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How Can This Happen (Electrical)?
In one bedroom we have a ceiling fan supplied from the lighting circuit.
It's been there for over 10 years no problems. In the past few nights a couple of times when switching it off the RCD protecting the ring mains has tripped. But the lighting circuits don't go through it and the lights are still on including the one which is part of the fan and the fan itself can be switched back on. Puzzled as to how this can happen - and where to start looking. -- bert |
How Can This Happen (Electrical)?
On 28/02/2019 12:21, bert wrote:
In one bedroom we have a ceiling fan supplied from the lighting circuit. It's been there for over 10 years no problems. In the past few nights a couple of times when switching it off the RCD protecting the ring mains has tripped. But the lighting circuits don't go through it and the lights are still on including the one which is part of the fan and the fan itself can be switched back on. Puzzled as to how this can happen - and where to start looking. Possibly a suppressor in the motor has failed and the resulting inductive spike is coupling into an adjacent circuit. Makes sense as you say it doesn't always happen, probably only when the voltage happens to be on a high part of the AC cycle. Cheers -- Clive |
How Can This Happen (Electrical)?
"Tim+" wrote in message
... bert Wrote in message: In one bedroom we have a ceiling fan supplied from the lighting circuit. It's been there for over 10 years no problems.In the past few nights a couple of times when switching it off the RCD protecting the ring mains has tripped. But the lighting circuits don't go through it and the lights are still on including the one which is part of the fan and the fan itself can be switched back on.Puzzled as to how this can happen - and where to start looking.-- bert It would suggest that it's not supplied by the lighting circuit... Are you sure that your RCD *only* protects the ring mains and not *all* circuits such as cooker, lighting in addition to ring mains? My understanding is that an RCD in the "fuse box" is usually upstream of the ring main MCBs (over-current sensors, equivalent to wire fuses) and protects the whole house. Our previous house had two RCDs: one was a separate unit that was between the meter and the fuse box, and the other was within the fuse box. Even if the RCD within the fuse box was tripped, all power went off, including to non-ring-main circuits such as lighting and cooker. What happens if you manually turn off the RCD? Does the lighting still continue working? |
How Can This Happen (Electrical)?
On Thu, 28 Feb 2019 12:21:12 +0000, bert wrote:
In one bedroom we have a ceiling fan supplied from the lighting circuit. It's been there for over 10 years no problems. In the past few nights a couple of times when switching it off the RCD protecting the ring mains has tripped. But the lighting circuits don't go through it and the lights are still on including the one which is part of the fan and the fan itself can be switched back on. Puzzled as to how this can happen - and where to start looking. Earthed via a the ring-main circuit? -- Regards, Paul Herber http://www.paulherber.co.uk/ |
How Can This Happen (Electrical)?
On 28/02/2019 14:15, Paul Herber wrote:
On Thu, 28 Feb 2019 12:21:12 +0000, bert wrote: In one bedroom we have a ceiling fan supplied from the lighting circuit. It's been there for over 10 years no problems. In the past few nights a couple of times when switching it off the RCD protecting the ring mains has tripped. But the lighting circuits don't go through it and the lights are still on including the one which is part of the fan and the fan itself can be switched back on. Puzzled as to how this can happen - and where to start looking. Earthed via a the ring-main circuit? Probably not, RCDs don't just detect earth leakage but any current imbalance between live and neutral. It wouldn't actually matter where it was earthed if there was leakage to earth and it wouldn't affect other circuit unless they also had an earth leakage problem as RCDs aren't connect to earth. |
How Can This Happen (Electrical)?
On 28/02/2019 14:38, dennis@home wrote:
On 28/02/2019 14:15, Paul Herber wrote: On Thu, 28 Feb 2019 12:21:12 +0000, bert wrote: In one bedroom we have a ceiling fan supplied from the lighting circuit. It's been there for over 10 years no problems. In the past few nights a couple of times when switching it off the RCD protecting the ring mains has tripped. But the lighting circuits don't go through it and the lights are still on including the one which is part of the fan and the fan itself can be switched back on. Puzzled as to how this can happen - and where to start looking. Earthed via a the ring-main circuit? Probably not, RCDs don't just detect earth leakage but any current imbalance between live and neutral. It wouldn't actually matter where it was earthed if there was leakage to earth and it wouldn't affect other circuit unless they also had an earth leakage problem as RCDs aren't connect to earth. Quite agree. I think Clive is probably right as to the cause. Within the consumer unit, all the lives and all the neutrals are connected together, so there's scope for some coupling between circuits. The only thing that's really surprising (to me) is that the RCD protecting the lighting circuit does not trip. (I may be making a fool of myself here. Hope not!) |
How Can This Happen (Electrical)?
On 28/02/2019 15:00, GB wrote:
On 28/02/2019 14:38, dennis@home wrote: On 28/02/2019 14:15, Paul Herber wrote: On Thu, 28 Feb 2019 12:21:12 +0000, bert wrote: In one bedroom we have a ceiling fan supplied from the lighting circuit. It's been there for over 10 years no problems. In the past few nights a couple of times when switching it off the RCD protecting the ring mains has tripped. But the lighting circuits don't go through it and the lights are still on including the one which is part of the fan and the fan itself can be switched back on. Puzzled as to how this can happen - and where to start looking. Earthed via a the ring-main circuit? Probably not, RCDs don't just detect earth leakage but any current imbalance between live and neutral. It wouldn't actually matter where it was earthed if there was leakage to earth and it wouldn't affect other circuit unless they also had an earth leakage problem as RCDs aren't connect to earth. Quite agree. I think Clive is probably right as to the cause. Within the consumer unit, all the lives and all the neutrals are connected together, so there's scope for some coupling between circuits. The only thing that's really surprising (to me) is that the RCD protecting the lighting circuit does not trip. I wouldn't assume there there is an RCD protecting the lighting circuit. Very many homes don't have them. (I may be making a fool of myself here. Hope not!) -- Robin reply-to address is (intended to be) valid |
How Can This Happen (Electrical)?
On Thursday, 28 February 2019 12:26:10 UTC, bert wrote:
In one bedroom we have a ceiling fan supplied from the lighting circuit. It's been there for over 10 years no problems. In the past few nights a couple of times when switching it off the RCD protecting the ring mains has tripped. But the lighting circuits don't go through it and the lights are still on including the one which is part of the fan and the fan itself can be switched back on. Puzzled as to how this can happen - and where to start looking. -- bert Neutral-Earth faults can trip the RCD. |
How Can This Happen (Electrical)?
"Tim+" wrote in message ... bert Wrote in message: In one bedroom we have a ceiling fan supplied from the lighting circuit. It's been there for over 10 years no problems.In the past few nights a couple of times when switching it off the RCD protecting the ring mains has tripped. But the lighting circuits don't go through it and the lights are still on including the one which is part of the fan and the fan itself can be switched back on.Puzzled as to how this can happen - and where to start looking.-- bert It would suggest that it's not supplied by the lighting circuit... Doesn't explain why it can be switched on again when the RCD trips. |
How Can This Happen (Electrical)?
On 28/02/2019 16:44, Robin wrote:
On 28/02/2019 15:00, GB wrote: On 28/02/2019 14:38, dennis@home wrote: On 28/02/2019 14:15, Paul Herber wrote: On Thu, 28 Feb 2019 12:21:12 +0000, bert wrote: In one bedroom we have a ceiling fan supplied from the lighting circuit. It's been there for over 10 years no problems. In the past few nights a couple of times when switching it off the RCD protecting the ring mains has tripped. But the lighting circuits don't go through it and the lights are still on including the one which is part of the fan and the fan itself can be switched back on. Puzzled as to how this can happen - and where to start looking. Earthed via a the ring-main circuit? Probably not, RCDs don't just detect earth leakage but any current imbalance between live and neutral. It wouldn't actually matter where it was earthed if there was leakage to earth and it wouldn't affect other circuit unless they also had an earth leakage problem as RCDs aren't connect to earth. Quite agree. I think Clive is probably right as to the cause. Within the consumer unit, all the lives and all the neutrals are connected together, so there's scope for some coupling between circuits. The only thing that's really surprising (to me) is that the RCD protecting the lighting circuit does not trip. I wouldn't assume there there is an RCD protecting the lighting circuit. Â*Very many homes don't have them. Of course the 18th edition has altered that for future installs (I think you are correct about the OPs lights) Just for info and not related to the OPs question. Domestic properties are now required to have RCD protection on the lighting circuits even if the cables are run in a manner or of the type that would not require RCD protection (eg in trunking or SWA) -- Adam |
How Can This Happen (Electrical)?
On 28/02/2019 18:02, ARW wrote:
On 28/02/2019 16:44, Robin wrote: On 28/02/2019 15:00, GB wrote: On 28/02/2019 14:38, dennis@home wrote: On 28/02/2019 14:15, Paul Herber wrote: On Thu, 28 Feb 2019 12:21:12 +0000, bert wrote: In one bedroom we have a ceiling fan supplied from the lighting circuit. It's been there for over 10 years no problems. In the past few nights a couple of times when switching it off the RCD protecting the ring mains has tripped. But the lighting circuits don't go through it and the lights are still on including the one which is part of the fan and the fan itself can be switched back on. Puzzled as to how this can happen - and where to start looking. Earthed via a the ring-main circuit? Probably not, RCDs don't just detect earth leakage but any current imbalance between live and neutral. It wouldn't actually matter where it was earthed if there was leakage to earth and it wouldn't affect other circuit unless they also had an earth leakage problem as RCDs aren't connect to earth. Quite agree. I think Clive is probably right as to the cause. Within the consumer unit, all the lives and all the neutrals are connected together, so there's scope for some coupling between circuits. The only thing that's really surprising (to me) is that the RCD protecting the lighting circuit does not trip. I wouldn't assume there there is an RCD protecting the lighting circuit. Â*Â*Very many homes don't have them. Of course the 18th edition has altered that for future installs (I think you are correct about the OPs lights) Is that on the basis that it's okay to get electrocuted by the lighting circuit? Perhaps it's a more refined way to die. Just for info and not related to the OPs question. Domestic properties are now required to have RCD protection on the lighting circuits even if the cables are run in a manner or of the type that would not require RCD protection (eg in trunking or SWA) -- Adam |
How Can This Happen (Electrical)?
Where is the switch for the fan, in the fan/light itself?
I'd start there. Brian -- ----- -- This newsgroup posting comes to you directly from... The Sofa of Brian Gaff... Blind user, so no pictures please Note this Signature is meaningless.! "bert" wrote in message ... In one bedroom we have a ceiling fan supplied from the lighting circuit. It's been there for over 10 years no problems. In the past few nights a couple of times when switching it off the RCD protecting the ring mains has tripped. But the lighting circuits don't go through it and the lights are still on including the one which is part of the fan and the fan itself can be switched back on. Puzzled as to how this can happen - and where to start looking. -- bert |
How Can This Happen (Electrical)?
I was thinking of back EMF.
That could make it back through the lights to the other circuits as a spike of some kind. Brian -- ----- -- This newsgroup posting comes to you directly from... The Sofa of Brian Gaff... Blind user, so no pictures please Note this Signature is meaningless.! "Tim+" wrote in message ... bert Wrote in message: In one bedroom we have a ceiling fan supplied from the lighting circuit. It's been there for over 10 years no problems.In the past few nights a couple of times when switching it off the RCD protecting the ring mains has tripped. But the lighting circuits don't go through it and the lights are still on including the one which is part of the fan and the fan itself can be switched back on.Puzzled as to how this can happen - and where to start looking.-- bert It would suggest that it's not supplied by the lighting circuit... Tim -- Please don't feed the trolls |
How Can This Happen (Electrical)?
On 28/02/2019 18:12, GB wrote:
On 28/02/2019 18:02, ARW wrote: Of course the 18th edition has altered that for future installs (I think you are correct about the OPs lights) Is that on the basis that it's okay to get electrocuted by the lighting circuit? Perhaps it's a more refined way to die. Lighting circuits have generally been classed as safe without RCD protection. For some reason domestic lighting circuits they are now unsafe without RCD protection. The RCD, when it first came into general use was for outside sockets and using the lawnmower etc. Remember the RCD 13A plug in breakers before RCDs were common place in CUs? -- Adam |
How Can This Happen (Electrical)?
On 28/02/2019 18:12, GB wrote:
On 28/02/2019 18:02, ARW wrote: On 28/02/2019 16:44, Robin wrote: On 28/02/2019 15:00, GB wrote: On 28/02/2019 14:38, dennis@home wrote: On 28/02/2019 14:15, Paul Herber wrote: On Thu, 28 Feb 2019 12:21:12 +0000, bert wrote: In one bedroom we have a ceiling fan supplied from the lighting circuit. It's been there for over 10 years no problems. In the past few nights a couple of times when switching it off the RCD protecting the ring mains has tripped. But the lighting circuits don't go through it and the lights are still on including the one which is part of the fan and the fan itself can be switched back on. Puzzled as to how this can happen - and where to start looking. Earthed via a the ring-main circuit? Probably not, RCDs don't just detect earth leakage but any current imbalance between live and neutral. It wouldn't actually matter where it was earthed if there was leakage to earth and it wouldn't affect other circuit unless they also had an earth leakage problem as RCDs aren't connect to earth. Quite agree. I think Clive is probably right as to the cause. Within the consumer unit, all the lives and all the neutrals are connected together, so there's scope for some coupling between circuits. The only thing that's really surprising (to me) is that the RCD protecting the lighting circuit does not trip. I wouldn't assume there there is an RCD protecting the lighting circuit. Â*Â*Very many homes don't have them. Of course the 18th edition has altered that for future installs (I think you are correct about the OPs lights) Is that on the basis that it's okay to get electrocuted by the lighting circuit? Perhaps it's a more refined way to die. It used to be on the basis of cost-effectiveness: the number of death and serious injuries from lighting circuits was much less than from sockets, showers, cookers etc. I have no idea if the cost-effectiveness has changed with cheaper RCDs (bearing in mind there are also now safer light fittings and less need to change bulbs) as those who decided such things don't see fit to publish their assessments of costs and benefits of changes - if they even bother to make them rather than going with what they just know makes sense. -- Robin reply-to address is (intended to be) valid |
How Can This Happen (Electrical)?
On 28/02/2019 18:36, ARW wrote:
The RCD, when it first came into general use was for outside sockets and using the lawnmower etc. Remember the RCD 13A plug in breakers before RCDs were common place in CUs? I still have a plug-in RCD which I use when working outside. It started off as 30mA but now reliably trips with less than 10mA so usually saves me a walk to the CU. I only wish we could such in the UK (as I think someone raised here before). -- Robin reply-to address is (intended to be) valid |
How Can This Happen (Electrical)?
On 28/02/2019 18:36, ARW wrote:
On 28/02/2019 18:12, GB wrote: On 28/02/2019 18:02, ARW wrote: Of course the 18th edition has altered that for future installs (I think you are correct about the OPs lights) Is that on the basis that it's okay to get electrocuted by the lighting circuit? Perhaps it's a more refined way to die. Lighting circuits have generally been classed as safe without RCD protection. For some reason domestic lighting circuits they are now unsafe without RCD protection. The RCD, when it first came into general use was for outside sockets and using the lawnmower etc. Remember the RCD 13A plug in breakers before RCDs were common place in CUs? Our CU was replaced in 1998, and no RCDs for us. We have a couple of those RCD adapters. I have no idea whether they work, though, as they've never tripped. The CU looks like one of these: https://www.screwfix.com/p/crabtree-...mer-unit/5823p But it must be the 1998 version. There are 11 ways in use. Do you think I can fit a couple of RCDs in? |
How Can This Happen (Electrical)?
On 28/02/2019 18:57, GB wrote:
On 28/02/2019 18:36, ARW wrote: On 28/02/2019 18:12, GB wrote: On 28/02/2019 18:02, ARW wrote: Of course the 18th edition has altered that for future installs (I think you are correct about the OPs lights) Is that on the basis that it's okay to get electrocuted by the lighting circuit? Perhaps it's a more refined way to die. Lighting circuits have generally been classed as safe without RCD protection. For some reason domestic lighting circuits they are now unsafe without RCD protection. The RCD, when it first came into general use was for outside sockets and using the lawnmower etc. Remember the RCD 13A plug in breakers before RCDs were common place in CUs? Our CU was replaced in 1998, and no RCDs for us. We have a couple of those RCD adapters. I have no idea whether they work, though, as they've never tripped. The CU looks like one of these: https://www.screwfix.com/p/crabtree-...mer-unit/5823p But it must be the 1998 version. There are 11 ways in use. Do you think I can fit a couple of RCDs in? If the Starbreaker has the plug in MCBs it may be possible to fit a couple of RCBOs. I was fitting RCD CUs well before 1998. A photo of your actual CU will help me decide if you can fit an RCBO (height restrictions apply). As for your plug in RCD breakers. They should have a test button. This is nothing more than a switch to imbalance the load via a resistor. It will not tell you if the RCD is tripping within the required times but it will give you a guide as to it's ability to work. -- Adam |
How Can This Happen (Electrical)?
On 28/02/2019 19:23, ARW wrote:
On 28/02/2019 18:57, GB wrote: On 28/02/2019 18:36, ARW wrote: On 28/02/2019 18:12, GB wrote: On 28/02/2019 18:02, ARW wrote: Of course the 18th edition has altered that for future installs (I think you are correct about the OPs lights) Is that on the basis that it's okay to get electrocuted by the lighting circuit? Perhaps it's a more refined way to die. Lighting circuits have generally been classed as safe without RCD protection. For some reason domestic lighting circuits they are now unsafe without RCD protection. The RCD, when it first came into general use was for outside sockets and using the lawnmower etc. Remember the RCD 13A plug in breakers before RCDs were common place in CUs? Our CU was replaced in 1998, and no RCDs for us. We have a couple of those RCD adapters. I have no idea whether they work, though, as they've never tripped. The CU looks like one of these: https://www.screwfix.com/p/crabtree-...mer-unit/5823p But it must be the 1998 version. There are 11 ways in use. Do you think I can fit a couple of RCDs in? If the Starbreaker has the plug in MCBs it may be possible to fit a couple of RCBOs. I was fitting RCD CUs well before 1998. A photo of your actual CU will help me decide if you can fit an RCBO (height restrictions apply). It looks low to me, but I'll check. You're saying that probably the simplest way to do this is to swap all the MCBs for RCBOs, provided they fit in the box? They are about £20 each though. As for your plug in RCD breakers. They should have a test button. This is nothing more than a switch to imbalance the load via a resistor. It will not tell you if the RCD is tripping within the required times but it will give you a guide as to it's ability to work. Yes, I occasionally test them. I recently had to throw one out because DW (at least I hope it was her, not me) had half-plugged an electric fire into one. The heat generated destroyed the plug and adapter. |
How Can This Happen (Electrical)?
On 28/02/2019 20:05, GB wrote:
On 28/02/2019 19:23, ARW wrote: On 28/02/2019 18:57, GB wrote: On 28/02/2019 18:36, ARW wrote: On 28/02/2019 18:12, GB wrote: On 28/02/2019 18:02, ARW wrote: Of course the 18th edition has altered that for future installs (I think you are correct about the OPs lights) Is that on the basis that it's okay to get electrocuted by the lighting circuit? Perhaps it's a more refined way to die. Lighting circuits have generally been classed as safe without RCD protection. For some reason domestic lighting circuits they are now unsafe without RCD protection. The RCD, when it first came into general use was for outside sockets and using the lawnmower etc. Remember the RCD 13A plug in breakers before RCDs were common place in CUs? Our CU was replaced in 1998, and no RCDs for us. We have a couple of those RCD adapters. I have no idea whether they work, though, as they've never tripped. The CU looks like one of these: https://www.screwfix.com/p/crabtree-...mer-unit/5823p But it must be the 1998 version. There are 11 ways in use. Do you think I can fit a couple of RCDs in? If the Starbreaker has the plug in MCBs it may be possible to fit a couple of RCBOs. I was fitting RCD CUs well before 1998. A photo of your actual CU will help me decide if you can fit an RCBO (height restrictions apply). It looks low to me, but I'll check. OK. So trying my best. If your CU looks like this https://www.tlc-direct.co.uk/Products/CBSBI00218.html Then RCBOs will probably fit. -- Adam |
How Can This Happen (Electrical)?
On Thursday, 28 February 2019 18:43:15 UTC, Robin wrote:
On 28/02/2019 18:12, GB wrote: On 28/02/2019 18:02, ARW wrote: On 28/02/2019 16:44, Robin wrote: On 28/02/2019 15:00, GB wrote: On 28/02/2019 14:38, dennis@home wrote: On 28/02/2019 14:15, Paul Herber wrote: On Thu, 28 Feb 2019 12:21:12 +0000, bert wrote: In one bedroom we have a ceiling fan supplied from the lighting circuit. It's been there for over 10 years no problems. In the past few nights a couple of times when switching it off the RCD protecting the ring mains has tripped. But the lighting circuits don't go through it and the lights are still on including the one which is part of the fan and the fan itself can be switched back on. Puzzled as to how this can happen - and where to start looking. Earthed via a the ring-main circuit? Probably not, RCDs don't just detect earth leakage but any current imbalance between live and neutral. It wouldn't actually matter where it was earthed if there was leakage to earth and it wouldn't affect other circuit unless they also had an earth leakage problem as RCDs aren't connect to earth. Quite agree. I think Clive is probably right as to the cause. Within the consumer unit, all the lives and all the neutrals are connected together, so there's scope for some coupling between circuits. The only thing that's really surprising (to me) is that the RCD protecting the lighting circuit does not trip. I wouldn't assume there there is an RCD protecting the lighting circuit. Â*Â*Very many homes don't have them. Of course the 18th edition has altered that for future installs (I think you are correct about the OPs lights) Is that on the basis that it's okay to get electrocuted by the lighting circuit? Perhaps it's a more refined way to die. It used to be on the basis of cost-effectiveness: the number of death and serious injuries from lighting circuits was much less than from a grand total of 1 sockets, showers, cookers etc. 20 or so per year I have no idea if the cost-effectiveness has changed with cheaper RCDs (bearing in mind there are also now safer light fittings and less need to change bulbs) as those who decided such things don't see fit to publish their assessments of costs and benefits of changes - if they even bother to make them rather than going with what they just know makes sense. it doesn't save any lives from shock. Whether it prevents any fires I can't say. NT |
How Can This Happen (Electrical)?
On 28/02/2019 18:02, ARW wrote:
8 Just for info and not related to the OPs question. Domestic properties are now required to have RCD protection on the lighting circuits even if the cables are run in a manner or of the type that would not require RCD protection (eg in trunking or SWA) Does that apply to circuits that only have fixed none user accessible stuff? It sounds like a half baked attempt to stop people putting their fingers in a socket getting killed. |
How Can This Happen (Electrical)?
In article , Tim+
writes bert Wrote in message: In one bedroom we have a ceiling fan supplied from the lighting circuit. It's been there for over 10 years no problems.In the past few nights a couple of times when switching it off the RCD protecting the ring mains has tripped. But the lighting circuits don't go through it and the lights are still on including the one which is part of the fan and the fan itself can be switched back on.Puzzled as to how this can happen - and where to start looking.-- bert It would suggest that it's not supplied by the lighting circuit... Tim But its definitely not supplied by any circuit protected by the RCD. -- bert |
How Can This Happen (Electrical)?
In article , Clive Arthur
writes On 28/02/2019 12:21, bert wrote: In one bedroom we have a ceiling fan supplied from the lighting circuit. It's been there for over 10 years no problems. In the past few nights a couple of times when switching it off the RCD protecting the ring mains has tripped. But the lighting circuits don't go through it and the lights are still on including the one which is part of the fan and the fan itself can be switched back on. Puzzled as to how this can happen - and where to start looking. Possibly a suppressor in the motor has failed and the resulting inductive spike is coupling into an adjacent circuit. Makes sense as you say it doesn't always happen, probably only when the voltage happens to be on a high part of the AC cycle. Cheers Now that is a possibility. Would explain why it has just started to happen. -- bert |
How Can This Happen (Electrical)?
In article
, Paul Herber writes On Thu, 28 Feb 2019 12:21:12 +0000, bert wrote: In one bedroom we have a ceiling fan supplied from the lighting circuit. It's been there for over 10 years no problems. In the past few nights a couple of times when switching it off the RCD protecting the ring mains has tripped. But the lighting circuits don't go through it and the lights are still on including the one which is part of the fan and the fan itself can be switched back on. Puzzled as to how this can happen - and where to start looking. Earthed via a the ring-main circuit? Are you suggesting that the qualified certified to whatever professional electrician who did this has screwed up? Well actually his dozy apprentice did most of the actual work 'til he fired him so yes quite possible. -- bert |
How Can This Happen (Electrical)?
In article , GB
writes On 28/02/2019 14:38, dennis@home wrote: On 28/02/2019 14:15, Paul Herber wrote: On Thu, 28 Feb 2019 12:21:12 +0000, bert wrote: In one bedroom we have a ceiling fan supplied from the lighting circuit. It's been there for over 10 years no problems. In the past few nights a couple of times when switching it off the RCD protecting the ring mains has tripped. But the lighting circuits don't go through it and the lights are still on including the one which is part of the fan and the fan itself can be switched back on. Puzzled as to how this can happen - and where to start looking. Earthed via a the ring-main circuit? Probably not, RCDs don't just detect earth leakage but any current imbalance between live and neutral. It wouldn't actually matter where it was earthed if there was leakage to earth and it wouldn't affect other circuit unless they also had an earth leakage problem as RCDs aren't connect to earth. Quite agree. I think Clive is probably right as to the cause. Within the consumer unit, all the lives and all the neutrals are connected together, so there's scope for some coupling between circuits. The only thing that's really surprising (to me) is that the RCD protecting the lighting circuit does not trip. There's no rcd on the lighting circuits. (I may be making a fool of myself here. Hope not!) -- bert |
How Can This Happen (Electrical)?
In article , ARW
writes On 28/02/2019 16:44, Robin wrote: On 28/02/2019 15:00, GB wrote: On 28/02/2019 14:38, dennis@home wrote: On 28/02/2019 14:15, Paul Herber wrote: On Thu, 28 Feb 2019 12:21:12 +0000, bert wrote: In one bedroom we have a ceiling fan supplied from the lighting circuit. It's been there for over 10 years no problems. In the past few nights a couple of times when switching it off the RCD protecting the ring mains has tripped. But the lighting circuits don't go through it and the lights are still on including the one which is part of the fan and the fan itself can be switched back on. Puzzled as to how this can happen - and where to start looking. Earthed via a the ring-main circuit? Probably not, RCDs don't just detect earth leakage but any current imbalance between live and neutral. It wouldn't actually matter where it was earthed if there was leakage to earth and it wouldn't affect other circuit unless they also had an earth leakage problem as RCDs aren't connect to earth. Quite agree. I think Clive is probably right as to the cause. Within the consumer unit, all the lives and all the neutrals are connected together, so there's scope for some coupling between circuits. The only thing that's really surprising (to me) is that the RCD protecting the lighting circuit does not trip. I wouldn't assume there there is an RCD protecting the lighting circuit. *Very many homes don't have them. Of course the 18th edition has altered that for future installs (I think you are correct about the OPs lights) He is. No rcd on lighting circuits. Personally I think they are as much a liability as a help. Just for info and not related to the OPs question. Domestic properties are now required to have RCD protection on the lighting circuits even if the cables are run in a manner or of the type that would not require RCD protection (eg in trunking or SWA) -- Adam -- bert |
How Can This Happen (Electrical)?
In article , GB
writes On 28/02/2019 18:02, ARW wrote: On 28/02/2019 16:44, Robin wrote: On 28/02/2019 15:00, GB wrote: On 28/02/2019 14:38, dennis@home wrote: On 28/02/2019 14:15, Paul Herber wrote: On Thu, 28 Feb 2019 12:21:12 +0000, bert wrote: In one bedroom we have a ceiling fan supplied from the lighting circuit. It's been there for over 10 years no problems. In the past few nights a couple of times when switching it off the RCD protecting the ring mains has tripped. But the lighting circuits don't go through it and the lights are still on including the one which is part of the fan and the fan itself can be switched back on. Puzzled as to how this can happen - and where to start looking. Earthed via a the ring-main circuit? Probably not, RCDs don't just detect earth leakage but any current imbalance between live and neutral. It wouldn't actually matter where it was earthed if there was leakage to earth and it wouldn't affect other circuit unless they also had an earth leakage problem as RCDs aren't connect to earth. Quite agree. I think Clive is probably right as to the cause. Within the consumer unit, all the lives and all the neutrals are connected together, so there's scope for some coupling between circuits. The only thing that's really surprising (to me) is that the RCD protecting the lighting circuit does not trip. I wouldn't assume there there is an RCD protecting the lighting circuit. **Very many homes don't have them. Of course the 18th edition has altered that for future installs (I think you are correct about the OPs lights) Is that on the basis that it's okay to get electrocuted by the lighting circuit? Perhaps it's a more refined way to die. Very limited opportunities to be electrocuted by a lighting circuit compared to a ring main. Just for info and not related to the OPs question. Domestic properties are now required to have RCD protection on the lighting circuits even if the cables are run in a manner or of the type that would not require RCD protection (eg in trunking or SWA) -- Adam -- bert |
How Can This Happen (Electrical)?
In article , ARW
writes On 28/02/2019 18:12, GB wrote: On 28/02/2019 18:02, ARW wrote: Of course the 18th edition has altered that for future installs (I think you are correct about the OPs lights) Is that on the basis that it's okay to get electrocuted by the lighting circuit? Perhaps it's a more refined way to die. Lighting circuits have generally been classed as safe without RCD protection. For some reason domestic lighting circuits they are now unsafe without RCD protection. The RCD, when it first came into general use was for outside sockets and using the lawnmower etc. Remember the RCD 13A plug in breakers before RCDs were common place in CUs? Still have one and recently put it into use. Had the lamp holder fail on a metal table lamp. Managed eventually to get a new skirt for it which was also metal. But the lamp was supplied with 2 core cable. -- bert |
How Can This Happen (Electrical)?
One on the fan unit and one at the wall. I've checked the wall switch
and tightened up the neutral connection by a turn or two. I've "instructed" (AKA pleaded with) swmbo to only use that switch for the time being. For reason best known to himself the electrician wired the extension circuits live to the switches whereas the rest of the house is wired live to the ceiling rose. In article , Brian Gaff writes Where is the switch for the fan, in the fan/light itself? I'd start there. Brian -- bert |
How Can This Happen (Electrical)?
On 28/02/2019 18:27, Brian Gaff wrote:
I was thinking of back EMF. That could make it back through the lights to the other circuits as a spike of some kind. Brian |
How Can This Happen (Electrical)?
On 01/03/2019 10:17, dennis@home wrote:
On 28/02/2019 18:02, ARW wrote: 8 Just for info and not related to the OPs question. Domestic properties are now required to have RCD protection on the lighting circuits even if the cables are run in a manner or of the type that would not require RCD protection (eg in trunking or SWA) Does that apply to circuits that only have fixed none user accessible stuff? It sounds like a half baked attempt to stop people putting their fingers in a socket getting killed. It does apply to the fixed stuff. However it's not actually a big game changer in the scheme of things. The 17th edition more or less made RCD protection compulsory for most new/altered domestic circuits so in 99% of cases this should not be a bigger issue than following the 17th edition regs. -- Adam |
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