cabby Posted January 23, 2010 Report Share Posted January 23, 2010 Got up this morning to find the fuse on the 'socket circuit' of the main board had tripped so simply reset. The garage has power and this is fed from the house (13amp fused socket inside house) and this fuse had blown also. Inside the garage there is another fuseboard with a 15amp and 5 amp fuse. The garage fuseboard feeds 2 lights (one internal and one external) and a socket with built in RCD. The RCD socket is used to power a fridge freezer and a dusk-til-dawn light (4-way pug board fed from socket). I've replaced the 13amp garage fuse inside the house 3 times and each time this blows and trips the main board. The last time I did this everything worked for 20 mins before going again. Any ideas how I work out where the problem is? Link to comment Share on other sites More sharing options...
Calm Chris Posted January 23, 2010 Report Share Posted January 23, 2010 Water in the lamp outside ? Am I right in thinking that the setup is:- House ring circuit 30a -> f/spur 13a -> feeder cable to mini cu in garage-> 5a MCB feeding 2 x lights and 15a MCB feeding -> RCD socket with fridge on and a 4 way extension lead. A bit of a mash up . Check the lamp, but really that should have taken down the 5a MCB in the garage CU 1st ! I'd turn off the CU in the garage and re energise the main MCB in the house CU, then turn on the f/spur feeding the garage. Leave and hopefully no trip. I'd then re energise the CU in the garage (without the light MCB on) leave and see if anything trips. If it does it the socket circuit, extn socket or device plugged on it causing the problem. If everything ok, then the light would appear the likely suspect. Without being there and doing insulation resistance tests there's no 'guess' method to resolve the fault. With the poor weather I'd suspect the external light and any junction boxes that may have become damp. Link to comment Share on other sites More sharing options...
cabby Posted January 23, 2010 Author Report Share Posted January 23, 2010 Water in the lamp outside ?A bit of a mash up . Too right! The setup is as you've described. I really do need someone to give it a bit of an overhaul and put some more sockets in. I (think) i've been trying what you suggested i.e. a process of elimination. I've unplugged the 4 way lead with no change. The remaining external light (which has been off the whole time) appears to be dry. When I was in the garage I did notice that when the power inside the house (the 13 amp spur) was turned back on the board in the garage made a popping sound but that the fuses didn't blow which seems odd. :confused: Link to comment Share on other sites More sharing options...
Calm Chris Posted January 23, 2010 Report Share Posted January 23, 2010 I'd turn if off at the fuse spur and then take the lid off the garage CU- It could be a loose neutral (or anything loose). Sparking / arc noise should be none existant or at worse only for 5 ms or however long the switch takes to go off to on. Do check, there's no burning, no smoke, no discolouration or distortion. They can end up like these:- Link to comment Share on other sites More sharing options...
cabby Posted January 23, 2010 Author Report Share Posted January 23, 2010 Cheers Chris - will have a look tomorrow in the daylight. Link to comment Share on other sites More sharing options...
cabby Posted January 24, 2010 Author Report Share Posted January 24, 2010 Checked the garage CU and all looked fine. Turned on following the order above and, before I even turned the garage CU back on, the main fuse and the 13 amp spur had tripped. Is is possible there is something else in the house i.e. not something in the garage, that is causing the 13 spur and main CB to trip? Your confused Link to comment Share on other sites More sharing options...
Calm Chris Posted January 25, 2010 Report Share Posted January 25, 2010 You need to unplug everything on the circuit throughout the house. So if the 13a f/spur is a spur off the kitchen ring then unplug or turn off everything on the circuit. Then with the MCB on and the f/spur off do you still have an energized circuit ? If so then start turning on each appliance and device. If the MCB pops then hopefully you will have id'd the faulty equipment causing the trip. If the MCB pops without any device connected then there's a possibility that the MCB has failed, the other thing to consider is have you done any DIY recently that might have caused an issue. I'm thinking crushed cable, nail or screw hitting cable, damp socket, flood etc. If you are up to it, you could move the wiring from MCB to another similar rated MCB. If you do this, has the fault cleared or is it the same on the new MCB position ? Obviously if the fault doesn't move the MCB is suspect, if it does move it's got to be wiring or something hanging off the wiring. Link to comment Share on other sites More sharing options...
Cockney Boy Posted January 25, 2010 Report Share Posted January 25, 2010 (edited) One quick question, how far is the cable (13amp) from the house to the garage? The reason i ask, is the loading on the 13amp Fuse plus the length and size of the cable could be contributing to the probelm. If none of the applicances blow the fuse indipendantly, then it will be a loading issue. Imagine a garden hose, and you trying to push 30 gallons a second through the pipe, something will give!!!! Checked the garage CU and all looked fine. Turned on following the order above and, before I even turned the garage CU back on, the main fuse and the 13 amp spur had tripped. Is is possible there is something else in the house i.e. not something in the garage, that is causing the 13 spur and main CB to trip? Your confused Edited January 25, 2010 by Cockney Boy Link to comment Share on other sites More sharing options...
Calm Chris Posted January 25, 2010 Report Share Posted January 25, 2010 Cockney Boy, from what has been mentioned the circuit isn't new and has worked. So although your suggestion is valid, it's unlikely. The 13a f/spur puts a limit on the load beyond the spur (garage CU) of 13 amps. A 2.5mm TE feed can cope with about 26 amp, so it's unlikely to be the cable. If the MCB's in the CU (15 amp and 5 amp) were being used to full load I'd expect the f/spur to fail 1st since it can only handle 13 amp + 20% (for short periods). As a supply to the garage I have 'assumed' that the garage is attached to the property, or at worst 5/10 m away. Over small distances voly drop really shouldn't be an issue on a 2.5mm cable running at 13 amp f/spur load. Cabby is the f/spur is part of a kitchen ring or ground floor (non kitchen) ring ? Kitchen's tend to have more appliances that could fail, since things such as dish washer, washing machine, tumble drier, kettle all have issue on failure due to water use. Link to comment Share on other sites More sharing options...
cabby Posted January 25, 2010 Author Report Share Posted January 25, 2010 The garage is detached but only 2m from the house. The 13 amp spur is on a 'socket' circuit for the ground floor - things like lamps, phone, TV etc. I did change all downstairs sockets and switches when we decorated but that was a few months ago. Will try the first part of what you suggested Chris but will probably turn to a professionsal for the more complicated things you mention (me and electricity have had a few 'issues' in the past which I need to remind myself when I get a bit carried away). Is there a plug-like device that will allow me to test each socket to help identify this? Many thanks chaps. Chuffed with TSN's (Well Chris in particalar) helpfulees as usual!! Link to comment Share on other sites More sharing options...
Calm Chris Posted January 25, 2010 Report Share Posted January 25, 2010 The 13 amp spur is on a 'socket' circuit for the ground floor - things like lamps, phone, TV etc. And you have a seperate circuit for the kitchen ? It would be sensible to confirm exactly what is on the circuit in question. Number of single and double sockets, items plugged in to the circuit etc. Martindale make simple plug in testers which indicate LNE working and correct polarity. Only of use on sockets, it won't be any good for testing fused spurs. I'd suggest you follow my previous suggestions (such as removing all appliances / switching off all sockets) and see what happens. A pro visit with a IR tester / mega is likely to be the quickest option regarding resolving the problem. Link to comment Share on other sites More sharing options...
Cockney Boy Posted January 25, 2010 Report Share Posted January 25, 2010 Cable type/cross section and distance from the garage was never disclosed, so as you put it we had to "assume" this, now that we know its within 2M of the house we can move to other concultions. Cockney Boy, from what has been mentioned the circuit isn't new and has worked.So although your suggestion is valid, it's unlikely. The 13a f/spur puts a limit on the load beyond the spur (garage CU) of 13 amps. A 2.5mm TE feed can cope with about 26 amp, so it's unlikely to be the cable. If the MCB's in the CU (15 amp and 5 amp) were being used to full load I'd expect the f/spur to fail 1st since it can only handle 13 amp + 20% (for short periods). As a supply to the garage I have 'assumed' that the garage is attached to the property, or at worst 5/10 m away. Over small distances voly drop really shouldn't be an issue on a 2.5mm cable running at 13 amp f/spur load. Cabby is the f/spur is part of a kitchen ring or ground floor (non kitchen) ring ? Kitchen's tend to have more appliances that could fail, since things such as dish washer, washing machine, tumble drier, kettle all have issue on failure due to water use. Link to comment Share on other sites More sharing options...
cabby Posted January 27, 2010 Author Report Share Posted January 27, 2010 And you have a seperate circuit for the kitchen ?It would be sensible to confirm exactly what is on the circuit in question. Number of single and double sockets, items plugged in to the circuit etc. Martindale make simple plug in testers which indicate LNE working and correct polarity. Only of use on sockets, it won't be any good for testing fused spurs. I'd suggest you follow my previous suggestions (such as removing all appliances / switching off all sockets) and see what happens. A pro visit with a IR tester / mega is likely to be the quickest option regarding resolving the problem. OK, the kitchen is separate. The circuit in question feeds the remainder of the ground floor of the house. This includes 5 double sockets, 2 single sockets and 2 fused supplies (one for igniting the gas fire which is permanently off and the other for the garage). A typical loading would be 3 x lamps (all energy saving bulbs), 2 cordless phone bases, TV + digibox and ipod dock. I tried out your advice by switching of the fuse on the MCB and then unplugging everything on the circuit. I then put a new fuse in the fused supply to the garage and turned on the MCB fuse. I then turned on each item waiting for 30 seconds or so between them. Each came on and was fine. 10 mins or so after the last item was turned on everything went off. I reset the MCB fuse assuming the 13 amp fused supply had blown (it's impossible to tell visually when they have gone) and everything came back on - this time for perhaps 2 mins. I repeated this again and got even less time before everything went off again and the MCB tripped. It seems on this occasion the 13 amp fused supply didn't blow. I'm guessing this as I removed the fuse (some 40 minutes ago) then reset the MCB and all has been ok since. . I also bought a LNE socket tester today and everything tested fine. Link to comment Share on other sites More sharing options...
Calm Chris Posted January 28, 2010 Report Share Posted January 28, 2010 Cabby, so from what you have mentioned would it be safe to suggest that the ring circuit in the house works and it's ONLY when the garage supply feed is turned on via the f/spur that the problem of mcb trip and / or f/spur fuse blows ? If so, at least we are getting closer ! I'm still perplexed that the garage CU makes crackling noises and the fault appears to be beyond the 13a f/spur. I think it could be time to get a spark with a multi function tester over to mega / insulation resistance test the whole circuit and see what can be found via test. At the moment I'm leaning towards the garage CU being the fault point or the cable beyond the f/spur having broken down, become damaged (rodent, mechanical or age). Could you confirm that the mcb trip has occurred when the garage CU is 'off' and the f/spur on or does the trip only happen when the whole circuit part beyond the f/spur is on (ie f/spur on, garage cu on, mcb's on garage cu on, sockets and lights in garage on ? Link to comment Share on other sites More sharing options...
cabby Posted January 28, 2010 Author Report Share Posted January 28, 2010 Cabby, so from what you have mentioned would it be safe to suggest that the ring circuit in the house works and it's ONLY when the garage supply feed is turned on via the f/spur that the problem of mcb trip and / or f/spur fuse blows ? Yep. Could you confirm that the mcb trip has occurred when the garage CU is 'off' and the f/spur on or does the trip only happen when the whole circuit part beyond the f/spur is on (ie f/spur on, garage cu on, mcb's on garage cu on, sockets and lights in garage on ? It's happening with the garage CU off - it's been like that since the weekend as wasn't sure I should be leaving it on (I think it was happening when it on as well). Link to comment Share on other sites More sharing options...
fingermouse Posted January 29, 2010 Report Share Posted January 29, 2010 What sort of wire feeds the garage??? is it in conduit or amoured ??? Link to comment Share on other sites More sharing options...
Calm Chris Posted January 29, 2010 Report Share Posted January 29, 2010 What sort of wire feeds the garage??? is it in conduit or amoured ??? I was under the assumption that it was a simple 2.5mm TE cable:confused: Link to comment Share on other sites More sharing options...
cabby Posted January 30, 2010 Author Report Share Posted January 30, 2010 The cable runs under the patio (that bit worries more as this thread gets longer) and i'm pretty sure it was there from the house was built about 15 years ago. Looks like a decent job was done and the one small section of cable that can be seen is about 30mm in diameter and feels very solid so assuming it is armoured. Link to comment Share on other sites More sharing options...
cruiser647 Posted February 1, 2010 Report Share Posted February 1, 2010 Maybe some pictures of what you can see would help? Link to comment Share on other sites More sharing options...
Calm Chris Posted February 1, 2010 Report Share Posted February 1, 2010 The cable runs under the patio (that bit worries more as this thread gets longer) and i'm pretty sure it was there from the house was built about 15 years ago. Looks like a decent job was done and the one small section of cable that can be seen is about 30mm in diameter and feels very solid so assuming it is armoured. Pictures at the f/spur and garage CU with both covers off required Link to comment Share on other sites More sharing options...
cabby Posted February 2, 2010 Author Report Share Posted February 2, 2010 A pic. of the garage CU with a pic. of the spur to follow. I tugged each of the connections and everything appeared fine. If, as I suspect, the cable between the house and garage is a pretty decent sized armoured cable, what are the chances these has been damaged by rats? Link to comment Share on other sites More sharing options...
cabby Posted February 6, 2010 Author Report Share Posted February 6, 2010 A few of the spur and the armoured cable as it enters the garage. Link to comment Share on other sites More sharing options...
cabby Posted February 6, 2010 Author Report Share Posted February 6, 2010 Realised that there is a fused spur in the garage for the external light so turned this off on the basis that the more I can isolate the more I can eliminate. In effect the only device drawing any current from the garage CU now are two lights; one internal and one external. I went through the normal routine of replacing the 13amp fuse in the internal spur and went into garage and turned the light on. Fine for a minute then the garage CU made a 'pffft' sound indicating the 13amp spur had fused tripping the MCB. Turned CU in the garage to 'off' and reset the MCB and replaced the fuse. Ok for a minute or two then the 13amp fuse goes again tripping the MCB. This narrows the problem down to somewhere between the internal spur of the garage CU. Really hope it's not the cable as will be a PITA to replace given it runs under a patio . Any further suggestions welcomed but think it's about to time call someone in. Link to comment Share on other sites More sharing options...
mb Posted February 8, 2010 Report Share Posted February 8, 2010 Bypass the cable temporarily with some cable laid above ground & see if have the same issue ? Link to comment Share on other sites More sharing options...
cabby Posted February 8, 2010 Author Report Share Posted February 8, 2010 Bypass the cable temporarily with some cable laid above ground & see if have the same issue ? I like your thinking - good plan . Any ideas what the minimum spec. of cable spec. is that the I should use for this? Not really up on cable types/terminology. Link to comment Share on other sites More sharing options...
Recommended Posts
Please sign in to comment
You will be able to leave a comment after signing in
Sign In Now