various questions

[welder8uk]

I am at the info gathering stage at the moment (intend to do the work approx 2 mnths time) and have read quite a lot of the threads so far for the background info.

Background, I am refurbishing an old water mill which was renovated approx 1975. Although the wiring is in very good condition its a bit untidy and doesn't seem particularly well planned out. It is run off 3 old wylex boards, situated next to each other. I am pretty sure I know what I want to do, but I would like a bit of advice. The building is currently split into two, the other side requires complete refurbishment including wiring.

My background is electrical engineering (however I haven't been a practising engineer for about 8years) - and this was industrial electrics not domestic.

The overall aim is to:

- install a 16a welding socket into the garage, this is also to double up as a generator infeed for the house electrics in the event of power failure
- remove the 3 wylex boards and replace with one CU
- rewire the other side of the building with its own CU,

The house is, as far as I can tell, a TT system, but there isn't an RCD - yet.


Work intended (probably in order, this is the easiest/ safest way it would be for me), and council permission that I think I need:

1. Install a isolator between the meter and wylex boards, including henleys. The old boards will then be reconnected to the henleys with 25mm tails (they are currently a lot thinner). I don't believe that this is part P covered

2. Install a 4mm SWA cable through a fuseable isolator to the garage, feeding from the henleys. This will then act as a welding socket, and (if I isolate the henleys from the grid) I can connect a generator up to the house boards (if this makes sense). I don't believe that this is part P covered.

3. Change the old wilex boards to a new CU. crimping the cables to extend where necessary. I don't believe that this is part P covered

The next bit I think is part P covered, as it will involve wiring a kitchen up, (or what will be a kitchen when it is finished). I intend to notify the council and then do the work ready for their inspection before it is powered up.
4. run 2 single 25mm tails from the henleys to the location of the CU approx 15m away. Install CU and run necessary lighting and ring mains ect.


Questions:
- is the above realistic

- the new CU will have RCD's in then, will I still require an RCD on the incomer - ie between the meter and the henleys (I don't really want to put one there)..

- what size earth will I require for the new CU, I was planning on using a 16mm. Not sure what size the earth cable is to the earth spike

- I need an isolator for any tails over 3m, will the isolator between the meter and the henleys be acceptable, or does the new CU need its own isolator.

- given the untidiness of the 3 wylex boards i am expecting to find some unusual rings in place, can I
- if I find a two socket rings that cover the same area (assuming they are both 2.5mm, can I connect 2 rings to the same fuse. I would like to put all the downstairs sockets on the same fuse, downstair lights on a single different fuse ect.
- if I find several spurs off the wilex boards, using the same size cable, is it acceptable to connect more than one spur to a single fuse


I have some other digging about to do with regards to info about the current system, I want to know exactly what I have before I start to pull it apart.

Thanks for any advice, I know once I plan it out better I will probably have some more questions

Steve

 

[mapj1]

I'd suggest that at least in spirit, the writers of Part P expected CU changes to be notified to the building control office in advance, best phone your local council and ask if the legality bothers you..
However, putting that to one side. You need a single clearly marked main islolator that is double insulated if it is not itself an over-arching RCD.
All circuits must be RCD protected, but only sockets must be on a 30mA RCD, the rest could bo on soemtihng larger if you prefer. This can be achiecev either by multiple RCDS, one poer circuit, or grouped, as the mood required.

 

[ban-all-sheds]

- install a 16a welding socket into the garage, this is also to double up as a generator infeed for the house electrics in the event of power failure

In one use or another the gender of the plug or socket will be dangerously wrong.

Also, I'm not an expert on standby generators, but I don't think this is the accepted way of doing it.

1. ...I don't believe that this is part P covered

Oh yes it is.

2. ..I don't believe that this is part P covered.

Oh yes it is.

3. ... I don't believe that this is part P covered

Oh yes it is.

The next bit I think is part P covered, as it will involve wiring a kitchen up, (or what will be a kitchen when it is finished). I intend to notify the council and then do the work ready for their inspection before it is powered up.

They may want to inspect more than once. You'll have to be guided by them.

- the new CU will have RCD's in then, will I still require an RCD on the incomer - ie between the meter and the henleys (I don't really want to put one there)..

Everything needs RCD protection. Multiple RCDs/RCBOs protecting segments of the installation rather than 1 RCD for the whole lot is better.

- what size earth will I require for the new CU, I was planning on using a 16mm. Not sure what size the earth cable is to the earth spike

See On-Site Guide p 29. If you don't have an OSG, buy one immediately.

- I need an isolator for any tails over 3m, will the isolator between the meter and the henleys be acceptable, or does the new CU need its own isolator.

You'll probably need a switchfuse rather than just an isolator. Isolators in series so that you can isolate on a per-CU basis as well is better than only 1 for the whole installation.

- if I find a two socket rings that cover the same area (assuming they are both 2.5mm, can I connect 2 rings to the same fuse.

You shouldn't do that.

I would like to put all the downstairs sockets on the same fuse, downstair lights on a single different fuse ect.

Although simplicity has its appeal, multiple circuits can be better for load distribution, fault discrimination and convenience, but obviously need careful labelling.

- if I find several spurs off the wilex boards, using the same size cable, is it acceptable to connect more than one spur to a single fuse

By spur I assume you mean radial? Again you shouldn't do this, and ditto comments about multiple circuits.

 

[welder8uk]

Thanks for the advice, just the sort of stuff I was looking for. AS i said I am at the fact finding stage, to identify what I can and cannot do re paperwork and the actual installation.

Looks like the generrator/ welding socket is going to be a welding socket only

Though I had every book with the words 16th Ed written on them, I havent got the OSG, just ordered it from Amazon.

I realise I was streaching the definition a bit, I was using the Govmnt own guidlines from http://www.odpm.gov.uk/stellent/groups/odpm_buildreg/documents/page/odpm_breg_033480.hcsp

A: You do not need to tell your local authority's Building Control Department about:

repairs, replacements and maintenance work; or
extra power points or lighting points or other alterations to existing circuits (except in a kitchen or bathroom, or outdoors).
You need to tell them about most other work.

I was reading this as repair, replacement and maintenance of the existing installation

Ill give the OSG a good read when it comes.

Thanks


Steve