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Thoughts on fitting RCBOs
Hi all, especially the knowledgeable electricians on here.
What are your thoughts on me replacing all of the MCBs in my CU with RCBOs? At present I have 14 MCBs all protected by one 30mA RCD main switch. Over the last few years I've had tripping problems from a trapped L to E fault in a metal clad light unit, it too 10 years before this became a problem! Water blowing into an extractor fan, water in an outside light and the big issue of too many switch mode PSUs in the house. While some of the genuine faults were a pain and time consuming to locate the SMPSUs are something I have to live with and they are taking my overall leakage too near the 30mA limit on the CU. This has been brought to a head by a few trips this evening, no one circuit being the culprit, leave any 2 or 3 MCBs off and it is happy, just not happy with all on, I'm assuming something is leaking a bit more than normal and has taken the main RCD to it's limit. I've left one circuit off that has a number of SMPSUs on it and so far all is stable again. Yes I will turn everything off and check the trip current of the1 RCD in case it has become overly sensitive, but NOT tonight! So my thought was to replace the main switch/RCD with a simple switch and then all of the MCBs with RCBOs, everything will be protected and in the event of a real problem I don't lose the whole darn house, just the one errant circuit. So is it a practical idea? I think so, but would welcome any thoughts, good or bad about doing it. I know the 17th edition suggests a split load CU, but that would still leave me with a 50/50% split and a gamble as to what worked and what didn't. Yes I am competent to do it, just nervous that I may have missed a fundamental flaw in the idea. If it matters the CU is a Crabtree Starbreaker with a single 80A switch/30mA RCD and 14 MCBs and a DIN mount bell transformer. Apart from the cost, am I crazy? -- Bill ( A different one ) |
Thoughts on fitting RCBOs
On 23/10/2013 22:50, Bill wrote:
Hi all, especially the knowledgeable electricians on here. What are your thoughts on me replacing all of the MCBs in my CU with RCBOs? At present I have 14 MCBs all protected by one 30mA RCD main switch. Over the last few years I've had tripping problems from a trapped L to E fault in a metal clad light unit, it too 10 years before this became a problem! Water blowing into an extractor fan, water in an outside light and the big issue of too many switch mode PSUs in the house. While some of the genuine faults were a pain and time consuming to locate the SMPSUs are something I have to live with and they are taking my overall leakage too near the 30mA limit on the CU. This has been brought to a head by a few trips this evening, no one circuit being the culprit, leave any 2 or 3 MCBs off and it is happy, just not happy with all on, I'm assuming something is leaking a bit more than normal and has taken the main RCD to it's limit. I've left one circuit off that has a number of SMPSUs on it and so far all is stable again. Yes I will turn everything off and check the trip current of the1 RCD in case it has become overly sensitive, but NOT tonight! So my thought was to replace the main switch/RCD with a simple switch and then all of the MCBs with RCBOs, everything will be protected and in the event of a real problem I don't lose the whole darn house, just the one errant circuit. So is it a practical idea? I think so, but would welcome any thoughts, good or bad about doing it. I know the 17th edition suggests a split load CU, but that would still leave me with a 50/50% split and a gamble as to what worked and what didn't. Yes I am competent to do it, just nervous that I may have missed a fundamental flaw in the idea. If it matters the CU is a Crabtree Starbreaker with a single 80A switch/30mA RCD and 14 MCBs and a DIN mount bell transformer. Apart from the cost, am I crazy? I have done exactly what you propose. I previously had a MK metal clad CU with split rails. there were 2 off 6A MCBs feeding two lighting circuits (up and down) and 4 MCBS fed from a 30mA RCD. the 4 MCBs were for cooker, immersion, left hand side ring main, right hand side ring main. I basically ended up replacing the entire CU with a Curve Unit. You can get them from Denmans. I have a double pole on-off switch and can have up to 19 RCBO's I took the opportunity to split some circuits and add new ones. I now have: outside & garage lighting ground floor lighting first floor lighting loft lighting smoke, heat, CO detectors and intruder alarm boiler & immersion garage & outside sockets front left sockets front right sockets Rear left sockets Rear right sockets loft sockets Kitchen sockets cooker and I have 5 spare ways for the future. since doing it, I have not had a single trip. Prior to all this, I had all the problems you describe. |
Thoughts on fitting RCBOs
On 23/10/2013 22:50, Bill wrote:
Hi all, especially the knowledgeable electricians on here. What are your thoughts on me replacing all of the MCBs in my CU with RCBOs? At present I have 14 MCBs all protected by one 30mA RCD main switch. Over the last few years I've had tripping problems from a trapped L to E fault in a metal clad light unit, it too 10 years before this became a problem! Water blowing into an extractor fan, water in an outside light and the big issue of too many switch mode PSUs in the house. While some of the genuine faults were a pain and time consuming to locate the SMPSUs are something I have to live with and they are taking my overall leakage too near the 30mA limit on the CU. snip Apart from the cost, am I crazy? 14 MCBs? Jesus H. :D |
Thoughts on fitting RCBOs
In message om, bm
writes On 23/10/2013 22:50, Bill wrote: Hi all, especially the knowledgeable electricians on here. What are your thoughts on me replacing all of the MCBs in my CU with RCBOs? At present I have 14 MCBs all protected by one 30mA RCD main switch. Over the last few years I've had tripping problems from a trapped L to E fault in a metal clad light unit, it too 10 years before this became a problem! Water blowing into an extractor fan, water in an outside light and the big issue of too many switch mode PSUs in the house. While some of the genuine faults were a pain and time consuming to locate the SMPSUs are something I have to live with and they are taking my overall leakage too near the 30mA limit on the CU. snip Apart from the cost, am I crazy? 14 MCBs? Jesus H. That isn't including the annexe, which is fed from a separate CU!! :D -- Bill |
Thoughts on fitting RCBOs
In message om, bm
writes 14 MCBs? Jesus H. :D http://s117.photobucket.com/user/G8I...ps287ce74d.jpg ..html -- Bill |
Thoughts on fitting RCBOs
On 23/10/2013 23:46, Bill wrote:
In message om, bm writes 14 MCBs? Jesus H. :D http://s117.photobucket.com/user/G8I...ps287ce74d.jpg .html LOL Ahhhh yes, I've blunted many a drill bit in the RS PCB drill :D God i'm getting old. |
Thoughts on fitting RCBOs
On 23/10/2013 22:50, Bill wrote:
Hi all, especially the knowledgeable electricians on here. What are your thoughts on me replacing all of the MCBs in my CU with RCBOs? At present I have 14 MCBs all protected by one 30mA RCD main switch. Over the last few years I've had tripping problems from a trapped L to E fault in a metal clad light unit, it too 10 years before this became a problem! Water blowing into an extractor fan, water in an outside light and the big issue of too many switch mode PSUs in the house. While some of the genuine faults were a pain and time consuming to locate the SMPSUs are something I have to live with and they are taking my overall leakage too near the 30mA limit on the CU. This has been brought to a head by a few trips this evening, no one circuit being the culprit, leave any 2 or 3 MCBs off and it is happy, just not happy with all on, I'm assuming something is leaking a bit more than normal and has taken the main RCD to it's limit. I've left one circuit off that has a number of SMPSUs on it and so far all is stable again. Your experience adequately illustrates why the "whole house" RCD arrangement is deprecated - it was never a great idea, and the march of time (and things with leaky input filters) has only made the limitations more apparent. Yes I will turn everything off and check the trip current of the1 RCD in case it has become overly sensitive, but NOT tonight! So my thought was to replace the main switch/RCD with a simple switch and then all of the MCBs with RCBOs, everything will be protected and in the event of a real problem I don't lose the whole darn house, just the one errant circuit. So is it a practical idea? Practical - yes certainly. Its the "Rolls Royce" solution that gives the best possible discrimination in the even of an earth fault. Obviously its more expensive than other options. I think so, but would welcome any thoughts, good or bad about doing it. I know the 17th edition suggests a split load CU, but that would still leave me with a 50/50% split and a gamble as to what worked and what didn't. Split load does not have to mean a 50/50 split. Some 17th edition CUs may have say 4 RCDs and some unprotected (aka "high integrity") ways as well (for feeding circuits that meet the requirements for not being RCD protected). You can also arrange the split in various combinations of ways as suits your application. Yes I am competent to do it, just nervous that I may have missed a fundamental flaw in the idea. If it matters the CU is a Crabtree Starbreaker with a single 80A switch/30mA RCD and 14 MCBs and a DIN mount bell transformer. Without checking I don't know if you can get single module wide RCBOs for this enclosure (and if so if there is really enough space to wire them). You may find you need to replace the enclosure as well. Apart from the cost, am I crazy? No, although you probably ought to look at some pragmatic options. You may find a combination of several RCDs covering a two or three circuits each, plus a smaller number of RCBOs would make for a system that is equally effective, but also leave more money to spend on improving other aspects of the system. -- Cheers, John. /================================================== ===============\ | Internode Ltd - http://www.internode.co.uk | |-----------------------------------------------------------------| | John Rumm - john(at)internode(dot)co(dot)uk | \================================================= ================/ |
Thoughts on fitting RCBOs
On 23/10/2013 23:30, Bill wrote:
In message om, bm writes On 23/10/2013 22:50, Bill wrote: Hi all, especially the knowledgeable electricians on here. What are your thoughts on me replacing all of the MCBs in my CU with RCBOs? At present I have 14 MCBs all protected by one 30mA RCD main switch. Over the last few years I've had tripping problems from a trapped L to E fault in a metal clad light unit, it too 10 years before this became a problem! Water blowing into an extractor fan, water in an outside light and the big issue of too many switch mode PSUs in the house. While some of the genuine faults were a pain and time consuming to locate the SMPSUs are something I have to live with and they are taking my overall leakage too near the 30mA limit on the CU. snip Apart from the cost, am I crazy? 14 MCBs? Jesus H. That isn't including the annexe, which is fed from a separate CU!! I was about to say, 14 sounds a bit restrictive ;-) -- Cheers, John. /================================================== ===============\ | Internode Ltd - http://www.internode.co.uk | |-----------------------------------------------------------------| | John Rumm - john(at)internode(dot)co(dot)uk | \================================================= ================/ |
Thoughts on fitting RCBOs
On Wednesday 23 October 2013 22:50 Bill wrote in uk.d-i-y:
Hi all, especially the knowledgeable electricians on here. What are your thoughts on me replacing all of the MCBs in my CU with RCBOs? At present I have 14 MCBs all protected by one 30mA RCD main switch. Over the last few years I've had tripping problems from a trapped L to E fault in a metal clad light unit, it too 10 years before this became a problem! Water blowing into an extractor fan, water in an outside light and the big issue of too many switch mode PSUs in the house. While some of the genuine faults were a pain and time consuming to locate the SMPSUs are something I have to live with and they are taking my overall leakage too near the 30mA limit on the CU. This has been brought to a head by a few trips this evening, no one circuit being the culprit, leave any 2 or 3 MCBs off and it is happy, just not happy with all on, I'm assuming something is leaking a bit more than normal and has taken the main RCD to it's limit. I've left one circuit off that has a number of SMPSUs on it and so far all is stable again. Yes I will turn everything off and check the trip current of the1 RCD in case it has become overly sensitive, but NOT tonight! So my thought was to replace the main switch/RCD with a simple switch and then all of the MCBs with RCBOs, everything will be protected and in the event of a real problem I don't lose the whole darn house, just the one errant circuit. So is it a practical idea? I think so, but would welcome any thoughts, good or bad about doing it. I know the 17th edition suggests a split load CU, but that would still leave me with a 50/50% split and a gamble as to what worked and what didn't. I have 100% RCBOs (glad I did with the nusiance trips I had the other day!) I have Hager. Crabtree are (or were) a good brand. I would advise not putting all the larger RCBOs (32A rings, heaters) next to each other - apparantly localised heat build up is a problem. I left a 1 module gap every 2-3 on mine and the middle RCBO is a low current one (lights). You'll probably need 1 module RCBOs - they are a lot taller than an MCB. Is your CU tidy inside? In the worst case, you could replace your CU with a bigger one to give you more space. -- Tim Watts Personal Blog: http://squiddy.blog.dionic.net/ http://www.sensorly.com/ Crowd mapping of 2G/3G/4G mobile signal coverage |
Thoughts on fitting RCBOs
In article , Tim Watts
wrote: [Snip] Is your CU tidy inside? In the worst case, you could replace your CU with a bigger one to give you more space. The trouble with replacing the enclosure is that you have the incoming live & neutral to deal with. You can only isolate them by removing the "compnay" fuse. Years ago, before 'privatisation', I needed to repace my CU and arranged for someone to come and remove the company fuse. I said to him that I estimated it was a two hours job, if he came back and and reconnected me then, I could put the kettle on. He came back as suggested. Would that work these days? -- From KT24 Using a RISC OS computer running v5.18 |
Thoughts on fitting RCBOs
In message , Tim Watts
writes Thanks for the comments Tim and others, much appreciated.. I have 100% RCBOs (glad I did with the nusiance trips I had the other day!) I have Hager. Crabtree are (or were) a good brand. I would advise not putting all the larger RCBOs (32A rings, heaters) next to each other - apparantly localised heat build up is a problem. I left a 1 module gap every 2-3 on mine and the middle RCBO is a low current one (lights). Something that I hadn't considered, thank you for that. You'll probably need 1 module RCBOs - they are a lot taller than an MCB. MMMMMmmmmm I think that I shall have to start looking at spec's to see how the 2 sizes relate. Is your CU tidy inside? Relatively so, the spaghetti over to the right isn't as bad as it looks! Don't panic too much about the "telephone" cable, bottom right, it is the feed to the door bell. http://s117.photobucket.com/user/G8I...zps52f6bcf2.jp g.html In the worst case, you could replace your CU with a bigger one to give you more space. I am fortunate that the CU is mounted on a panel that in turn is mounted on 2" X 2" battens so there is a reasonable amount of space behind it, unfortunately many of the cables were bundled together when it was installed and trying to get a bit of slack to move them around may be difficult, but not impossible. My only restriction in size is that I cannot fit a longer unit, I would need to go for a second one above the existing one. -- Bill |
Thoughts on fitting RCBOs
charles wrote:
The trouble with replacing the enclosure is that you have the incoming live & neutral to deal with. You can only isolate them by removing the "compnay" fuse. Bill would appear to have a mains/generator changeover switch before the CU, so maybe that's less of an issue? |
Thoughts on fitting RCBOs
On Wed, 23 Oct 2013 23:27:02 +0100, bm wrote:
14 MCBs? Jesus H. Whats odd about that? The house has 14 spread across 4 RCDs in two CU's. This arrangment replaced 4 wire fuses for cooker, ring main (singular), lights (all) & garage. As to the question, individual RCBO's seems a bit excessive. Split load with some thought about what is "shared" will be just as effective against the nuisance trips caused by high overall leakage. -- Cheers Dave. |
Thoughts on fitting RCBOs
In message , charles
writes In article , Tim Watts wrote: [Snip] Is your CU tidy inside? In the worst case, you could replace your CU with a bigger one to give you more space. The trouble with replacing the enclosure is that you have the incoming live & neutral to deal with. You can only isolate them by removing the "compnay" fuse. Years ago, before 'privatisation', I needed to repace my CU and arranged for someone to come and remove the company fuse. I said to him that I estimated it was a two hours job, if he came back and and reconnected me then, I could put the kettle on. He came back as suggested. Would that work these days? Ah ha! There was some forward planning here, an unusual event in this house, as the CU is about 4m away from the meter and boards fuse, there is a 100A fused switch near to the meter so that I can isolate the CU. Plus the later addition of the generator transfer switch also gives the same option a bit closer to the CU. About 10 years ago my parents had a serious failure in their CU that meant it had to be replaced. I pulled the boards fuse and then phoned them afterwards to let them know why and to ask for it to be re-sealed. Despite many meter readers visits, so it must have been seen, it is still not sealed again. -- Bill |
Thoughts on fitting RCBOs
On Wed, 23 Oct 2013 23:20:47 +0100, Stephen wrote:
boiler & immersion Hum, so if a leakage fault develops in the immersion (fairly common) it trips off the heating... Remember N-E faults can trip and RCD, though I guess the immersion switch will be DP. Still makes it harder to work on one or the other independantly though. -- Cheers Dave. |
Thoughts on fitting RCBOs
In message , John
Rumm writes Hi John and others for your comments, all appreciated. Your experience adequately illustrates why the "whole house" RCD arrangement is deprecated - it was never a great idea, and the march of time (and things with leaky input filters) has only made the limitations more apparent. Indeed, filtering is all well and good, but causes lots of other issues. So is it a practical idea? Practical - yes certainly. Its the "Rolls Royce" solution that gives the best possible discrimination in the even of an earth fault. Obviously its more expensive than other options. Although cost is, obviously, a factor I feel it would be worth it to only lose one circuit in the event of a fault. I can only see things getting worse with more electronics making their way into homes and so more filtering, unless of course they are manufactured in a well known far East country where the various components are very obviously missing from the PSUs by the empty holes in the PCBs, Maybe that is an advantage of some of these dodgy imports??? There is no leakage from the filtering because they omitted it to save 5p per unit. But that is another discussion for another day... Split load does not have to mean a 50/50 split. Some 17th edition CUs may have say 4 RCDs and some unprotected (aka "high integrity") ways as well (for feeding circuits that meet the requirements for not being RCD protected). You can also arrange the split in various combinations of ways as suits your application. Yes, sorry, badly phrased on my part there. I should have just said split. Yes I am competent to do it, just nervous that I may have missed a fundamental flaw in the idea. If it matters the CU is a Crabtree Starbreaker with a single 80A switch/30mA RCD and 14 MCBs and a DIN mount bell transformer. Without checking I don't know if you can get single module wide RCBOs for this enclosure (and if so if there is really enough space to wire them). You may find you need to replace the enclosure as well. If no one puts me off the ideas I'm having then checking physical sizes is next on the agenda. Hopefully in the same enclosure, I'm not too worried about doing that. But if it came to a new enclosure then the panic will set in! Although there is plenty of space behind the CU, I would not look forward too much to replacing it. Apart from the cost, am I crazy? No, although you probably ought to look at some pragmatic options. You may find a combination of several RCDs covering a two or three circuits each, plus a smaller number of RCBOs would make for a system that is equally effective, but also leave more money to spend on improving other aspects of the system. To get a quick, ball park, idea of cost I checked on TLC's web site earlier and although scary I managed to not quite fall off my chair. So if it does come to it I'm hopeful to find a slightly cheaper route. I'm quite happy with the rest of the electrics in the house, all bar one slight anomaly which I can easily sort out, just waiting on a round tuit appearing. -- Bill |
Thoughts on fitting RCBOs
In article , Bill
writes While some of the genuine faults were a pain and time consuming to locate the SMPSUs are something I have to live with and they are taking my overall leakage too near the 30mA limit on the CU. Aren't you allowed to replace the RCD with a 100mA one in these circumstances? That would be cheaper than replacing the existing RCD and all the breakers. -- (\_/) (='.'=) (")_(") |
Thoughts on fitting RCBOs
On Thu, 24 Oct 2013 09:05:12 +0100, Mike Tomlinson wrote:
... they are taking my overall leakage too near the 30mA limit on the CU. Aren't you allowed to replace the RCD with a 100mA one in these circumstances? The RCD is for shock protection. Pretty sure that has to be 30 mA. 100mA ones are for circuit protection and normally time delayed to provide discrimination against downstream 30 mA shock protection RCDs. -- Cheers Dave. |
Thoughts on fitting RCBOs
On Thursday, 24 October 2013 08:05:49 UTC+1, charles wrote:
In article , Tim Watts wrote: [Snip] Is your CU tidy inside? In the worst case, you could replace your CU with a bigger one to give you more space. The trouble with replacing the enclosure is that you have the incoming live & neutral to deal with. You can only isolate them by removing the "compnay" fuse. Years ago, before 'privatisation', I needed to repace my CU and arranged for someone to come and remove the company fuse. I said to him that I estimated it was a two hours job, if he came back and and reconnected me then, I could put the kettle on. He came back as suggested. Would that work these days? I replaced my CU in 2005. EDF said I booking slots were 'morning' and 'evening'. I booked a disconnect and reconnect* for the morning, and connected an isolation switch with dangling tails. When the guy came round, slightly confused by the work request, I explained I wanted him to disconnect the old CU and reconnect to the isolation switch. He did it, but he was deeply unhappy about it, and came back in the evening so he could test it, which meant plugging in a socket tester. *ALL* he cared about was that I had phase and neutral the right way round (possibly what he was actually testing was that he'd connected them the right way round!). As far as I can see, if I'd had the isolation switch connected to a CU mounted somewhere random (but legal), connected to a single socket, he'd have been perfectly happy with my proposed arrangement - so that's what I'll do next time, particularly because then I'd have power while working on the old setup. * The hardest bit was actually booking it. After calling Powergen, then EDF, then Powergen, then EDF, I discovered the magic words 'disconnect' and 'reconnect', which enabled the person answering the phone to connect their brain to their fingers. They don't apparently have any idea what the words mean, so explaining what you want doesn't get you anywhere. |
Thoughts on fitting RCBOs
On Thursday 24 October 2013 08:05 charles wrote in uk.d-i-y:
In article , Tim Watts wrote: [Snip] Is your CU tidy inside? In the worst case, you could replace your CU with a bigger one to give you more space. The trouble with replacing the enclosure is that you have the incoming live & neutral to deal with. You can only isolate them by removing the "compnay" fuse. Years ago, before 'privatisation', I needed to repace my CU and arranged for someone to come and remove the company fuse. I said to him that I estimated it was a two hours job, if he came back and and reconnected me then, I could put the kettle on. He came back as suggested. Would that work these days? The might come back 6 hours later and charge you £35 - happened to me, with EDF. I installed an isolator in the meter box at the same time. -- Tim Watts Personal Blog: http://squiddy.blog.dionic.net/ http://www.sensorly.com/ Crowd mapping of 2G/3G/4G mobile signal coverage |
Thoughts on fitting RCBOs
On Thursday 24 October 2013 09:05 Mike Tomlinson wrote in uk.d-i-y:
In article , Bill writes While some of the genuine faults were a pain and time consuming to locate the SMPSUs are something I have to live with and they are taking my overall leakage too near the 30mA limit on the CU. Aren't you allowed to replace the RCD with a 100mA one in these circumstances? That would be cheaper than replacing the existing RCD and all the breakers. No. -- Tim Watts Personal Blog: http://squiddy.blog.dionic.net/ http://www.sensorly.com/ Crowd mapping of 2G/3G/4G mobile signal coverage |
Thoughts on fitting RCBOs
On Thursday 24 October 2013 09:50 Dave Liquorice wrote in uk.d-i-y:
On Thu, 24 Oct 2013 09:05:12 +0100, Mike Tomlinson wrote: ... they are taking my overall leakage too near the 30mA limit on the CU. Aren't you allowed to replace the RCD with a 100mA one in these circumstances? The RCD is for shock protection. Pretty sure that has to be 30 mA. Yes and I'm absolutely sure - not only 30mA trip, but 40mS disconenct time (at 5x30mA fault IIRC, but in practise, all of mine trip 40mS at 1x30mA fault). 100mA ones are for circuit protection and normally time delayed to provide discrimination against downstream 30 mA shock protection RCDs. -- Tim Watts Personal Blog: http://squiddy.blog.dionic.net/ http://www.sensorly.com/ Crowd mapping of 2G/3G/4G mobile signal coverage |
Thoughts on fitting RCBOs
On 24/10/2013 08:45, Bill wrote:
In message , John Rumm writes Hi John and others for your comments, all appreciated. Your experience adequately illustrates why the "whole house" RCD arrangement is deprecated - it was never a great idea, and the march of time (and things with leaky input filters) has only made the limitations more apparent. Indeed, filtering is all well and good, but causes lots of other issues. So is it a practical idea? Practical - yes certainly. Its the "Rolls Royce" solution that gives the best possible discrimination in the even of an earth fault. Obviously its more expensive than other options. Although cost is, obviously, a factor I feel it would be worth it to only lose one circuit in the event of a fault. I can only see things getting worse with more electronics making their way into homes and so more filtering, unless of course they are manufactured in a well known far East country where the various components are very obviously missing from the PSUs by the empty holes in the PCBs, Maybe that is an advantage of some of these dodgy imports??? There is no leakage from the filtering because they omitted it to save 5p per unit. But that is another discussion for another day... Split load does not have to mean a 50/50 split. Some 17th edition CUs may have say 4 RCDs and some unprotected (aka "high integrity") ways as well (for feeding circuits that meet the requirements for not being RCD protected). You can also arrange the split in various combinations of ways as suits your application. Yes, sorry, badly phrased on my part there. I should have just said split. Yes I am competent to do it, just nervous that I may have missed a fundamental flaw in the idea. If it matters the CU is a Crabtree Starbreaker with a single 80A switch/30mA RCD and 14 MCBs and a DIN mount bell transformer. Without checking I don't know if you can get single module wide RCBOs for this enclosure (and if so if there is really enough space to wire them). You may find you need to replace the enclosure as well. If no one puts me off the ideas I'm having then checking physical sizes is next on the agenda. Hopefully in the same enclosure, I'm not too worried about doing that. But if it came to a new enclosure then the panic will set in! Although there is plenty of space behind the CU, I would not look forward too much to replacing it. Something to keep in mind is that its more difficult to wire a box full of RCBOs unless the wiring is very tidy. So you may well be faced with needing to pretty much "start again" anyway to have a hope of getting it all neatly dressed in the box. Hence the effort difference between keeping the box and installing a new one may be less than you expect. No, although you probably ought to look at some pragmatic options. You may find a combination of several RCDs covering a two or three circuits each, plus a smaller number of RCBOs would make for a system that is equally effective, but also leave more money to spend on improving other aspects of the system. To get a quick, ball park, idea of cost I checked on TLC's web site earlier and although scary I managed to not quite fall off my chair. So if it does come to it I'm hopeful to find a slightly cheaper route. You could probably find a solution that just uses three or four RCBOs, and then two or three normal RCDs that in practice will work just as well. Just identify which circuits are likely to be high leakage (lots of IT kit, mineral insulated heating elements, water in proximity etc), stuff that is liable to genuine earth fault (circuits outside, socket circuits), and then "other" which is low leakage and risk - lighting, smoke alarms etc. I'm quite happy with the rest of the electrics in the house, all bar one slight anomaly which I can easily sort out, just waiting on a round tuit appearing. TLC might have em ;-) -- Cheers, John. /================================================== ===============\ | Internode Ltd - http://www.internode.co.uk | |-----------------------------------------------------------------| | John Rumm - john(at)internode(dot)co(dot)uk | \================================================= ================/ |
Thoughts on fitting RCBOs
On 24/10/2013 08:17, Bill wrote:
In message , Tim Watts writes Is your CU tidy inside? Relatively so, the spaghetti over to the right isn't as bad as it looks! Don't panic too much about the "telephone" cable, bottom right, it is the feed to the door bell. http://s117.photobucket.com/user/G8I...zps52f6bcf2.jp g.html There's not much spare height there for single module RCBOs... In the worst case, you could replace your CU with a bigger one to give you more space. I am fortunate that the CU is mounted on a panel that in turn is mounted on 2" X 2" battens so there is a reasonable amount of space behind it, unfortunately many of the cables were bundled together when it was installed and trying to get a bit of slack to move them around may be difficult, but not impossible. My only restriction in size is that I cannot fit a longer unit, I would need to go for a second one above the existing one. You may have to crimp extensions onto some of the circuit ends... especially if the neutrals have been cut shorter than the lives (they both need to reach the RCBO) -- Cheers, John. /================================================== ===============\ | Internode Ltd - http://www.internode.co.uk | |-----------------------------------------------------------------| | John Rumm - john(at)internode(dot)co(dot)uk | \================================================= ================/ |
Thoughts on fitting RCBOs
On 24/10/2013 09:05, Mike Tomlinson wrote:
In article , Bill writes While some of the genuine faults were a pain and time consuming to locate the SMPSUs are something I have to live with and they are taking my overall leakage too near the 30mA limit on the CU. Aren't you allowed to replace the RCD with a 100mA one in these circumstances? No now. There may have been times in the past where that was appropriate - but only where the RCD was there to protect the circuit and reduce fire risk, not if its purpose was shock protection. That would be cheaper than replacing the existing RCD and all the breakers. It would only be fixing a symptom rather than the actual problem. It would also mean you no longer have adequate shock protection on the circuits that really need it. -- Cheers, John. /================================================== ===============\ | Internode Ltd - http://www.internode.co.uk | |-----------------------------------------------------------------| | John Rumm - john(at)internode(dot)co(dot)uk | \================================================= ================/ |
Thoughts on fitting RCBOs
On Thursday, October 24, 2013 8:23:49 AM UTC+1, Bill wrote:
Despite many meter readers visits, so it must have been seen, it is still not sealed again. They don't seem bothered any more. I had a CU replaced a few years ago and they cut the seal and pulled the EB fuse but nobody has commented on it being missing. Do they have some fancy way of detecting meter bypasses these days? Robert |
Thoughts on fitting RCBOs
In article o.uk,
Dave Liquorice writes The RCD is for shock protection. Pretty sure that has to be 30 mA. 100mA ones are for circuit protection and normally time delayed to provide discrimination against downstream 30 mA shock protection RCDs. Ta. We had a computer suite with ~15 PCs which regularly tripped the 30mA RCD feeding the room. I'm pretty sure the sparky's fix was to change the 30mA RCD for a 100mA one. -- (\_/) (='.'=) (")_(") |
Thoughts on fitting RCBOs
On Thursday 24 October 2013 15:44 Mike Tomlinson wrote in uk.d-i-y:
In article o.uk, Dave Liquorice writes The RCD is for shock protection. Pretty sure that has to be 30 mA. 100mA ones are for circuit protection and normally time delayed to provide discrimination against downstream 30 mA shock protection RCDs. Ta. We had a computer suite with ~15 PCs which regularly tripped the 30mA RCD feeding the room. I'm pretty sure the sparky's fix was to change the 30mA RCD for a 100mA one. That's allowed (I think!) because it is a non domestic installation. -- Tim Watts Personal Blog: http://squiddy.blog.dionic.net/ http://www.sensorly.com/ Crowd mapping of 2G/3G/4G mobile signal coverage |
Thoughts on fitting RCBOs
In message ,
RobertL writes On Thursday, October 24, 2013 8:23:49 AM UTC+1, Bill wrote: Despite many meter readers visits, so it must have been seen, it is still not sealed again. They don't seem bothered any more. I had a CU replaced a few years ago and they cut the seal and pulled the EB fuse but nobody has commented on it being missing. In these days of out-sourced meter readers etc. they probably don't care -- Chris French |
Thoughts on fitting RCBOs
On 24/10/2013 08:45, Bill wrote:
SNIP If no one puts me off the ideas I'm having then checking physical sizes is next on the agenda. Hopefully in the same enclosure, I'm not too worried about doing that. But if it came to a new enclosure then the panic will set in! Although there is plenty of space behind the CU, I would not look forward too much to replacing it. I am assuming that this is a plastic enclosure? If so is the pull down cover for the MCBs in the middle vertically or much nearer the bottom than the top? The reason I ask is that I've looked at this and all the Starbreakers I see online have the door low down and can take RCBOs with no problem (although they have to be Crabtree ones, as they plug into the busbar and are not of conventional design) - my own on the other hand has the door in the middle and I don't think that there is enough room for RCBOs. SteveW |
Thoughts on fitting RCBOs
On 24/10/2013 18:01, SteveW wrote:
On 24/10/2013 08:45, Bill wrote: SNIP If no one puts me off the ideas I'm having then checking physical sizes is next on the agenda. Hopefully in the same enclosure, I'm not too worried about doing that. But if it came to a new enclosure then the panic will set in! Although there is plenty of space behind the CU, I would not look forward too much to replacing it. I am assuming that this is a plastic enclosure? If so is the pull down cover for the MCBs in the middle vertically or much nearer the bottom than the top? The reason I ask is that I've looked at this and all the Starbreakers I see online have the door low down and can take RCBOs with no problem (although they have to be Crabtree ones, as they plug into the busbar and are not of conventional design) - my own on the other hand has the door in the middle and I don't think that there is enough room for RCBOs. SteveW Ah, couldn't get the photo to work before, now I've seen it, it is the version that will take RCBOs. SteveW |
Thoughts on fitting RCBOs
Bill wrote:
Hi all, especially the knowledgeable electricians on here. What are your thoughts on me replacing all of the MCBs in my CU with RCBOs? At present I have 14 MCBs all protected by one 30mA RCD main switch. Over the last few years I've had tripping problems from a trapped L to E fault in a metal clad light unit, it too 10 years before this became a problem! Water blowing into an extractor fan, water in an outside light and the big issue of too many switch mode PSUs in the house. While some of the genuine faults were a pain and time consuming to locate the SMPSUs are something I have to live with and they are taking my overall leakage too near the 30mA limit on the CU. This has been brought to a head by a few trips this evening, no one circuit being the culprit, leave any 2 or 3 MCBs off and it is happy, just not happy with all on, I'm assuming something is leaking a bit more than normal and has taken the main RCD to it's limit. I've left one circuit off that has a number of SMPSUs on it and so far all is stable again. Yes I will turn everything off and check the trip current of the1 RCD in case it has become overly sensitive, but NOT tonight! So my thought was to replace the main switch/RCD with a simple switch and then all of the MCBs with RCBOs, everything will be protected and in the event of a real problem I don't lose the whole darn house, just the one errant circuit. So is it a practical idea? I think so, but would welcome any thoughts, good or bad about doing it. I know the 17th edition suggests a split load CU, but that would still leave me with a 50/50% split and a gamble as to what worked and what didn't. Yes I am competent to do it, just nervous that I may have missed a fundamental flaw in the idea. If it matters the CU is a Crabtree Starbreaker with a single 80A switch/30mA RCD and 14 MCBs and a DIN mount bell transformer. Apart from the cost, am I crazy? Bill. Whip off the front cover and take a photo of the inside of the CU. That looks like the SB6000 and you cannot get single module RCBOs for that model. And it would be cheaper to replace the CU considering Crabtrees prices. -- Adam |
Thoughts on fitting RCBOs
chris French wrote:
In message , RobertL writes On Thursday, October 24, 2013 8:23:49 AM UTC+1, Bill wrote: Despite many meter readers visits, so it must have been seen, it is still not sealed again. They don't seem bothered any more. I had a CU replaced a few years ago and they cut the seal and pulled the EB fuse but nobody has commented on it being missing. In these days of out-sourced meter readers etc. they probably don't care ****ing did care when they turned up and they could see that I had connected straight into a cut out without a meter:-) -- Adam |
Thoughts on fitting RCBOs
In message , John
Rumm writes I am fortunate that the CU is mounted on a panel that in turn is mounted on 2" X 2" battens so there is a reasonable amount of space behind it, unfortunately many of the cables were bundled together when it was installed and trying to get a bit of slack to move them around may be difficult, but not impossible. My only restriction in size is that I cannot fit a longer unit, I would need to go for a second one above the existing one. You may have to crimp extensions onto some of the circuit ends... especially if the neutrals have been cut shorter than the lives (they both need to reach the RCBO) I am reminded of a photo that surfaces on here occasionally of some ones install where they fitted a separate DIN rail box and then patched into the CU, an exceptionally neat job. But yes, I had worried about that, fortunately I use crimps a lot and I'm quite used to them, they will take up a bit of space and aren't very flexible though. Unless I do them behind the board maybe? -- Bill |
Thoughts on fitting RCBOs
In message , ARW
writes If it matters the CU is a Crabtree Starbreaker with a single 80A switch/30mA RCD and 14 MCBs and a DIN mount bell transformer. Apart from the cost, am I crazy? Bill. Whip off the front cover and take a photo of the inside of the CU. That looks like the SB6000 and you cannot get single module RCBOs for that model. And it would be cheaper to replace the CU considering Crabtrees prices. There should be one at http://s117.photobucket.com/user/G8I...zps52f6bcf2.jp g.html If I do end up having to use something else do you recommend any one in particular? -- Bill |
Thoughts on fitting RCBOs
In message , Bill
writes In message , John Rumm writes I am fortunate that the CU is mounted on a panel that in turn is mounted on 2" X 2" battens so there is a reasonable amount of space behind it, unfortunately many of the cables were bundled together when it was installed and trying to get a bit of slack to move them around may be difficult, but not impossible. My only restriction in size is that I cannot fit a longer unit, I would need to go for a second one above the existing one. You may have to crimp extensions onto some of the circuit ends... especially if the neutrals have been cut shorter than the lives (they both need to reach the RCBO) I am reminded of a photo that surfaces on here occasionally of some ones install where they fitted a separate DIN rail box and then patched into the CU, an exceptionally neat job. sounds like Anndrew Gabriel's -- Chris French |
Thoughts on fitting RCBOs
On 24/10/2013 18:17, ARW wrote:
Bill wrote: Hi all, especially the knowledgeable electricians on here. What are your thoughts on me replacing all of the MCBs in my CU with RCBOs? At present I have 14 MCBs all protected by one 30mA RCD main switch. Over the last few years I've had tripping problems from a trapped L to E fault in a metal clad light unit, it too 10 years before this became a problem! Water blowing into an extractor fan, water in an outside light and the big issue of too many switch mode PSUs in the house. While some of the genuine faults were a pain and time consuming to locate the SMPSUs are something I have to live with and they are taking my overall leakage too near the 30mA limit on the CU. This has been brought to a head by a few trips this evening, no one circuit being the culprit, leave any 2 or 3 MCBs off and it is happy, just not happy with all on, I'm assuming something is leaking a bit more than normal and has taken the main RCD to it's limit. I've left one circuit off that has a number of SMPSUs on it and so far all is stable again. Yes I will turn everything off and check the trip current of the1 RCD in case it has become overly sensitive, but NOT tonight! So my thought was to replace the main switch/RCD with a simple switch and then all of the MCBs with RCBOs, everything will be protected and in the event of a real problem I don't lose the whole darn house, just the one errant circuit. So is it a practical idea? I think so, but would welcome any thoughts, good or bad about doing it. I know the 17th edition suggests a split load CU, but that would still leave me with a 50/50% split and a gamble as to what worked and what didn't. Yes I am competent to do it, just nervous that I may have missed a fundamental flaw in the idea. If it matters the CU is a Crabtree Starbreaker with a single 80A switch/30mA RCD and 14 MCBs and a DIN mount bell transformer. Apart from the cost, am I crazy? Bill. Whip off the front cover and take a photo of the inside of the CU. That looks like the SB6000 and you cannot get single module RCBOs for that model. And it would be cheaper to replace the CU considering Crabtrees prices. And Denmans do good value Bundle deals.... you can get a 10 or 14 way Curve CU with your choice of 10 RCBOs for around 100 quid plus vat. |
Thoughts on fitting RCBOs
On 24/10/2013 08:05, charles wrote:
In article , Tim Watts wrote: [Snip] Is your CU tidy inside? In the worst case, you could replace your CU with a bigger one to give you more space. The trouble with replacing the enclosure is that you have the incoming live & neutral to deal with. You can only isolate them by removing the "compnay" fuse. Years ago, before 'privatisation', I needed to repace my CU and arranged for someone to come and remove the company fuse. I said to him that I estimated it was a two hours job, if he came back and and reconnected me then, I could put the kettle on. He came back as suggested. Would that work these days? When I moved in the seal was already broken on the main incomer. So while doing some electrical work which required me to pull the main fuse I also fitted a DP isolator (to the meter board) and then replaced the fuse + broken seal (still broken). A few years later we had a meter replacement. The chappie didn't even mention the broken seal, replaced the meter (still connected in my isolator) and then resealed the main fuse. |
Thoughts on fitting RCBOs
On 23/10/2013 23:27, bm wrote:
On 23/10/2013 22:50, Bill wrote: Hi all, especially the knowledgeable electricians on here. What are your thoughts on me replacing all of the MCBs in my CU with RCBOs? At present I have 14 MCBs all protected by one 30mA RCD main switch. Over the last few years I've had tripping problems from a trapped L to E fault in a metal clad light unit, it too 10 years before this became a problem! Water blowing into an extractor fan, water in an outside light and the big issue of too many switch mode PSUs in the house. While some of the genuine faults were a pain and time consuming to locate the SMPSUs are something I have to live with and they are taking my overall leakage too near the 30mA limit on the CU. snip Apart from the cost, am I crazy? 14 MCBs? Jesus H. :D I wanted a high level of discrimination. thats why the outside lights are on their own RCBO, the outside sockets are on their own RCBO. That way I don't care if any faults develop outside as it wont affect the rest of the house. Similar reasoning for the smoke dets co dets, heat dets and alarm system being on their own RCBO, that way any faults elsewhere do not then affect H&S or flatten the standby batteries. SImilar reasoning for teh boiler being on its own RCBO. it won't get affected by any faults elsewhere in teh house, and during winter with a frost protection device, prevent the pipes from freezing and the house then flooding. So I ended up with whats called a high integrity CU. |
Thoughts on fitting RCBOs
Split load does not have to mean a 50/50 split. Some 17th edition CUs may have say 4 RCDs and some unprotected (aka "high integrity") ways as well (for feeding circuits that meet the requirements for not being RCD protected). You can also arrange the split in various combinations of ways as suits your application. One thing to bear in mind. a single RCD will take at least the same width as two or possibly 3 MCBs. WIth 4 RCD's you're loosing space for for your MCB's. The beauty of a RCBO is that in the same width as a single MCB, you are combining RCD and MCB functionality in one. So with a 19 module wide CU, two is taken up with 2 pole isolator, leaving you with 17 spare ways. you can then either fit: (a) 4 RCDs (assume double width so thats 8 ways taken) and then up to 9 MCBs for up to 9 circuits, and still have the issue of 2 or more circuits losing power when 1 RCD trips. or (b) fit up to 17 RCBO's, have up to 17 circuits and if any one RCBO trips, only one circuit is affected, leaving the rest alone. I know which I'd prefer..... :-) Yes I am competent to do it, just nervous that I may have missed a fundamental flaw in the idea. The things in my limited experience is that: You need to ensure that your choice of CU *can* accommodate RCBOs It often helps if you use the same make for both teh CU and the RCBOs. If it matters the CU is a Crabtree Starbreaker with a single 80A switch/30mA RCD and 14 MCBs and a DIN mount bell transformer. Without checking I don't know if you can get single module wide RCBOs for this enclosure (and if so if there is really enough space to wire them). You may find you need to replace the enclosure as well. Apart from the cost, am I crazy? No, although you probably ought to look at some pragmatic options. You may find a combination of several RCDs covering a two or three circuits each, plus a smaller number of RCBOs would make for a system that is equally effective, but also leave more money to spend on improving other aspects of the system. |
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