your circuit or at the fuse board.

CU is RCD protected as well for added info

Kind Regards, John

 

[rustyh]

Thanks for the replies

There are two 30mA RCD that feed 6 MCBs each

 

[PrenticeBoyofDerry]

Problem two: New sockets require 30mA RCD protection. you may not have this on your circuit or at the fuse board.

CU is RCD protected as well for added info

I have often come across consumer units that have RCD protection at the board but does not cover all circuits, including socket circuits, I was suggesting that it be confirmed.

 

[PrenticeBoyofDerry]

Thanks for the replies

There are two 30mA RCD that feed 6 MCBs each

And if you isolate or press test button on them, does the socket circuit you intend to extend lose power?

Also could you confirm that the RCD is functioning within the requirements expected for a domestic property?

 

[JohnW2]

Also could you confirm that the RCD is functioning within the requirements expected for a domestic property?

These semi-cryptic rhetorical questions seem to be becoming increasingly common around here, and I suspect that they confuse and/or are 'lost on' a high proportion of those OPs to whom they are directed.

If you wish to (correctly) point out to an OP that they almost certainly do not have the means to properly test the functioning of an RCD (as theoretically required by the regs when work is done on an associated circuit), then, FWIW, I personally feel that it would be far more straightforward, 'honest' and helpful to simply say that!

Kind Regards, John

 

[securespark]

It would be wise to get a professional to confirm that the RCD is functioning within the requirements expected for a domestic property.

 

[JohnW2]

It would be wise to get a professional to confirm that the RCD is functioning within the requirements expected for a domestic property.

Exactly. FWIW, my personal view is that it is always best to speak with a non-forked tongue - i.e. say what one actually wants to say, rather than hope that people will be able to decrypt what one has actually said!

Kind Regards, John

 

[PrenticeBoyofDerry]

It would be wise to get a professional electrician that has the correctly calibrated equipment and the knowledge and skill to competently complete this task to confirm that the RCD is functioning within the requirements expected for a domestic property as outlined by BS7671:2008

or just tell them to crack on with it as no one really gives a ****! Oh flamepot has already done that and it seems you lot are more concerned that I mention the RCD requires to be confirmed to be functioning correctly!

 

[JohnW2]

It would be wise to get a professional electrician that has the correctly calibrated equipment and the knowledge and skill to competently complete this task to confirm that the RCD is functioning within the requirements expected for a domestic property as outlined by BS7671:2008

If you prefer (that gives even more explanation), but I think that secure's previous suggestion as to what you might have written would probably be adequate.

... it seems you lot are more concerned that I mention the RCD requires to be confirmed to be functioning correctly!

I cant speak for all of "you lot", but I think that's very unfair in terms of what I wrote/suggested. As I wrote, I would have absolutely no problem with your "mentioning that the RCD requires to be confirmed to be functioning correctly". I was merely commenting on the fact that you did not actually write that but, rather, you asked a semi-cryptic question which the OP may well not have understood. You knew what you were getting at, and I knew what you were getting at, but the OP very probably didn't.

Kind Regards, John

 

[PrenticeBoyofDerry]

You knew what you were getting at, and I knew what you were getting at, but the OP very probably didn't.

That was my intention, so then the OP hopefully is taking note and responds in an inquisitive manner and can be informed further. Or they just ignore what I have posted, please themselves, so I then go and help someone who can be bothered and does care! about the requirements of BS7671/Part P and the importance that electrical installation must not be considered a plug-in and play project.

I have been trying to prevent long winded explanation on reasoning behind safety and the need for testing, unless the OP actually shows any interest in being bothered!

And it seems that once testing was mentioned, the OP has for one reason or another retreated from the their thread.

 

[ericmark]

On the RCD point a proper tester measures the time the push the button test does not but both test that with an earth leakage that the device will operate.

The RCD we hope operates before we touch the faulty device and in that case the time is not important. Yes drilling into a cable one needs the device to operate within the 40ms laid down but in the main they trip when for example water has been split on something and even one second would be fast enough.

As to new circuit and Part P it's back to defining a circuit. The supply could be regarded as being split into two circuits supplied by RCD1 and RCD2. The MCB's are no different to FCU's and since use of latter is not considered as new circuit under Part P neither can use of the former be considered as being forming a new circuit.

Yes BS7671 would consider a FCU as forming a new circuit. But although Part P says that one way to comply is to follow BS7671 it would seem it would require a court case to be fought and a president to be set before anyone can work out what the law requires.

At the end of the day it is near impossible for any DIY person to do any electrical work and comply with BS7671 so since this is a DIY forum what is the point in telling the DIY'er that he can't do something what is more important is to show them how to do it as safe as they can.

Advising them to use one of these

at £35 may be they will use it. But advise them to use one of these

at £450 and your really wasting your time.

So come on chaps lets get real.

 

[JohnW2]

You knew what you were getting at, and I knew what you were getting at, but the OP very probably didn't.

That was my intention, so then the OP hopefully is taking note and responds in an inquisitive manner and can be informed further.

If you're saying that you deliberately wrote something which you didn't think the OP would understand, the hope that the OP would then question you about it, then, as I've said, I personally don't think that is the ideal or correct approach. As I've said, if one has an important point that one wishes to make (e.g. that the RCD should be properly tested), then I personally feel that the point should be made as clearly as possible - and certainly not 'deliberately unclearly'!

Our ideas about communication clearly differ, so we may just have to disagree about this!

Kind Regards, John