Hi All you DIY's
New to this, so hope I explain myself OK. We have armoured cable 2 core laid about 27 years ago running underground for 100ft from our house to our garage at the end of the garden.
Last weekend all the power went the garage, no lights and the one and only double socket on the wall was dead. First thought was the MCB on our Protues CU board had tripped, but it hadn’t. Then checked the two fuses in the garage on a separate fuse box, not blown either.
Called my stepson who is an electrician albeit he is still in his early days, but has better knowledge than me or my husband. We ask him what the test button on the RCD on the main CU in the house is for, he suggests pressing it to test if the RCD trips, we press it and nothing happens. So he then suggests turning off the main RCD manually then turn all the mcb’s off, switch RCD back on and then one by one turn each MCB back on. Well that was a great idea, except the main RCD wouldn’t go back on. Anyway I won’t bore you with any more info on that. We came to the conclusion that our 19 year old Protues board needed changing as we were unable to locate a replacement RCD due to its age.
Had an electrician come out last week (not stepson) as he lives in Wales (250 miles away) unfortunately, to fit a new CU. I bought a Moeller split load board and the electrician fitted it knowing we had this fault with the garage circuit. After fitting the new board the main RCD would trip out as soon as the mcb for the garage was turned on ( the mcb for the garage stayed on though). He did a few tests then left saying he didn’t have enough time to check it out any further, nor did he have a special tester to check for live power running straight through the cable from end to end. Plus we didn’t know where under the floor in house the junction box would be, as the cable size in the garage was different from the size terminating at the CU, so they must be a join in the cable somewhere.
I had a good idea where the join would be and the next day had the carpet and floor boards up. Sure enough there was an old metal JB with the armoured cable going in. Took the lid off and ran various tests, i.e., disconnected all the three wires of the armoured cable from the block connector in the JB, then turned the power back on. Main RCD didn’t trip, connected earth an neutral back up, didn’t trip, disconnected all 3 wires at garage end and then put the live wire back in at the house end and it tripped. Swapped live & neutral around in JB and it didn’t trip, so now we think that somehow the live cable inside the armour has suddenly started to short out to earth.
This cable was disturbed about 5 years when we landscaped the garden, but it was buried again under concrete and has been fine for those last 5 years. The thought that this cable might be faulty is giving me nightmares, there is absolutely no way we can ran another cable in its place. The garden is now concrete slabs and bricks walls and then the last 20ft it’s under a concrete car port we built. It would also be very hard to run another cable taking a different route underground, it would have to be above ground which I believe is OK. If we dig up the old cable which is possible for about 10ft , where the cable is running under grass, can we join a new piece of cable if we discover the fault is beyond the cut we make ?????.
Sorry this is so long just need to put you all in the picture.
Why would this fault just develop like that anyway, has anyone else known of armoured cable getting a live fault whilst undisturbed buried in the ground for years. The only other thing that keeps bugging me, but sure it’s just a coincidence , is that the night before it went out , we had an extension lead running out the garage running a radio, it started to rain so after 15 mins unplugged the radio and moved it else where. We left the extension lead out in the rain for a further 45 mins before putting it away in the garage. Next day plugged the extension lead in to a car charger then hours later noticed the car charger was off, discovered the 13a fuse in the plug of the extension lead had blown, changed the fuse,plugged car charger back in, it worked for 2 seconds then went off again. This is when I discovered the socket on the garage wall wasn’t working and you know the story from there.
So, can we double check the cable is US, if so can we ran another one above ground, or join the old one with new cable if we can find the bad bit to eliminate.
Hope you can help need electric up the garage 24/7. Car battery is now in my kitchen on charge all the time. Its off our car that doesn’t really go anywhere, sort of an old classic so the battery needs to be trickle charged all the time.
Thanks all lot for reading all this.
Julea
New to this, so hope I explain myself OK. We have armoured cable 2 core laid about 27 years ago running underground for 100ft from our house to our garage at the end of the garden.
Last weekend all the power went the garage, no lights and the one and only double socket on the wall was dead. First thought was the MCB on our Protues CU board had tripped, but it hadn’t. Then checked the two fuses in the garage on a separate fuse box, not blown either.
Called my stepson who is an electrician albeit he is still in his early days, but has better knowledge than me or my husband. We ask him what the test button on the RCD on the main CU in the house is for, he suggests pressing it to test if the RCD trips, we press it and nothing happens. So he then suggests turning off the main RCD manually then turn all the mcb’s off, switch RCD back on and then one by one turn each MCB back on. Well that was a great idea, except the main RCD wouldn’t go back on. Anyway I won’t bore you with any more info on that. We came to the conclusion that our 19 year old Protues board needed changing as we were unable to locate a replacement RCD due to its age.
Had an electrician come out last week (not stepson) as he lives in Wales (250 miles away) unfortunately, to fit a new CU. I bought a Moeller split load board and the electrician fitted it knowing we had this fault with the garage circuit. After fitting the new board the main RCD would trip out as soon as the mcb for the garage was turned on ( the mcb for the garage stayed on though). He did a few tests then left saying he didn’t have enough time to check it out any further, nor did he have a special tester to check for live power running straight through the cable from end to end. Plus we didn’t know where under the floor in house the junction box would be, as the cable size in the garage was different from the size terminating at the CU, so they must be a join in the cable somewhere.
I had a good idea where the join would be and the next day had the carpet and floor boards up. Sure enough there was an old metal JB with the armoured cable going in. Took the lid off and ran various tests, i.e., disconnected all the three wires of the armoured cable from the block connector in the JB, then turned the power back on. Main RCD didn’t trip, connected earth an neutral back up, didn’t trip, disconnected all 3 wires at garage end and then put the live wire back in at the house end and it tripped. Swapped live & neutral around in JB and it didn’t trip, so now we think that somehow the live cable inside the armour has suddenly started to short out to earth.
This cable was disturbed about 5 years when we landscaped the garden, but it was buried again under concrete and has been fine for those last 5 years. The thought that this cable might be faulty is giving me nightmares, there is absolutely no way we can ran another cable in its place. The garden is now concrete slabs and bricks walls and then the last 20ft it’s under a concrete car port we built. It would also be very hard to run another cable taking a different route underground, it would have to be above ground which I believe is OK. If we dig up the old cable which is possible for about 10ft , where the cable is running under grass, can we join a new piece of cable if we discover the fault is beyond the cut we make ?????.
Sorry this is so long just need to put you all in the picture.
Why would this fault just develop like that anyway, has anyone else known of armoured cable getting a live fault whilst undisturbed buried in the ground for years. The only other thing that keeps bugging me, but sure it’s just a coincidence , is that the night before it went out , we had an extension lead running out the garage running a radio, it started to rain so after 15 mins unplugged the radio and moved it else where. We left the extension lead out in the rain for a further 45 mins before putting it away in the garage. Next day plugged the extension lead in to a car charger then hours later noticed the car charger was off, discovered the 13a fuse in the plug of the extension lead had blown, changed the fuse,plugged car charger back in, it worked for 2 seconds then went off again. This is when I discovered the socket on the garage wall wasn’t working and you know the story from there.
So, can we double check the cable is US, if so can we ran another one above ground, or join the old one with new cable if we can find the bad bit to eliminate.
Hope you can help need electric up the garage 24/7. Car battery is now in my kitchen on charge all the time. Its off our car that doesn’t really go anywhere, sort of an old classic so the battery needs to be trickle charged all the time.
Thanks all lot for reading all this.
Julea