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Split load CU
Getting differing messages on what to protect (RCD) and what not...
What's the general view ? Lighting ... NO Ring Mains... YES Install a (unprotected) separate socket for Fridge Freezer Yes or No ? Cooker Outlet ..Yes or No ? Gas Boiler ... Yes or No ? Outside supply (unprotected) use individual plug-in RCD's for portable tools. Yes or No One guy I spoke to said: Install a CU with a 100mA main RCD and then use 30mA RCBO's but all the CU's I've seen have 30mA main RCD's ... Is this a real option ? and finally: If you were doing a re-wire now would you connect the bathroom lighting cct seperatly via a RCBO or is there danger that this requirement in the 17th edition will not be ratified. |
Split load CU
In article m,
ac1951 writes: Getting differing messages on what to protect (RCD) and what not... What's the general view ? Lighting ... NO Ring Mains... YES Install a (unprotected) separate socket for Fridge Freezer Yes or No ? Unprotected. Can also feed boiler, alarm, any life support systems (e.g. tropical fish tank with a dedicated plug-in RCD). Cooker Outlet ..Yes or No ? Unprotected. Gas Boiler ... Yes or No ? Unprotected. Outside supply (unprotected) use individual plug-in RCD's for portable tools. Yes or No Use an RCBO or separate hard-wired RCD from the unprotected side. (Individual plug-in RCD's wouldn't conform to regs.) I would also recommend an isolating switch for the outdoor circuit inside the house (which could be part of the RCD protection). One guy I spoke to said: Install a CU with a 100mA main RCD and then use 30mA RCBO's but all the CU's I've seen have 30mA main RCD's ... Is this a real option ? That option is only required if your earthing is via your own earth rod (TT system), rather than by an earthing terminal provided by the supply company (TN system). and finally: If you were doing a re-wire now would you connect the bathroom lighting cct seperatly via a RCBO or is there danger that this requirement in the 17th edition will not be ratified. There's no chance that what you describe will become the norm; RCBO's are too expensive and not available for many of the budget CU's often used in initial installs. I suspect it's most likely to be done with an FCU taking power from an RCD-protected ring circuit, which in effect replaces the fan isolator which becomes no longer necessary, so there's no cost increase. Personally, I would not RCD protect the bathroom light at this time, but I do fit them out of reach. I might consider RCD protection if the lighting was in reach, such as makeup lights around a mirror. -- Andrew Gabriel [email address is not usable -- followup in the newsgroup] |
Split load CU
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Split load CU
Andrew Gabriel wrote:
In article m, ac1951 writes: Getting differing messages on what to protect (RCD) and what not... What's the general view ? Lighting ... NO Ring Mains... YES Install a (unprotected) separate socket for Fridge Freezer Yes or No ? Unprotected. Can also feed boiler, alarm, any life support systems (e.g. tropical fish tank with a dedicated plug-in RCD). Cooker Outlet ..Yes or No ? Unprotected. Gas Boiler ... Yes or No ? Unprotected. I did a rewire recently, following the above scheme, and it was all checked over and approved by a sparks... however he mentioned that although he considered it barmy, he couldn't have approved it once the forthcoming 17th edn came in to force - I think the issue would have been over provision of the dedicated unprotected fridge/freezer socket? Is that so? - presumably would be resolvable by hardwiring the freezer with an FCU? David |
Split load CU
There's no chance that what you describe will become the norm; RCBO's
are too expensive and not available for many of the budget CU's often used in initial installs. I'm not so sure. Part of the reason for RCBO's expense will be the level of use. Once demand increases, price will drop. I suspect it's most likely to be done with an FCU taking power from an RCD-protected ring circuit, which in effect replaces the fan isolator which becomes no longer necessary, so there's no cost increase. Yup, agreed. Certainly to start with. |
Split load CU
I suspect it's most likely to be done with an FCU taking power from an
RCD-protected ring circuit, which ineffect replaces the fan isolator which becomes no longer necessary, so there's no cost increase. Yup, agreed. Certainly to start with. Would you install the FCU inside or outside the Bathroom ? |
Split load CU
In article . com,
ac1951 writes: I suspect it's most likely to be done with an FCU taking power from an RCD-protected ring circuit, which ineffect replaces the fan isolator which becomes no longer necessary, so there's no cost increase. Yup, agreed. Certainly to start with. Would you install the FCU inside or outside the Bathroom ? Inside, in Zone 3 or further (and out of reach for normal use). If it's not inside the bathroom, it would need to be able to be locked in the off position, which not all FCU's are (check for a padlock hole in the opened fuse carrier). -- Andrew Gabriel [email address is not usable -- followup in the newsgroup] |
Split load CU
"Andrew Gabriel" wrote in message ... In article m, ac1951 writes: Getting differing messages on what to protect (RCD) and what not... and finally: If you were doing a re-wire now would you connect the bathroom lighting cct seperatly via a RCBO or is there danger that this requirement in the 17th edition will not be ratified. There's no chance that what you describe will become the norm; RCBO's are too expensive and not available for many of the budget CU's often used in initial installs. I suspect it's most likely to be done with an FCU taking power from an RCD-protected ring circuit, which in effect replaces the fan isolator which becomes no longer necessary, so there's no cost increase. Personally, I would not RCD protect the bathroom light at this time, but I do fit them out of reach. I might consider RCD protection if the lighting was in reach, such as makeup lights around a mirror. It is my intention when the new rules come in to use an RCD fused spur off the lighting ciruit for the bathroom lights. This is for a cost reasons. Most houses do not have the CU near the bathroom and the labour for installing one radial off an RCBO for one room would have to be passed on to the customer. Adam |
More 17th edition (was Split load CU)
ac1951 wrote:
and finally: If you were doing a re-wire now would you connect the bathroom lighting cct seperatly via a RCBO or is there danger that this requirement in the 17th edition will not be ratified. I'd say there is no doubt at all that the 17th ed. will require 30 mA RCD protection for all bath/shower room circuits. Apparently the published 17th ed. (BS 7671:2008, due in January, effective from 1st July) will contain many changes from this year's draft edition, and these point in the direction of increased RCD protection (some may choose to call it paranoia). The REALLY BIG potential change (final decision said to be mid-November) concerns cables buried in walls at less than 50 mm depth. Here the requirement of the draft edition [522.6.6] is very similar to the 16th ed. in that such cables must comply with one of three options - i.e.: - use of a cable type with an earthed metal covering (SWA, FP200, Earthshield (BS 8436), etc.) or; - must be in earthed metal conduit or trunking (metal capping doesn't count), or; - must be in the "safe zones". For ordinary house wiring in T&E the safe zones option is of course the one used. Now the draft 17th added proposed reg. 522.6.7 which allowed a get-out, i.e. if none of the three above options could be applied then 30 mA RCD protection could be used instead, which seemed quite sensible. It now appears that all this will change, such that all power cables buried at less than 50 mm depth will require 30 mA RCD protection, _even_if_in_the_safe_zones_ unless one of the above special cable types, or metal conduit/trunking is used. Should this turn out to be true then _all_circuits_ wired in T&E will need to be 30 mA RCD'd, unless buried to what is normally an impracticable depth. Non-RCD protected circuits will need special cable types. Perhaps individual circuit RCBOs will become the norm... -- Andy |
cooker switch with integral socket (was Split load CU)
Andrew Gabriel wrote:
Just to add -- don't use a cooker switch with integral socket. Why not? Ta Andy |
cooker switch with integral socket (was Split load CU)
In article ,
Andy Champ writes: Andrew Gabriel wrote: Just to add -- don't use a cooker switch with integral socket. Why not? Don't really want the cooker RCD protected, but you do want all worktop sockets RCD protected, where things like kettles are plugged in. -- Andrew Gabriel [email address is not usable -- followup in the newsgroup] |
More 17th edition (was Split load CU)
In article ,
Andy Wade writes: It now appears that all this will change, such that all power cables buried at less than 50 mm depth will require 30 mA RCD protection, _even_if_in_the_safe_zones_ unless one of the above special cable types, or metal conduit/trunking is used. What's the justification for this? Or is it just knee jerk without any risk analysis to back it up? -- Andrew Gabriel [email address is not usable -- followup in the newsgroup] |
More 17th edition (was Split load CU)
Andrew Gabriel wrote:
What's the justification for this? I guess it's that it will give supplementary direct contact protection for people, ignorant of the safe zones concept, drilling, nailing or screwing through live cables. Or is it just knee jerk without any risk analysis to back it up? No idea. The makers of RCDs and the more expensive cable types will doubtless be pleased though... -- Andy |
Split load CU
ac1951 wrote:
Getting differing messages on what to protect (RCD) and what not... What's the general view ? Assuming you don't have a TT supply: Lighting ... NO No RCD Ring Mains... YES RCD Install a (unprotected) separate socket for Fridge Freezer Yes or No ? No RCD Cooker Outlet ..Yes or No ? No RCD Gas Boiler ... Yes or No ? No RCD Outside supply (unprotected) use individual plug-in RCD's for portable tools. Yes or No If you are just talking about sockets for feeding appliances outside then RCD. If you are talking abut submain feeds to outbuildiongs then see: http://wiki.diyfaq.org.uk/index.php?...ricity_outside One guy I spoke to said: Install a CU with a 100mA main RCD and then use 30mA RCBO's but all the CU's I've seen have 30mA main RCD's ... Is this a real option ? Hmm, I suspect he did not quite know what he was on about. This sort of setup is only really required on TT systems, and then the main RCD would need to be a time delayed type so as to discriminate with the downstream RCBOs on current imbalance faults. You can change the RCD in a CU if required for a different trip threshold one. and finally: If you were doing a re-wire now would you connect the bathroom lighting cct seperatly via a RCBO or is there danger that this requirement in the 17th edition will not be ratified. Can't see it changing in a big way now since the time for comments have passed and it will be issued soon. -- Cheers, John. /================================================== ===============\ | Internode Ltd - http://www.internode.co.uk | |-----------------------------------------------------------------| | John Rumm - john(at)internode(dot)co(dot)uk | \================================================= ================/ |
Split load CU
Lobster wrote:
I did a rewire recently, following the above scheme, and it was all checked over and approved by a sparks... however he mentioned that although he considered it barmy, he couldn't have approved it once the forthcoming 17th edn came in to force - I think the issue would have been over provision of the dedicated unprotected fridge/freezer socket? Is that so? - presumably would be resolvable by hardwiring the freezer with an FCU? As long as it was clearly labelled that the socket was for Freezer use only then IIUC it ought to be fine. -- Cheers, John. /================================================== ===============\ | Internode Ltd - http://www.internode.co.uk | |-----------------------------------------------------------------| | John Rumm - john(at)internode(dot)co(dot)uk | \================================================= ================/ |
Split load CU
Andrew Gabriel wrote:
Would you install the FCU inside or outside the Bathroom ? Inside, in Zone 3 or further (and out of reach for normal use). If it's not inside the bathroom, it would need to be able to be locked in the off position, which not all FCU's are (check for a padlock hole in the opened fuse carrier). pedant_mode What used to be Zone 3, but is now outside the zones ;-) /pedant_mode -- Cheers, John. /================================================== ===============\ | Internode Ltd - http://www.internode.co.uk | |-----------------------------------------------------------------| | John Rumm - john(at)internode(dot)co(dot)uk | \================================================= ================/ |
Split load CU
ARWadsworth wrote:
It is my intention when the new rules come in to use an RCD fused spur off the lighting ciruit for the bathroom lights. This is for a cost reasons. Most houses do not have the CU near the bathroom and the labour for installing one radial off an RCBO for one room would have to be passed on to the customer. There is also a certain logical elegance there in that turning off the lighting circuit for that floor will also turn off the bathroom lights. -- Cheers, John. /================================================== ===============\ | Internode Ltd - http://www.internode.co.uk | |-----------------------------------------------------------------| | John Rumm - john(at)internode(dot)co(dot)uk | \================================================= ================/ |
More 17th edition (was Split load CU)
Andy Wade wrote:
Should this turn out to be true then _all_circuits_ wired in T&E will need to be 30 mA RCD'd, unless buried to what is normally an impracticable depth. Non-RCD protected circuits will need special cable types. Perhaps individual circuit RCBOs will become the norm... Which by virtue of the switch drops would include lighting circuits as well. This would seem to have the same negative safety implications of the 15th edition "whole house RCD" all over again. -- Cheers, John. /================================================== ===============\ | Internode Ltd - http://www.internode.co.uk | |-----------------------------------------------------------------| | John Rumm - john(at)internode(dot)co(dot)uk | \================================================= ================/ |
More 17th edition (was Split load CU)
"Andrew Gabriel" wrote in message
... What's the justification for this? Or is it just knee jerk without any risk analysis to back it up? RCBO Lobbyists, er oops, Manufacturers :-) Quite seriously, the major manufacturers do directly drive IEE BS EU committee standards. They target the committee members quite relentlessly with a very blatant sales agenda. Challenge and you get a new corner office: window seat. It is endemic within the EU "health & safety" crowd. I am not surprised. I had expected "RCBO for every single final circuit" re IEE & Part P wording H&S-extremous. IEE will cite a) drilling-in-bathroom fatality re cable angle, or b) electrified spice rack, or c) other trades ignorant of zones. Q - Does FP200 qualify as concentric, earthed metal covering? I ask because whilst FP200 has a bare CPC in direct contact with a metal shield, the shield is merely electromagnetic shielding foil. Foil has substantially less fault current capability vs MICCs. I am thinking of cable penetration by ubiquitous picture nail, small dia, contacting only an small area of foil & phase. A small partial circumference of wafer thin foil carries fault current. For RCD protection that is 30ma, for 30A Type-C MCB it is 300A. Adiabatic calculation for that bit of foil would be interesting. MICCS, SWA & FP400 are all be ok, but is FP200?? FP200 has a 6r bend radius, 57mm for 2.5mm 2-core-&-earth. Keeping within 6r bend radius is not easy re plaster depth or conduit box rear exit (I suspect most strip the sheath off). -- DB. |
More 17th edition (was Split load CU)
The makers of RCDs and the more expensive
cable types will doubtless be pleased though... Is it Belgium or Portugal that requires basically a semi-armoured domestic cable? There are no zones, either cables are at some silly-depth or are armoured. France insulates the CPC, altho I wonder if in doing so they reduce the insulation thickness on Phase/N. Each country seems to use historic "freak case" to drive standards, the IEE/UK/Part-P picking every worst case to drive each one of its standards in the end. Plus they can not even quote the facts correctly in doing so. A brilliant way of creating committee employment. The result is a camel - and people use cowboys vs electricians, even more so when electricians/corgi milk people by fake regs. An important step in a formal risk management process is a cost benefit analysis. Now considering Part P, Brown, Govt in general, I suspect we should not expect any better. -- DB. |
More 17th edition (was Split load CU)
Dorothy Bradbury wrote:
IEE will cite a) drilling-in-bathroom fatality re cable angle, or b) electrified spice rack, or c) other trades ignorant of zones. And IEC, CENELEC and the H-word... Q - Does FP200 qualify as concentric, earthed metal covering? FP200 Gold, as it's now called, is to BS 7629-1, which is not one of the standards listed in 522-06-06 (522.6.6 in draft 17th ed.) - so no. Apologies for misleading you in an earlier post. I ask because whilst FP200 has a bare CPC in direct contact with a metal shield, the shield is merely electromagnetic shielding foil. Foil has substantially less fault current capability vs MICCs. I am thinking of cable penetration by ubiquitous picture nail, small dia, contacting only an small area of foil & phase. A small partial circumference of wafer thin foil carries fault current. For RCD protection that is 30ma, for 30A Type-C MCB it is 300A. Adiabatic calculation for that bit of foil would be interesting. MICCS, SWA & FP400 are all be ok, but is FP200?? The same issue arises with the BS 8436 cables: you're confined to Type B MCBs or RCBOs of energy limiting class 3. This MS Word document from the ECA has chapter and verse: http://www.voltimum.co.uk//popup.php...rd,%252029.5kB -- Andy |
More 17th edition (was Split load CU)
The same issue arises with the BS 8436 cables: you're confined
to Type B MCBs or RCBOs of energy limiting class 3. This MS Word document from the ECA has chapter and verse: http://www.voltimum.co.uk//popup.php...rd,%252029.5kB Great - thanks for the clarification. Had no plans to knock nails into cables :-))) -- DB. |
Split load CU
On Sat, 10 Nov 2007 14:44:31 GMT someone who may be "ARWadsworth"
wrote this:- It is my intention when the new rules come in to use an RCD fused spur off the lighting ciruit for the bathroom lights. This is for a cost reasons. Most houses do not have the CU near the bathroom and the labour for installing one radial off an RCBO for one room would have to be passed on to the customer. Also in a "typical" two floor house with the bathroom upstairs the upstairs lighting circuit is likely to be easily accessible, unlike the upstairs power circuits which are likely to be under the upstairs floor. -- David Hansen, Edinburgh I will *always* explain revoked encryption keys, unless RIP prevents me http://www.opsi.gov.uk/acts/acts2000/00023--e.htm#54 |
Split load CU
"David Hansen" wrote in message ... On Sat, 10 Nov 2007 14:44:31 GMT someone who may be "ARWadsworth" wrote this:- It is my intention when the new rules come in to use an RCD fused spur off the lighting ciruit for the bathroom lights. This is for a cost reasons. Most houses do not have the CU near the bathroom and the labour for installing one radial off an RCBO for one room would have to be passed on to the customer. Also in a "typical" two floor house with the bathroom upstairs the upstairs lighting circuit is likely to be easily accessible, unlike the upstairs power circuits which are likely to be under the upstairs floor. I suspect the cost of the RCD fused spur will be offset by not having to supply earth clamps and the time saved laying the 4mm earth cable for the supplemetary bonding. The other reason is that if the RCD fused spur trips due to moisure ingress any call outs are not urgent as the customers TV is still working. Adam |
Split load CU
It is my intention when the new rules come in to use an RCD fused spur off the lighting ciruit for the bathroom lights. This is for a cost reasons. Most houses do not have the CU near the bathroom and the labour for installing one radial off an RCBO for one room would have to be passed on to the customer. In my case the CH combi boiler is in a cupboard (old airing cupboard) in the bathroom. Does that mean the supply to this would need to be RCD protected. |
More 17th edition (was Split load CU)
Andrew Gabriel wrote:
In article , Andy Wade writes: It now appears that all this will change, such that all power cables buried at less than 50 mm depth will require 30 mA RCD protection, _even_if_in_the_safe_zones_ unless one of the above special cable types, or metal conduit/trunking is used. What's the justification for this? Or is it just knee jerk without any risk analysis to back it up? What will it cost over the next 20 years? With a 40 year mean installation life, 30 million houses and 1 extra rcbo (dropped to a mean £15 price) thats 0.5x 30 mill x £15 = £225 million. And how many lives will it save: judging by the last 20 years about 2. £112 milion per life saved. Compare this to the numerous other ways to save lives in quantity at a fraction of the cost... hard to see how it can be a sensibly analysed policy, though I'm open to education. NT |
More 17th edition (was Split load CU)
|
Split load CU
"ARWadsworth" wrote in message .uk... "Andrew Gabriel" wrote in message ... In article m, ac1951 writes: Getting differing messages on what to protect (RCD) and what not... and finally: If you were doing a re-wire now would you connect the bathroom lighting cct seperatly via a RCBO or is there danger that this requirement in the 17th edition will not be ratified. There's no chance that what you describe will become the norm; RCBO's are too expensive and not available for many of the budget CU's often used in initial installs. I suspect it's most likely to be done with an FCU taking power from an RCD-protected ring circuit, which in effect replaces the fan isolator which becomes no longer necessary, so there's no cost increase. Personally, I would not RCD protect the bathroom light at this time, but I do fit them out of reach. I might consider RCD protection if the lighting was in reach, such as makeup lights around a mirror. It is my intention when the new rules come in to use an RCD fused spur off the lighting ciruit for the bathroom lights. This is for a cost reasons. Most houses do not have the CU near the bathroom and the labour for installing one radial off an RCBO for one room would have to be passed on to the customer. Fitting an RCD fused spur off the lighting circuit and supplying the b/room lights and fans, etc, would this preclude equipotential bonding in a bathroom? |
Split load CU
"John Rumm" wrote in message ... ARWadsworth wrote: It is my intention when the new rules come in to use an RCD fused spur off the lighting ciruit for the bathroom lights. This is for a cost reasons. Most houses do not have the CU near the bathroom and the labour for installing one radial off an RCBO for one room would have to be passed on to the customer. There is also a certain logical elegance there in that turning off the lighting circuit for that floor will also turn off the bathroom lights. It would if there was an RCD or not. |
Split load CU
"ac1951" wrote in message oups.com... It is my intention when the new rules come in to use an RCD fused spur off the lighting ciruit for the bathroom lights. This is for a cost reasons. Most houses do not have the CU near the bathroom and the labour for installing one radial off an RCBO for one room would have to be passed on to the customer. In my case the CH combi boiler is in a cupboard (old airing cupboard) in the bathroom. Does that mean the supply to this would need to be RCD protected. If it is in a cupboard, no, as far as I believe. |
Split load CU
"Doctor Drivel" wrote in message reenews.net... "ARWadsworth" wrote in message .uk... "Andrew Gabriel" wrote in message ... In article m, ac1951 writes: Getting differing messages on what to protect (RCD) and what not... and finally: If you were doing a re-wire now would you connect the bathroom lighting cct seperatly via a RCBO or is there danger that this requirement in the 17th edition will not be ratified. There's no chance that what you describe will become the norm; RCBO's are too expensive and not available for many of the budget CU's often used in initial installs. I suspect it's most likely to be done with an FCU taking power from an RCD-protected ring circuit, which in effect replaces the fan isolator which becomes no longer necessary, so there's no cost increase. Personally, I would not RCD protect the bathroom light at this time, but I do fit them out of reach. I might consider RCD protection if the lighting was in reach, such as makeup lights around a mirror. It is my intention when the new rules come in to use an RCD fused spur off the lighting ciruit for the bathroom lights. This is for a cost reasons. Most houses do not have the CU near the bathroom and the labour for installing one radial off an RCBO for one room would have to be passed on to the customer. Fitting an RCD fused spur off the lighting circuit and supplying the b/room lights and fans, etc, would this preclude equipotential bonding in a bathroom? AFAIK the 17th edition not require supplemetary bonding in bathrooms but all electrical circuits in the bathroom will need to be 30mA RCD protected. Adam |
Split load CU
"ARWadsworth" wrote in message .uk... "Doctor Drivel" wrote in message reenews.net... "ARWadsworth" wrote in message .uk... "Andrew Gabriel" wrote in message ... In article m, ac1951 writes: Getting differing messages on what to protect (RCD) and what not... and finally: If you were doing a re-wire now would you connect the bathroom lighting cct seperatly via a RCBO or is there danger that this requirement in the 17th edition will not be ratified. There's no chance that what you describe will become the norm; RCBO's are too expensive and not available for many of the budget CU's often used in initial installs. I suspect it's most likely to be done with an FCU taking power from an RCD-protected ring circuit, which in effect replaces the fan isolator which becomes no longer necessary, so there's no cost increase. Personally, I would not RCD protect the bathroom light at this time, but I do fit them out of reach. I might consider RCD protection if the lighting was in reach, such as makeup lights around a mirror. It is my intention when the new rules come in to use an RCD fused spur off the lighting ciruit for the bathroom lights. This is for a cost reasons. Most houses do not have the CU near the bathroom and the labour for installing one radial off an RCBO for one room would have to be passed on to the customer. Fitting an RCD fused spur off the lighting circuit and supplying the b/room lights and fans, etc, would this preclude equipotential bonding in a bathroom? AFAIK the 17th edition not require supplemetary bonding in bathrooms but all electrical circuits in the bathroom will need to be 30mA RCD protected. ...and the 17th has not been ratified yet!!! |
Split load CU
wrote in message s.com... There's no chance that what you describe will become the norm; RCBO's are too expensive and not available for many of the budget CU's often used in initial installs. I'm not so sure. Part of the reason for RCBO's expense will be the level of use. Once demand increases, price will drop. I have the impression they want RCBOs to be the norm as they are Germany in new builds or re-wires. |
Split load CU
Doctor Drivel wrote:
It is my intention when the new rules come in to use an RCD fused spur off the lighting ciruit for the bathroom lights. This is for a cost reasons. Most houses do not have the CU near the bathroom and the labour for installing one radial off an RCBO for one room would have to be passed on to the customer. There is also a certain logical elegance there in that turning off the lighting circuit for that floor will also turn off the bathroom lights. It would if there was an RCD or not. Not if the bathroom lighting is wired from a FCU fed by a socket circuit, which would be the cheapest way of meeting the requirement since the socket circuit will already have the pre-requisite RCD protection. -- Cheers, John. /================================================== ===============\ | Internode Ltd - http://www.internode.co.uk | |-----------------------------------------------------------------| | John Rumm - john(at)internode(dot)co(dot)uk | \================================================= ================/ |
Split load CU
"John Rumm" wrote in message ... Doctor Drivel wrote: It is my intention when the new rules come in to use an RCD fused spur off the lighting ciruit for the bathroom lights. This is for a cost reasons. Most houses do not have the CU near the bathroom and the labour for installing one radial off an RCBO for one room would have to be passed on to the customer. There is also a certain logical elegance there in that turning off the lighting circuit for that floor will also turn off the bathroom lights. It would if there was an RCD or not. Not if the bathroom lighting is wired from a FCU fed by a socket circuit, He didn't say that. He mentioned the lighting circuit. Having an FCU/RCD off the lighting circuit to supply all of the power in bathroom (light and fan), which is normal, will only need one RCD off the lighting circuit. which would be the cheapest way of meeting the requirement since the socket circuit will already have the pre-requisite RCD protection. What you are proposing is have all the bathroom power off an RCD socket circuit via a fused spur to conform to the 17th and do away with equipotential bonding. It will work, but you have a lighting circuit not on the lighting circuit, which confuses. |
Split load CU
"ARWadsworth" wrote in message .uk... "Doctor Drivel" wrote in message reenews.net... "ARWadsworth" wrote in message .uk... "Andrew Gabriel" wrote in message ... In article m, ac1951 writes: Getting differing messages on what to protect (RCD) and what not... and finally: If you were doing a re-wire now would you connect the bathroom lighting cct seperatly via a RCBO or is there danger that this requirement in the 17th edition will not be ratified. There's no chance that what you describe will become the norm; RCBO's are too expensive and not available for many of the budget CU's often used in initial installs. I suspect it's most likely to be done with an FCU taking power from an RCD-protected ring circuit, which in effect replaces the fan isolator which becomes no longer necessary, so there's no cost increase. Personally, I would not RCD protect the bathroom light at this time, but I do fit them out of reach. I might consider RCD protection if the lighting was in reach, such as makeup lights around a mirror. It is my intention when the new rules come in to use an RCD fused spur off the lighting ciruit for the bathroom lights. This is for a cost reasons. Most houses do not have the CU near the bathroom and the labour for installing one radial off an RCBO for one room would have to be passed on to the customer. Fitting an RCD fused spur off the lighting circuit and supplying the b/room lights and fans, etc, would this preclude equipotential bonding in a bathroom? AFAIK the 17th edition not require supplemetary bonding in bathrooms but all electrical circuits in the bathroom will need to be 30mA RCD protected. When is the 17th coming in? |
Split load CU
"ARWadsworth" wrote in message .uk... "Doctor Drivel" wrote in message reenews.net... "ARWadsworth" wrote in message .uk... "Andrew Gabriel" wrote in message ... In article m, ac1951 writes: Getting differing messages on what to protect (RCD) and what not... and finally: If you were doing a re-wire now would you connect the bathroom lighting cct seperatly via a RCBO or is there danger that this requirement in the 17th edition will not be ratified. There's no chance that what you describe will become the norm; RCBO's are too expensive and not available for many of the budget CU's often used in initial installs. I suspect it's most likely to be done with an FCU taking power from an RCD-protected ring circuit, which in effect replaces the fan isolator which becomes no longer necessary, so there's no cost increase. Personally, I would not RCD protect the bathroom light at this time, but I do fit them out of reach. I might consider RCD protection if the lighting was in reach, such as makeup lights around a mirror. It is my intention when the new rules come in to use an RCD fused spur off the lighting ciruit for the bathroom lights. This is for a cost reasons. Most houses do not have the CU near the bathroom and the labour for installing one radial off an RCBO for one room would have to be passed on to the customer. Fitting an RCD fused spur off the lighting circuit and supplying the b/room lights and fans, etc, would this preclude equipotential bonding in a bathroom? AFAIK the 17th edition not require supplemetary bonding in bathrooms but all electrical circuits in the bathroom will need to be 30mA RCD protected. If the lighting in a bathroom is all 12v, do you need equipotential bonding in the 16th? In the 17th having 12v lighting, does it need to be RCD protected? |
Split load CU
Doctor Drivel wrote:
It would if there was an RCD or not. Not if the bathroom lighting is wired from a FCU fed by a socket circuit, He didn't say that. He mentioned the lighting circuit. Having an FCU/RCD Indeed, and I agreed that it was an elegant solution. which would be the cheapest way of meeting the requirement since the socket circuit will already have the pre-requisite RCD protection. What you are proposing is have all the bathroom power off an RCD socket circuit via a fused spur to conform to the 17th and do away with equipotential bonding. It will work, but you have a lighting circuit not on the lighting circuit, which confuses. see above... do try and keep up. -- Cheers, John. /================================================== ===============\ | Internode Ltd - http://www.internode.co.uk | |-----------------------------------------------------------------| | John Rumm - john(at)internode(dot)co(dot)uk | \================================================= ================/ |
Split load CU
"ARWadsworth" wrote in message .uk... "Doctor Drivel" wrote in message reenews.net... "ARWadsworth" wrote in message .uk... "Andrew Gabriel" wrote in message ... In article m, ac1951 writes: Getting differing messages on what to protect (RCD) and what not... and finally: If you were doing a re-wire now would you connect the bathroom lighting cct seperatly via a RCBO or is there danger that this requirement in the 17th edition will not be ratified. There's no chance that what you describe will become the norm; RCBO's are too expensive and not available for many of the budget CU's often used in initial installs. I suspect it's most likely to be done with an FCU taking power from an RCD-protected ring circuit, which in effect replaces the fan isolator which becomes no longer necessary, so there's no cost increase. Personally, I would not RCD protect the bathroom light at this time, but I do fit them out of reach. I might consider RCD protection if the lighting was in reach, such as makeup lights around a mirror. It is my intention when the new rules come in to use an RCD fused spur off the lighting ciruit for the bathroom lights. This is for a cost reasons. Most houses do not have the CU near the bathroom and the labour for installing one radial off an RCBO for one room would have to be passed on to the customer. Fitting an RCD fused spur off the lighting circuit and supplying the b/room lights and fans, etc, would this preclude equipotential bonding in a bathroom? AFAIK the 17th edition not require supplemetary bonding in bathrooms but all electrical circuits in the bathroom will need to be 30mA RCD protected. I have read that the 17th will allow 3-pin mains voltage sockets in bathrooms, as long as it is RCD protected. Is that so? If so, then a socket off the ring main can be just run in. Probably have to be away from the sink with minimum distance, etc.. |
More 17th edition (was Split load CU)
"John Rumm" wrote in message ... Andy Wade wrote: Should this turn out to be true then _all_circuits_ wired in T&E will need to be 30 mA RCD'd, unless buried to what is normally an impracticable depth. Non-RCD protected circuits will need special cable types. Perhaps individual circuit RCBOs will become the norm... Which by virtue of the switch drops would include lighting circuits as well. This would seem to have the same negative safety implications of the 15th edition "whole house RCD" all over again. It is pretty clear they are forcing everyone to use RCBOs. Rather than a bank of circuits being switched out by an RCD, each individual circuit only need switching out by its own RCBO. |
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