Re-wiring and Part P etc
Brett Jackson
Hi All,
I've not done any serious wiring now for a few years the last time being
when I re-wired by previous house prior to all this Part P business,
anyway now I've moved and I need to do it all again...
First thing to go is the fuse box. I can't seem to find any clear
guidance as to how I should utilise the 2 RCD's that you get with a
'17th edition' CU. There also seems to be some conflicting info (or
more probably some misunderstanding on my part) on the uk.d-i-y wiki
regarding what circuits should be RCD protected. It reads like 17th ed.
introduces some more stringent directives as to the protection of
circuits by RCD where T&E and other unprotected cables are buried in
walls below a certain depth, yet there is a suggestion that lighting and
some other circuits should remain unprotected. So, how would I arrange
my CU wrt the 2 RCD's and un-RCD'd circuits? I'm going to do the
re-wire stage by stage as I re-decorate each room, so I'll probably end
up with a couple of lighting circuits and half a dozen radial circuits
(one per room) for the sockets, plus a ring for the kitchen, CH, oven,
hob, garage etc.
I guess I need to read up and understand the full extent of the
applicable differences between 16th ed and 17th. Are there any
recommendations for a good book to cover the subject that doesn't me to
call in an electrician at every other turn?
There seems to be quite an emphasis on testing circuits after
installation, but I'm unsure whether this is necessary where I know my
workmanship is good and the circuits are simple, and there is simple
continuity testing I can do with a multimeter. Anyway I'm keen to do
things properly so I'd be interested to hear what people's views are on
this and assuming I really do need to do proper testing (I think I do)
how can I do this without forking out hundreds for testing kit?
Finally what's the current state of play with Part P and building
control? I've had a good look through recent posts and there doesn't
seem to be much discussion on the subject so I'm not sure where the
DIY'er currently stands with this? My local authority is Leeds if
anyone's familiar with their processes...
Apologies for the long post, and thanks in advance...
Owain
> First thing to go is the fuse box. I can't seem to find any clear
> guidance as to how I should utilise the 2 RCD's that you get with a
> '17th edition' CU. There also seems to be some conflicting info (or
> more probably some misunderstanding on my part) on the uk.d-i-y wiki
> regarding what circuits should be RCD protected. It reads like 17th ed.
> introduces some more stringent directives as to the protection of
> circuits by RCD where T&E and other unprotected cables are buried in
> walls below a certain depth, yet there is a suggestion that lighting and
> some other circuits should remain unprotected. So, how would I arrange
> my CU wrt the 2 RCD's and un-RCD'd circuits?
You don't have any un-RCD'd circuits. The CU is split into two halves,
and each half has an RCD. The idea is the whole house doesn't go off
when an RCD trips. It's still a bit of an kludge compared with having
individual RCBOs (combined MCB + RCD) for each individual circuit.
Try to split the lighting circuits over the 2 RCDs so you don't lose
all lights at once.
> I'm going to do the
> re-wire stage by stage as I re-decorate each room, so I'll probably end
> up with a couple of lighting circuits and half a dozen radial circuits
> (one per room) for the sockets, plus a ring for the kitchen, CH, oven,
> hob, garage etc.
A radial for each room and you will need either a large CU or have
some rooms without sockets! And you have a choice of using 2.5mm cable
and only having 20A on a circuit, or having to use 4mm cable to get
32A on a circuit.
Hob will usually require a dedicated cooker circuit. Single oven might
be less than 13A, but better placed on a cooker circuit IMO.
> I guess I need to read up and understand the full extent of the
> applicable differences between 16th ed and 17th.
Not *much* difference apart from RCDing everything unless you use a
limited range of cable methods, and if you do RCD everything you no
longer need equipotential bonding in bathrooms. You still do need main
equipotential bonding though.
> There seems to be quite an emphasis on testing circuits after
> installation, but I'm unsure whether this is necessary where I know my
> workmanship is good and the circuits are simple, and there is simple
> continuity testing I can do with a multimeter. Anyway I'm keen to do
> things properly so I'd be interested to hear what people's views are on
> this and assuming I really do need to do proper testing (I think I do)
> how can I do this without forking out hundreds for testing kit?
A multimeter will not test insulation or continuity to the required
standard, but you can hire a 17th edition tester for a week/weekend
fairly cheaply (~£100)
> Finally what's the current state of play with Part P and building
> control? I've had a good look through recent posts and there doesn't
> seem to be much discussion on the subject so I'm not sure where the
> DIY'er currently stands with this? My local authority is Leeds if
> anyone's familiar with their processes...
If you are DIYing it you are supposed to make a building regs
application for the work. The local authority is then supposed to do
any inspection and testing they want to do, and not charge you extra
for this. However, not all authorities are as co-operative as others.
Owain
Dave Liquorice
> Try to split the lighting circuits over the 2 RCDs so you don't lose
> all lights at once.
Might be wise to have the downstairs lights fed via the RCD that
protects the upstairs ring and vice versa. So if some one does do
somthing to trip the RCD they don't get plunged into darkness as
well. Of course some one somewhere else does... 6 of one half a dozen
of the other. RCBO's avoid this...
--
Cheers
Dave.
Andrew Gabriel
Owain <spuorg...@gowanhill.com> writes:
> You don't have any un-RCD'd circuits. The CU is split into two halves,
> and each half has an RCD. The idea is the whole house doesn't go off
> when an RCD trips. It's still a bit of an kludge compared with having
> individual RCBOs (combined MCB + RCD) for each individual circuit.
If you are doing this yourself, look at using some of the money
you're saving to provide RCBO's rather than the 17th ed kludge.
> Try to split the lighting circuits over the 2 RCDs so you don't lose
> all lights at once.
--
Andrew Gabriel
[email address is not usable -- followup in the newsgroup]
mick
<snip>
>
> I guess I need to read up and understand the full extent of the
> applicable differences between 16th ed and 17th. Are there any
> recommendations for a good book to cover the subject that doesn't me to
> call in an electrician at every other turn?
>
If you check out part P then you'll find that there is very little that
you *can* legally do now without being registered.
You can't install any new circuits.
You can't modify or change the CU.
You *can* change a socket - even from single to double! :-)
You can't change or install a light fitting in a shower.
...and lots of other stuff.
> There seems to be quite an emphasis on testing circuits after
> installation, but I'm unsure whether this is necessary where I know my
> workmanship is good and the circuits are simple, and there is simple
> continuity testing I can do with a multimeter. Anyway I'm keen to do
> things properly so I'd be interested to hear what people's views are on
> this and assuming I really do need to do proper testing (I think I do)
> how can I do this without forking out hundreds for testing kit?
>
You're right. There is a lot of emphasis on testing. In order to get a
test certificate this has to be carried out - and you are very unlikely
to find any 'leccy who will test and issue an Electrical Installation
Certificate (the one that you need) where someone else has done the work.
Nowadays you should really have that certificate if you come to sell the
house. :-(
Without the right (calibrated) gear there is no way that you can test an
installation and issue a test certificate. Even the test certs are serial
numbered and traceable back to the issuer so you can't scrounge a blank.
They won't photocopy either! (Just in case anyone wonders how I know
this, I type up test certs for an electrical contracting firm as part of
my job.)
--
Mick (Working in a M$-free zone!)
Web: http://www.nascom.info
Filtering everything posted from googlegroups to kill spam.
Mike Harrison
>A multimeter will not test insulation or continuity to the required
>standard, but you can hire a 17th edition tester for a week/weekend
>fairly cheaply (~�100)
If you are using all new parts/cable and are competent at wiring, the probablility of a fault that
would only be detectable by a 'proper' tester is negligible.
For a makeshift insulation test, a low-range AC current meter across an open breaker should show up
anything serious..
Continuity test at high currents could also be improvised with a little imagination.
JimK
> You're right. There is a lot of emphasis on testing. In order to get a
> test certificate this has to be carried out - and you are very unlikely
> to find any 'leccy who will test and issue an Electrical Installation
> Certificate (the one that you need) where someone else has done the work.
> Nowadays you should really have that certificate if you come to sell the
> house. :-(
>
> Without the right (calibrated) gear there is no way that you can test an
> installation and issue a test certificate. Even the test certs are serial
> numbered and traceable back to the issuer so you can't scrounge a blank.
> They won't photocopy either! (Just in case anyone wonders how I know
> this, I type up test certs for an electrical contracting firm as part of
> my job.)
be creative - do most of it yourself but e.g. "forget" the main
equipot. bonding. or someat.
Then play dumb, get a sparks to quote - say you've recently bought it
and you'd like a full Perodic Inspection (with tests etc) doing
please.....
cheers
JimK
Owain
> If you check out part P then you'll find that there is very little that
> you *can* legally do now without being registered.
> You can't install any new circuits.
> You can't modify or change the CU.
> You *can* change a socket - even from single to double! :-)
> You can't change or install a light fitting in a shower.
> ...and lots of other stuff.
but you can, legally, if you put in a Building Regulations
application.
> Without the right (calibrated) gear there is no way that you can test an
> installation and issue a test certificate. Even the test certs are serial
> numbered and traceable back to the issuer so you can't scrounge a blank.
> They won't photocopy either! (Just in case anyone wonders how I know
> this, I type up test certs for an electrical contracting firm as part of
> my job.)
But the Installation and Test certificate format is (was) in the back
of the Regs and AFAIK nothing to stop someone typing up their own.
Owain
Tim W
wibbled on Monday 04 January 2010 09:47
>
>>A multimeter will not test insulation or continuity to the required
>>standard, but you can hire a 17th edition tester for a week/weekend
>>fairly cheaply (~£100)
>
> If you are using all new parts/cable and are competent at wiring, the
> probablility of a fault that would only be detectable by a 'proper' tester
> is negligible.
Yes, but don't read this as "no need to test at all".
First ring circuit I put in 2 weeks ago showed up a broken neutral on the
end-end test. This is with 35mm back boxes, all new parts, care when
assembling etc. I reckon it was the screw bit the cable too hard (my
personal faults is I tend to over tighten rather than under tighten things).
Just weakened it enough to cause the wire to snap when plate replaced.
So testing is important. But you could have found that with a multimeter.
Ditto a multimeter will find functional wiring errors on the figure-8 tests,
but it will not tell you if you have a bad connection or have damaged the
insulation. You'd probably get away without an IR test but I strongly rate
having a loop impedance meter.
It's also a good idea to prove the RCDs are in spec, though one could hash
this up with a carefully chosen resistor if you're prepared to not test the
trip time aspect.
But if you are doing a new installation, I think it is well worth the money
to aquire a second hand multifunction tester or single function meters) or
borrow/rent one for a day.
> For a makeshift insulation test, a low-range AC current meter across an
> open breaker should show up anything serious..
> Continuity test at high currents could also be improvised with a little
> imagination.
No argument there.
--
Tim Watts
This space intentionally left blank...
Tim W
wibbled on Monday 04 January 2010 09:43
>If you check out part P then you'll find that there is very little that
>you *can* legally do now without being registered.
Not correct. You can do it all under Building Control.
> You can't install any new circuits.
> You can't modify or change the CU.
> You *can* change a socket - even from single to double! :-)
> You can't change or install a light fitting in a shower.
> ...and lots of other stuff.
>
>> There seems to be quite an emphasis on testing circuits after
>> installation, but I'm unsure whether this is necessary where I know my
>> workmanship is good and the circuits are simple, and there is simple
>> continuity testing I can do with a multimeter. Anyway I'm keen to do
>> things properly so I'd be interested to hear what people's views are on
>> this and assuming I really do need to do proper testing (I think I do)
>> how can I do this without forking out hundreds for testing kit?
>>
>
> You're right. There is a lot of emphasis on testing. In order to get a
> test certificate this has to be carried out - and you are very unlikely
> to find any 'leccy who will test and issue an Electrical Installation
> Certificate (the one that you need) where someone else has done the work.
> Nowadays you should really have that certificate if you come to sell the
> house. :-(
The electrician will be more than happy to do a PIR though (and charge for
it) and a PIR is the usual mechanism by which Building Control validate your
work.
> Without the right (calibrated) gear there is no way that you can test an
> installation and issue a test certificate. Even the test certs are serial
> numbered and traceable back to the issuer so you can't scrounge a blank.
> They won't photocopy either! (Just in case anyone wonders how I know
> this, I type up test certs for an electrical contracting firm as part of
> my job.)
>
Not fully correct. You use IEE/IET modal forms freely downloadable from from
www.theiet.org. The serial numbered ones you are thinking of are the ones on
NICEIC (et al) pads.
But yes, you "properly" complete an EIC (that Building Control will believe)
you need calibrated test instruments.
Cheers
Tim
Andrew Gabriel
Tim W <t...@dionic.net> writes:
> Mike Harrison <mi...@whitewing.co.uk>
> wibbled on Monday 04 January 2010 09:47
>
>>
>>>A multimeter will not test insulation or continuity to the required
>>>standard, but you can hire a 17th edition tester for a week/weekend
>>>fairly cheaply (~£100)
>>
>> If you are using all new parts/cable and are competent at wiring, the
>> probablility of a fault that would only be detectable by a 'proper' tester
>> is negligible.
>
> Yes, but don't read this as "no need to test at all".
>
> First ring circuit I put in 2 weeks ago showed up a broken neutral on the
> end-end test. This is with 35mm back boxes, all new parts, care when
> assembling etc. I reckon it was the screw bit the cable too hard (my
> personal faults is I tend to over tighten rather than under tighten things).
> Just weakened it enough to cause the wire to snap when plate replaced.
Also, this is the first time you've used a new roll of cable.
Although I've never had a faulty roll, I would not simply assume
there are never any conductor breaks.
Last few complete ring circuits I've installed, I managed to get
the cable and sockets installed without a single cut in the conductors.
That does reduce the chance of an open-circuit ring.
> So testing is important. But you could have found that with a multimeter.
> Ditto a multimeter will find functional wiring errors on the figure-8 tests,
> but it will not tell you if you have a bad connection or have damaged the
> insulation. You'd probably get away without an IR test but I strongly rate
> having a loop impedance meter.
Another simple check you can do - using something like a 2kW heater
or 3kW kettle, check the voltage drop at one or two places around the
ring as you switch it on and off, and make sure it's roughly what you
expect.
> It's also a good idea to prove the RCDs are in spec, though one could hash
> this up with a carefully chosen resistor if you're prepared to not test the
> trip time aspect.
I made my own 20+ years ago. IME, RCD trip is so instant (i.e. vastly
shorter than the allowed times) that you have no difficulty seeing
this without time measuring equipment. (One day, I must add the DC
test to it though;-)
> But if you are doing a new installation, I think it is well worth the money
> to aquire a second hand multifunction tester or single function meters) or
> borrow/rent one for a day.
>
>> For a makeshift insulation test, a low-range AC current meter across an
>> open breaker should show up anything serious..
Yikes. May well show up as a test meter blowing up in your face
if there's a fault, or you accidentally touch the probe on the
wrong place..
>> Continuity test at high currents could also be improvised with a little
>> imagination.
>
> No argument there.
>
--
Tim W
wibbled on Monday 04 January 2010 11:10
> Also, this is the first time you've used a new roll of cable.
> Although I've never had a faulty roll, I would not simply assume
> there are never any conductor breaks.
>
> Last few complete ring circuits I've installed, I managed to get
> the cable and sockets installed without a single cut in the conductors.
> That does reduce the chance of an open-circuit ring.
That's certainly bomb proof :)
Sadly, for me it would mean feeding 20-25m of cable effectively through
every conduit drop and up again as all mine come down from the ceiling.
I *do* wish they'd use captive terminals in accessory plates though. In this
day and age, one *really* should not have to be worrying about whether the
3rd CPC went up the side of the screw and is about to fall out...
Andy Dingley
> If you check out part P then you'll find that there is very little that
> you *can* legally do now without being registered.
> You can't install any new circuits.
Yes you can, you just can't sign them off.
There's still the BCO route, and if you're looking at a full re-wire,
that can make sense.
Nutkey
> Andy Dingley <ding...@codesmiths.com>
> wibbled on Monday 04 January 2010 12:36
> nice job with <1k of materials then even if you either buy a Megger (etc) or
> have to pay for a PIR (either could be a few hundred plus the 100-200 for
I created a new kitchen ring and changed the main, garage, and shed
CU. The BCO accepted my EIC (and was pretty happy to, his first
question was "can you test it for us"). I bought a megger and did it
all properly.
> the BNA) then you are still winning, assuming you don't need to cost your
> time.
I priced it for the purposes of the BNA, but underestimated the number
of hours quite substantially :) I learned lots though...
> If you can persuade the BCO to accept your EIC then you are winning long
> term as you still have the Megger for future jobs. Running costs are 60 odd
> quid once in a while to have it calibrated if you are really anal. I hven't
> bothered with mine this year - it ready-reckons OK on the resistor card, so
> I'll probably have it redone just before I do the final (re)tests for the
> finished EIC[1]
45 quid I think, and he came to my house.
The guy who gave me the most hassle was from Siemens. I booked a
disconnect and reconnect for the mains as I didn't have an isolating
switch. So I screwed an isolator to the wall ran some tails out of it,
and when he turned up wondering why he had to do a disconnect and
reconnect *at the same time* I explained I wanted the old tails
disconnected and the new ones connected.
He didn't like that at all. He did it, but he came back at the end of
the day when I had things more or less done. He wanted to make sure I
had N and L the right way round, which he tested with a socket
tester... It beeped, he was happy.
Tim W
wibbled on Monday 04 January 2010 16:17
> He didn't like that at all. He did it, but he came back at the end of
> the day when I had things more or less done. He wanted to make sure I
> had N and L the right way round, which he tested with a socket
> tester... It beeped, he was happy.
EDF did that to me too - only he waved a voltstick over the wires in the CU.
Looks like arse-covering to me...
The trick for me was (as I had the main fuse out all day) to make an
exceedingly neat job of the wires in the meter box (including the isolator I
wasn't supposed to put there- ha) and I ran the tails into the CU in Kopex
pliable plastic 32mm conduit (seemed the best way to protect them going up
the soffit and over the wall leafs) with nice chunky IP65 glands into the
meter box.
After that he stopped complaining and became very helpful...
js.b1
Notifiable works...
- New final circuit
- New SWA to shed or garage
- Extending final circuit in kitchen & bathroom
- Changing a CU re enclosure and protective devices (CPD)
- etc
NON-Notifiable...
- Maintenance operations even in special locations or connected with
them
- Extending any circuit not in a special location (extending power
circuits, light circuits)
- Replacing a RCD, RCBO (eg, no trip on test button)
- Replacing a shower
- Replacing a SWA cable to a shed
- Replacing any circuit cable (circuit defined as supplied by a CPD)
- Changing an enclosure (including a CU enclosure, but not all CPD)
- Extending a porch, shed, garage circuit is not a special location
- etc
So a "rewire" may not require much notification at all.
Probably the CU, but unless you are gutting the house you can do bit
by bit - 20A radials per room are a good thing here because you can do
a room at a time re mess / time / cost.
MK Grid is fiddly to work with - but useful where you have a space
problem such as 300mm from sink on one side, wall on another side, and
4 switches or whatever to fit in.
Hall lights on dedicated or downstairs light circuit is a good idea -
most people put them on the upstairs circuit so when a (usually)
incandescent bulb pops the stairs and upstairs are plunged into
darkness.
Dedicated smoke alarm circuit, with heat alarm for kitchen.
Whatever you do, plan everything now if it is not easy to add stuff
later (solid floors, can't access ceilings re sprawling outhouses and
extensions, floors & ceilings on different levels). Alternatively
leave a few bits of conduit in place to ease replacement. Use a large
CU and put spare 20A radial circuits to a 20A DP switch which you can
extend later should the need arise :-)
js.b1
> First ring circuit I put in 2 weeks ago showed up a broken neutral on the
> end-end test. This is with 35mm back boxes, all new parts, care when
> assembling etc. I reckon it was the screw bit the cable too hard (my
> personal faults is I tend to over tighten rather than under tighten things).
It is very common, and down to the wiring accessory.
- RCBO & MCB use a T-bar off a screw to clamp multiple cores
- Wiring accessories use a bare screw and hope the cores grip equally,
don't stack, don't dislodge
The most common damage is 1mm lighting being squashed to nothing, bit
of flexion putting it back and it breaks (1.5mm FTE doesn't help much
as the CPC is 1mm also). This is one area where T-bar terminals would
help.
I have an SFCU irritatingly located close to the ceiling & close to a
wall which makes access difficult. The SFCU goes on to supply a
Class-1 outside light and a temporary outside socket, so integrity of
the earth is rather important (it does have RCBO protection). This
morning at 2:21am, with the wall open to repair plaster around an
architrave, I decided to change the backbox to 47mm from 35mm and use
a 5-way Wago Lever connector to link the earths - and a 6491X earth to
the SFCU. That way I know the earth remains perfect rather than one
coming out, twisted-together breaking etc.
The most important tester is an RCD tester.
You can get decent ones for about £125 on Ebay occasionally (whoever
electrical factor relabelled megger RCDT320), or used for less/more
depending on spec.
An IR (Insulation Resistance) tester is good, but over-rated.
Many types of cable deteriorate at the ends - TRS (& lead covered TRS)
suffers insulation falling off by rotting, Polyethylene suffers severe
insulation cracking if overheated, butyl suffers UV degradation, post-
WWII PVC suffering green goo can cause tracking at exposed ends. In
all those cases an IR test will often say "fine" so someone walks
away, in the first two of those cases a fire is quite possible
particularly if rewireable fuses provide OC protection.
Continuity & Polarity are critical - especially polarity w.r.t.
lighting with ES lamp holders. RCD testers usually check polarity
(they will not do a test on a LN reversal for starters, not uncommon
if something wired in low light re BL/BR colour rendering).
A reminder is to check smoke alarm are all wired correctly because
otherwise the cost is a whole set of new ones (£200+).
Brett Jackson
> On 3 Jan, 22:57, Brett Jackson wrote:
>> First thing to go is the fuse box. I can't seem to find any clear
>> guidance as to how I should utilise the 2 RCD's that you get with a
>> '17th edition' CU. There also seems to be some conflicting info (or
>> more probably some misunderstanding on my part) on the uk.d-i-y wiki
>> regarding what circuits should be RCD protected. It reads like 17th ed.
>> introduces some more stringent directives as to the protection of
>> circuits by RCD where T&E and other unprotected cables are buried in
>> walls below a certain depth, yet there is a suggestion that lighting and
>> some other circuits should remain unprotected. So, how would I arrange
>> my CU wrt the 2 RCD's and un-RCD'd circuits?
>
> You don't have any un-RCD'd circuits. The CU is split into two halves,
> and each half has an RCD. The idea is the whole house doesn't go off
> when an RCD trips. It's still a bit of an kludge compared with having
> individual RCBOs (combined MCB + RCD) for each individual circuit.
>
> Try to split the lighting circuits over the 2 RCDs so you don't lose
> all lights at once.
If I were to use RCBO's for the lighting circuits, would I still be
required to have 2 RCD's? It would seem to me that in using RCBO's I
would have exceeded the original requirement, albeit in a slightly
different manner to the accepted norm. I'm thinking that I can buy a
17th ed CU, use RCBO's as explained then use the second RCD in the garage...
>
>> I'm going to do the
>> re-wire stage by stage as I re-decorate each room, so I'll probably end
>> up with a couple of lighting circuits and half a dozen radial circuits
>> (one per room) for the sockets, plus a ring for the kitchen, CH, oven,
>> hob, garage etc.
>
> A radial for each room and you will need either a large CU or have
> some rooms without sockets! And you have a choice of using 2.5mm cable
> and only having 20A on a circuit, or having to use 4mm cable to get
> 32A on a circuit.
I'm looking at at least a 15 way CU, or maybe even 20+. The radials
would be 2.5mm T&E protected by 16 amp MCB's as I have no appliances
outside the kitchen that come close to needing even 13 amps.
>
> Hob will usually require a dedicated cooker circuit. Single oven might
> be less than 13A, but better placed on a cooker circuit IMO.
Oven and hob will be on their own MCB's
ARWadsworth
"Brett Jackson" <sp...@no.email> wrote in message
news:R9adndkCILinzN_W...@brightview.co.uk...
> On 03/01/2010 23:31, Owain wrote:
>> On 3 Jan, 22:57, Brett Jackson wrote:
>>> First thing to go is the fuse box. I can't seem to find any clear
>>> guidance as to how I should utilise the 2 RCD's that you get with a
>>> '17th edition' CU. There also seems to be some conflicting info (or
>>> more probably some misunderstanding on my part) on the uk.d-i-y wiki
>>> regarding what circuits should be RCD protected. It reads like 17th ed.
>>> introduces some more stringent directives as to the protection of
>>> circuits by RCD where T&E and other unprotected cables are buried in
>>> walls below a certain depth, yet there is a suggestion that lighting and
>>> some other circuits should remain unprotected. So, how would I arrange
>>> my CU wrt the 2 RCD's and un-RCD'd circuits?
>>
>> You don't have any un-RCD'd circuits. The CU is split into two halves,
>> and each half has an RCD. The idea is the whole house doesn't go off
>> when an RCD trips. It's still a bit of an kludge compared with having
>> individual RCBOs (combined MCB + RCD) for each individual circuit.
>>
>> Try to split the lighting circuits over the 2 RCDs so you don't lose
>> all lights at once.
>
> If I were to use RCBO's for the lighting circuits, would I still be
> required to have 2 RCD's? It would seem to me that in using RCBO's I
> would have exceeded the original requirement, albeit in a slightly
> different manner to the accepted norm. I'm thinking that I can buy a 17th
> ed CU, use RCBO's as explained then use the second RCD in the garage...
The words "17th editon CU" actually means "the basic minimum compliance of
the 17th edition regs".
I am still not sure that a dual RCD CU meets that requirement where mains
smoke alarms are fitted.
I now offer customers a choice of consumer units and explain the options and
price differences.
Adam
Andrew Gabriel
"ARWadsworth" <adamwa...@blueyonder.co.uk> writes:
>
> I now offer customers a choice of consumer units and explain the options and
> price differences.
Does anyone ever go for all RCBOs, or a significant proportion of RCBOs?
Brett Jackson
I had a chat today to my local BCO who does the Part P stuff. Very
helpful chap and the process seems straighforward and sensible.
Basically I pay my money and he pops round to have a look at what I'm
doing and discuss my requirements and how I'm going to meet them.
Another visit in my case after I've installed the CU, then a final
safety inspection when it's all done in a few years time.
The only mention of a PIR or sign-off other than standard BCO stuff was
a recommendation that I get a spark in to do a PIR when it's all done.
Finally (I think), are there any recommendations on CU/MCB brands? I
like the MK sockets and switches etc due to the quality, so I'm inclined
toward an MK CU, however they're more expensive than the others...
Tim W
wibbled on Monday 04 January 2010 21:27
I like Hager CUs - a very decent choice of devices and lots of enclosure
options.
I've been using GET accessories - they seem reliable and look nice and are
inexpensive. They do some nice grid based, but domestic appearance (ie not
pug ugly) light switches (and dimmers of various types, which is why grid is
cool - one dimmer + one switch in the same single plate - no problem... etc)
ARWadsworth
"Andrew Gabriel" <and...@cucumber.demon.co.uk> wrote in message
news:hhtlqr$fml$1...@news.eternal-september.org...
> In article <pAs0n.21994$Ym4....@text.news.virginmedia.com>,
> "ARWadsworth" <adamwa...@blueyonder.co.uk> writes:
>>
>> I now offer customers a choice of consumer units and explain the options
>> and
>> price differences.
>
> Does anyone ever go for all RCBOs, or a significant proportion of RCBOs?
>
> --
> Andrew Gabriel
I do a lot of "landlords specials" for 2 bed terraced houses. They use the
17th edition CU.
On larger properties I use a mixture of RCBOs and RCDs.
Only one customer has chosen all RCBOs
And I am not happy with the setup.
Adam
Owain
> > If I were to use RCBO's for the lighting circuits, would I still be
> > required to have 2 RCD's?
Not if every circuit is protected either by a RCD or a RCBO
> The words "17th editon CU" actually means "the basic minimum compliance of
> the 17th edition regs".
> I am still not sure that a dual RCD CU meets that requirement where mains
> smoke alarms are fitted.
I'm not convinced they actually comply with the 16th Edition regarding
unnecessary disconnection of circuits.
> I now offer customers a choice of consumer units and explain the options and
> price differences.
For a small installation MCBOs not excessively expensive, for 20+
circuits cost would be more.
No extra work to wire up though, and easy to rearrange the order of
circuits as new ones are added without having to juggle the neutral
and earth bars separately (for those people who like wires on the
busbars to be in the same order as the breakers).
DP isolation of individual circuits also useful when working on an
installation in stages.
Owain
Owain
> I'm looking at at least a 15 way CU, or maybe even 20+. The radials
> would be 2.5mm T&E protected by 16 amp MCB's as I have no appliances
> outside the kitchen that come close to needing even 13 amps.
Standard circuit is 20A.
You could always put uncompleted rings on 20A while the work is being
done (treat them as radials) and then change the MCB to 32A when the
ring is complete. Reuse the 20A for the immersion heater or similar;
even if you end up with a couple of redundant 20A MCBs it would still
be cheaper than a 20+ way CU.
Owain
Andrew Gabriel
Owain <spuorg...@gowanhill.com> writes:
> DP isolation of individual circuits also useful when working on an
> installation in stages.
Although I've used lots of RCBOs in many CU's, I've never used DP RCBOs.
Tim W
wibbled on Monday 04 January 2010 22:19
> DP isolation of individual circuits also useful when working on an
> installation in stages.
>
> Owain
The Hager single module RCBOs don't break the neutral - even though you have
to present the load's neutral to it for RCD purposes. The DP RCBOs are 2
module width - so best to be careful...
Andrew Gabriel
Brett Jackson <sp...@no.email> writes:
>
> Finally (I think), are there any recommendations on CU/MCB brands? I
> like the MK sockets and switches etc due to the quality, so I'm inclined
> toward an MK CU, however they're more expensive than the others...
I like MK sockets and switches, and MK MCBs/RCBOs, but not their
current plastic CU's. I liked the previous generation with clear
perspex covers. Last few I've done have all been commercial CU's
(MEM Memshield2, or whatever Eaton call them now), but they are
a good deal more expensive than residential grade CU's.
Steve Walker
> Read SI 2006 on ODPM. There are notifiable & non-notifiable works.
>
> Notifiable works...
> - New final circuit
> - New SWA to shed or garage
> - Extending final circuit in kitchen & bathroom
> - Changing a CU re enclosure and protective devices (CPD)
> - etc
>
> NON-Notifiable...
> - Maintenance operations even in special locations or connected with
> them
> - Extending any circuit not in a special location (extending power
> circuits, light circuits)
> - Replacing a RCD, RCBO (eg, no trip on test button)
> - Replacing a shower
> - Replacing a SWA cable to a shed
> - Replacing any circuit cable (circuit defined as supplied by a CPD)
> - Changing an enclosure (including a CU enclosure, but not all CPD)
> - Extending a porch, shed, garage circuit is not a special location
> - etc
Just out of interest. I have a garage with a shed right next to it (so
close that they share the same guttering - that took some careful
arrangement!). The garage is supplied with SWA to a consumer unit inside.
Is it notifiable to extend the circuits across the gap (due to the short
length, two T&Es in a plastic conduit just under the guttering should be
sufficient)?
SteveW
Steve Walker
I've been perfectly happy with my Crabtree Starbreaker CU, but then again
my father used to work for an electrical accessory manufacturer and sat on
(and chaired) a number of BS committees - when my house needed re-wiring 16
years ago, he asked his contacts at other companies for free samples (he
did tell them what for) and my entire house re-wire, including the CU, cost
me thirty quid! Some of it was slightly overdone though, such as the 16mm^2
T&E for the cooker point - hey it was free, but it was an absolute bastard
to get in the box! Typically, we now have a gas cooker!
SteveW
Brett Jackson
> On 4 Jan, 20:54, "ARWadsworth" wrote:
>>> If I were to use RCBO's for the lighting circuits, would I still be
>>> required to have 2 RCD's?
>
> Not if every circuit is protected either by a RCD or a RCBO
This is the conclusion I'm coming to as well. In fact the NICEIC state
in their FAQ that dual RCD is one of several solutions. I'm seeing it
as the lowest cost option to meet the req's, rather than a minimum standard.
There doesn't seem to be an electrical safety aspect to there being more
than one RCD as providing a circuit is RCD protected then it's
protected. The regulation seems to state reduction of inconvenience,
which read literally probably means lighting & fire, but with the caveat
that you don't want both lighting circuits on one RCD.
So, what I'm pondering is...
- a single RCD to cover all the sockets outside the kitchen, and maybe
CH, immersion heater etc.
- an unprotected circuit going out to the garage via SWA where
there'll be a sepearte CU with RCD.
- RCBO's for everything else - lighting, fire alarms, kitchen ring &
appliances
>
>> The words "17th editon CU" actually means "the basic minimum compliance of
>> the 17th edition regs".
>> I am still not sure that a dual RCD CU meets that requirement where mains
>> smoke alarms are fitted.
>
> I'm not convinced they actually comply with the 16th Edition regarding
> unnecessary disconnection of circuits.
>
>> I now offer customers a choice of consumer units and explain the options and
>> price differences.
>
> For a small installation MCBOs not excessively expensive, for 20+
> circuits cost would be more.
I was thinking 20 just to give plenty of empty slots for future
expansion. I'll probably only use half to begin with.
js.b1
> Just out of interest. I have a garage with a shed right
> next to it (so close that they share the same guttering
That sounds like a few inches...
> The garage is supplied with SWA to a consumer unit inside.
> Is it notifiable to extend the circuits across the gap (due to the
> short length, two T&Es in a plastic conduit just under the
> guttering should be sufficient)?
Heh-heh.
- You are allowed to fit an external light with cable entering at the
rear.
- You are allowed to maintain an existing external light where the
cable enters say from the bottom running along a wall.
- You are not allowed to fit an external socket because it can be used
to supply across a garden, however kits exist to do exactly that from
just about every DIY store in the country re B&Q, Wickes and I think
Homebase. Indeed I think some now exist with pre-fitted SWA in various
lengths to reach a distance socket which can be fitted into a shed or
on a wall.
Legally you could construct a wooden frame (tube) which spanned the
two entities and run cables through that - ensuring that the cable is
>50mm from any finished surface or run SWA w/glands inside it.
Practically do the job correctly to BS7671.
- I would not use conduit just under the guttering as an aluminium
ladder could be placed against it and crush it
- I would prefer to run SWA from the garage to the shed, more suitable
for outside use & earthed armour
- Alternatively ensure the conduit is visible and substantially
supported between two nearly touching buildings
Note if you are exporting PME from house to garage or shed...
- To do so requires 1) no incoming services (gas/water) 2) no
metalwork introducing a potential into the garage 3) floor is dry (not
likely with some garages) 4) no class-1 tools used outside or within a
damp garage - or you would need to TT supply the garage
- The same 4 criteria apply to exporting PME from garage to shed
- The only way to export PME where any of the 4 are broken is to use
an SWA back to the house of a sufficient conductor or armour cross-
sectional area to meet the MEB requirements and bond it back to the
MET accordingly (so the external garage/shed are at the same potential
as the house).
Note PME can not be exported to a caravan, some DNO are liberal in
their interpretation (such as steel containers to statics).
ARWadsworth
"Brett Jackson" <sp...@no.email> wrote in message
> On 04/01/2010 22:19, Owain wrote:
>> On 4 Jan, 20:54, "ARWadsworth" wrote:
>>>> If I were to use RCBO's for the lighting circuits, would I still be
>>>> required to have 2 RCD's?
>>
>> Not if every circuit is protected either by a RCD or a RCBO
>
> This is the conclusion I'm coming to as well. In fact the NICEIC state in
> their FAQ that dual RCD is one of several solutions. I'm seeing it as the
> lowest cost option to meet the req's, rather than a minimum standard.
>
> There doesn't seem to be an electrical safety aspect to there being more
> than one RCD as providing a circuit is RCD protected then it's protected.
> The regulation seems to state reduction of inconvenience, which read
> literally probably means lighting & fire, but with the caveat that you
> don't want both lighting circuits on one RCD.
>
> So, what I'm pondering is...
>
> - a single RCD to cover all the sockets outside the kitchen, and maybe
> CH, immersion heater etc.
> - an unprotected circuit going out to the garage via SWA where there'll
> be a sepearte CU with RCD.
> - RCBO's for everything else - lighting, fire alarms, kitchen ring &
> appliances
>>
I would consider putting the CH on it's own RCBO.
The last thing you want is a fault on another circuit taking out your
heating.
I quite often use a dual RCD CU that has some non RCD slots
eg http://www.tlc-direct.co.uk/Products/WYNHRS10SSLHI.html
I would then mix the lighting and sockets up between the two RCD and use
RCCBOs on the non RCD slots for smokes and mayby a kitchen ring or the CH
Adam
Tim..
> In article
> <e51018d3-6cdb-4012...@j5g2000yqm.googlegroups.com>,
> Owain <spuorg...@gowanhill.com> writes:
>> DP isolation of individual circuits also useful when working on an
>> installation in stages.
>
> Although I've used lots of RCBOs in many CU's, I've never used DP RCBOs.
I've often used some DP RCBO's for plant switchgear, and temporary installs.
Only prob is you end up with a CU that is 1 metric yard wide !!
Tim.
Steve Walker
> On Jan 4, 10:59�pm, Steve Walker <st...@theend.demon.co.uk> wrote:
>> Just out of interest. I have a garage with a shed right
>> next to it (so close that they share the same guttering
>
> That sounds like a few inches...
The gap is around eight inches, shed wall to garage wall.
>> The garage is supplied with SWA to a consumer unit inside.
>> Is it notifiable to extend the circuits across the gap (due to the
>> short length, two T&Es in a plastic conduit just under the
>> guttering should be sufficient)?
<snip>
> Practically do the job correctly to BS7671.
> - I would not use conduit just under the guttering as an aluminium
> ladder could be placed against it and crush it
Just about impossible - the conduit would be six inches to a foot in from
the end of the shed, an inch or less below the gutter crossing a gap of 8
inches. The gutter itself is overlapped by the roofs of both the garage and
shed, from opposite sides, with a gap of only two inches between them. The
chances of anything contacting it are vanishingly small.
> - I would prefer to run SWA from the garage to the shed, more suitable
> for outside use & earthed armour
The armour is probably not necessary, due to the above, unless for
earthing.
> - Alternatively ensure the conduit is visible and substantially
> supported between two nearly touching buildings
I would use steel conduit, but then we get into ensuring that that is
reliably earthed. White plastic conduit will certainly be visible against
the brown guttering.
> Note if you are exporting PME from house to garage or shed...
> - To do so requires 1) no incoming services (gas/water)
Not a problem.
> 2) no
> metalwork introducing a potential into the garage
Again no problem.
> 3) floor is dry (not
> likely with some garages)
Was a problem until recently, but re-covering the roof, properly sealing
the sectional concrete panels to the base slab and re-aligning the gutter
have solved that.
> 4) no class-1 tools used outside or within a
> damp garage - or you would need to TT supply the garage
Pretty sure that the only portable earthed tool I've got at the moment is
an old welder and that's not even mine and is only used inside anyway.
> - The same 4 criteria apply to exporting PME from garage to shed
> - The only way to export PME where any of the 4 are broken is to use
> an SWA back to the house of a sufficient conductor or armour cross-
> sectional area to meet the MEB requirements and bond it back to the
> MET accordingly (so the external garage/shed are at the same potential
> as the house).
Garage is already supplied via SWA and does indeed export the earth. All
done correctly already, RCDd, etc..
As TT is not really necessary for the shed as none of the four rules are
broken, I'll stick with exporting the earth and I'll probably just export
from the garage, as I really don't fancy digging a deep enough trench up
the garden from the house.
And as I started my post with "Just out of interest," I'll probably save
myself any hassles, use old colours and insist that it's been there for
years! Just in case anyone asks.
SteveW
Dave Osborne
>
> Garage is already supplied via SWA and does indeed export the earth. All
> done correctly already, RCDd, etc..
>
> As TT is not really necessary for the shed as none of the four rules are
> broken, I'll stick with exporting the earth and I'll probably just export
> from the garage, as I really don't fancy digging a deep enough trench up
> the garden from the house.
>
This is what I would do and not worry about it. ;-)
Owain
> > DP isolation of individual circuits also useful when working on an
> > installation in stages.
> to present the load's neutral to it for RCD purposes. The DP RCBOs are 2
> module width - so best to be careful...
Oh.
Suppose one uses the SP RCBOs and gets the tails the wrong way
round ... could be nasty.
Owain
ARWadsworth
"Owain" <spuorg...@gowanhill.com> wrote in message
news:56e470d1-8faa-4505...@k17g2000yqh.googlegroups.com...
But a tripped single pole RCBO still cuts the live or am I missing
something?
Adam
>
Owain
> > Suppose one uses the SP RCBOs and gets the tails the wrong way
> > round ... could be nasty.
> something?
"tails the wrong way round"
Owain