Discuss Hello, can you help me with my ring main / fuse board? in the Electrical Forum area at ElectriciansForums.net

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xenon20

Hi to all

My plug sockets upstairs are supposed to be on a ring main, I have continuity from the fuse board to all seven sockets but the final leg back to the fuse board has no continuity on the live wire. It's possible that it has been like this for years and that the circuit has always been running as a radial circuit. I have now replaced the 30A rewirable fuse with 15A fuse wire.

To run a new wire will be very difficult given the route the current wire is taking, is it safe to leave the circuit as a radial with a 15A fuse fitted?

Also I was interested in swapping some/all of the rewirable fuses with mcb's but have no idea whether I can get them for my fuse board (I can't find the part number of it). It tells me that it's an "MEM Memera" but thats all it says. Its a black box which takes fuse holders that have 4 prongs that are of vertical orientation. I cant find any pictures of it on google images. I am guessing it was installed when the house was built around 1981.

Any help is greatly appreciated.

Thanks

Xenon
 

telectrix

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Hi to all

My plug sockets upstairs are supposed to be on a ring main, I have continuity from the fuse board to all seven sockets but the final leg back to the fuse board has no continuity on the live wire. It's possible that it has been like this for years and that the circuit has always been running as a radial circuit. I have now replaced the 30A rewirable fuse with 15A fuse wire. better to fix it properly. either repair the L, or spkit the N and E

To run a new wire will be very difficult given the route the current wire is taking, is it safe to leave the circuit as a radial with a 15A fuse fitted?

Also I was interested in swapping some/all of the rewirable fuses with mcb's but have no idea whether I can get them for my fuse board (I can't find the part number of it). It tells me that it's an "MEM Memera" but thats all it says. Its a black box which takes fuse holders that have 4 prongs that are of vertical orientation. I cant find any pictures of it on google images. I am guessing it was installed when the house was built around 1981. cost as much to buy breakers as it will to buy a new CU

Any help is greatly appreciated.

Thanks

Xenon
my comments in red
 
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xenon20

Thats a quick answer to the fuse board question, thanks! perhaps I will look into getting a new CU at some stage.
 

telectrix

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as for the sockets. i would go to the last 1 and disconnect the leg that's got the open circuit L. obviously diss. it at the CU as well. then you'll have a 15A radial circuit, and as long as you don't want any heavy loads it will be fine.
 

sparks1973

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if the C/U you have (fusebox) is good for continued service...that is to say that the enclosure is in good order (IP rating), the CORRECT fusewire is fitted (disconnection times) and any labeling/notices are present (identification of circuits)..then whats up with it?....you may want additional protection by means of RCD...there again it may be a TT system wheras any RCD fitted then will be for fault protection....still doesn`t mean you have to condemn the C/U though....just fit a stand alone 30mA RCD....
Theres too much of this just `condemning` stuff without really looking at it....
and as for the ring that isn`t....isolate at the C/U and prove dead, fuse in pocket (safe isolation)....remove fronts one by one on this circuit till you find the offender...you say its supposed to be a ring....so i doubt the problem will be in a joint box under the floor.....but you never know until you look so go for the easily accessable stuff first .....
 
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xenon20

as long as you don't want any heavy loads it will be fine.
All my computer and music equipment (13 plugs), fan, two lamps, alarm clocks, bedside lamps, printer, occasional hairdryer, occasional fan heater in winter.

This be classed as heavy?
 

Top Cat

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All my computer and music equipment (13 plugs), fan, two lamps, alarm clocks, bedside lamps, printer, occasional hairdryer, occasional fan heater in winter.

This be classed as heavy?
Only the fan heater, 1 Kw = 4 Amps, 2 Kw = 8 Amps, 3 Kw = 12 Amps, aprox.
 
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xenon20

if the C/U you have (fusebox) is good for continued service...that is to say that the enclosure is in good order (IP rating), the CORRECT fusewire is fitted (disconnection times) and any labeling/notices are present (identification of circuits)..then whats up with it?....you may want additional protection by means of RCD...there again it may be a TT system wheras any RCD fitted then will be for fault protection....still doesn`t mean you have to condemn the C/U though....just fit a stand alone 30mA RCD....
Theres too much of this just `condemning` stuff without really looking at it....
and as for the ring that isn`t....isolate at the C/U and prove dead, fuse in pocket (safe isolation)....remove fronts one by one on this circuit till you find the offender...you say its supposed to be a ring....so i doubt the problem will be in a joint box under the floor.....but you never know until you look so go for the easily accessable stuff first .....
There's nothing particularly wrong with the board, its just that I wanted a higher level of protection for peace of mind really. I'm a novice so RCD/MCB is a bit confusing! Do you know if its possible to get an RCD for my type of fuse board?
 

sparks1973

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There's nothing particularly wrong with the board, its just that I wanted a higher level of protection for peace of mind really. I'm a novice so RCD/MCB is a bit confusing! Do you know if its possible to get an RCD for my type of fuse board?
well you have 2 choices here....theres the fit a new C/U...an option already pointed out .....or you can put a stand alone RCD next to the existing C/U....its a cheaper option for you....but the downside of this arrangement is of course that if the RCD lets go for any reason....you have lost supply to the WHOLE install....so no lighting....this could be a potential danger in itself..(think stairs).....so its upto you....i mean...what are the earthing arrangements here for a start?.
 
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xenon20

To be honest if I were to do anything to the current setup I would just update the whole lot to a modern c/u with rcd/mcbs. I will consider this in the near future once we know if we are staying in this property.

Many thanks for all your help!!

Xenon
 

mickys86

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Reading
There's nothing particularly wrong with the board, its just that I wanted a higher level of protection for peace of mind really. I'm a novice so RCD/MCB is a bit confusing! Do you know if its possible to get an RCD for my type of fuse board?
This is frightening. The only advice should be save up the £400 (more than likely to be less) and have a PROFESSIONAL come and install it


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StuSpiers

Make sure you get a sparks in to do that as it is most definitely not a DIY job, and furthermore would require building control notification.
 

sparks1973

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To be honest if I were to do anything to the current setup I would just update the whole lot to a modern c/u with rcd/mcbs. I will consider this in the near future once we know if we are staying in this property.

Many thanks for all your help!!

Xenon
well i would do a `limited IR test` on this install whenever you get a mo`....a limited test is normally agreed with the person ordering the test..or any other interested parties first...so in this case yourself.....so, you test each live conductor to earth.....you will be looking for a minimum of 1 MEG...if testing each circuit individually....or 2 MEG...if testing globally (at the tails)......dont forget those strappers either....oh, and another thing as well.....you may have what we call a `shared neutral` here....there again you may not either....but to prove it you can IR test between each circuits neutral...and if any of em come back flat then thats what it will be ...this will pose probs for a split load C/U as the RCDs will keep letting go as they will sense imballance on the neutral side.....so theres quite a bit to consider before you procede....but an hour with the megger will tell you loads about the install as is....
 

Guitarist

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If you are a novice, then definitely get a qualified electrician in mate. Better to spend a bit of cash than end up a victim of an electrical accident.
 
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xenon20

If you are a novice, then definitely get a qualified electrician in mate. Better to spend a bit of cash than end up a victim of an electrical accident.
Oh yes, If I decide to go down that route then I will get the Pro in to install. Certainly not a DIY job, especially for somebody with as little experience as me.

Cheers
 
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