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Thanks for the reply, had a more detailed read of the methods and based on what it says in the green bible it's reference method c.

I have always been told/understood that the reference method for cables buried in plaster was reference method c (clipped direct), however I have seen reference made to reference method a (enclosed in conduit in an insulated wall).  Does anybody have a definitive answer please?

I am aware that Band I (ELV) and Band II (LV) circuits should be kept segregated. My understanding of the reason behind this is firstly to reduce noise interference on data cables as well as control, alarm and fire circuits. Secondly, to ensure that no emf is induced into the Band I (ELV)...

The haze is clearing a little now, so the first column is the energy limiting class 3 device rating as apposed to its rated current In is that correct?

Okay so had a read through and makes a little more sense, but going back to my original post, the table on page 120 refers to cpc size being a min size of 2.5mm2 for MCB's <= 16A. So if I was installing a lighting circuit in a house in general the cpc would be 1.5mm2 which contravenes this...

Cheers will have a read thxs

Just read page 120 again and yes it is the energy limiting class I need explaining please?

It was from the green OSG page 120 and its a table which details min cpc size in relation to the energy let through rating of the protective device?

I know that MCB's are grade with an energy let through rating of 1, 2 or 3 and 3 being the highest. I also know that it relates to the sizing of the cpc. However that is about where my understanding ends, I have read a few threads and documents, but still having trouble getting my head around...

Re-posting thread

Thanks for that, really appreciated!!

Thanks for clearing that up, saw the bit about IP in the regs and would need to increase to IPX5 with jets of water. So I presume that you would just connect the 1.5 T&E switch return from the junction box to the first downlighters connection blocks and then loop to the next?

Thanks Guy's, just one more quick question. If you use a 230v downlighter I presume then that you don't need a transformer? It just that me an a fellow student seem to be disagreeing on this one, as I don't think you would need one as you are not dropping the voltage.

Can I ask a quick question, if you install down lighters in zone 1 can they be 230v providing the lighting circuit is protected by a RCD and the down lighters are suitable for zone 1 and are at least IPX4?

Re-posting this thread

Re-posting this thread

This does seem to be a very grey area as it depends on who you speak to as to whether you do or don't need detectors!!

Thxs Andy, are you referring to both smoke and heat detectors?

I have had a quick read of part b and it only seems to state the requirements for smoke and heat detectors for new builds. So I prosume then that for a rewire you wouldnt need to install them? But everybody I ha e spoken to says that you do? I appreciate that part b is law, but was wandering...

I know that in line with part b of the building regs when rewiring a house you need to install smoke alarms upstairs and down and a heat detector in the kitchen. However what I can not seem to find is anything to this fact in BS7671 or the OSG. I have seen it in the red OSG, but nothing in the...