Hi. guys the main fuse coming into my house is 60amp .I am having an extention built and also want electrics in the garage. adding up the amps and taking in diversety ( Read up a bit) 60amps will not be enough. will the electric company be able to just replace the fuse with a 100amp, or will they have to run a new cable to my house.. the house is about 25 years old. Also if its just a matter of changing the fuse will my elecrtician have the autheroty to change it because there is a seel on the fuse. I do not want to get in trouble if he does not follow the rules. thanks
Main incoming fuse to small?
- Thread starter sparksparkbang
- Start date
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Your DNO might be able to just change the fuse, but this depends on the size and length of the supply cable. A point to remember is that a 60A main fuse will take well over 60A for a good few minutes before blowing. Also just because it says 60A on the cover that doesn't mean there is a 60A fuse installed. If the supply cable is not sufficiently sized then they will charge you to upgrade it.
An electrician does not have the authority to change the main fuse. Everything before your consumer unit is DNO territory. You can either contact your DNO directly if you know who they are or you can go through your electricity supplier. They should be able to tell you the actual fuse rating you have installed and they might be able to tell you if you can have it upgraded without the supply cable being replaced.
Davy
P.S I read on this forum that the DNO's work on a 10A per household basis because its rare that there is a continuous high power draw. I mean while you are cooking/showering you use lots more but just while watching TV with some lights on its unlikely you are going to be drawing more than about 10A continuously.
An electrician does not have the authority to change the main fuse. Everything before your consumer unit is DNO territory. You can either contact your DNO directly if you know who they are or you can go through your electricity supplier. They should be able to tell you the actual fuse rating you have installed and they might be able to tell you if you can have it upgraded without the supply cable being replaced.
Davy
P.S I read on this forum that the DNO's work on a 10A per household basis because its rare that there is a continuous high power draw. I mean while you are cooking/showering you use lots more but just while watching TV with some lights on its unlikely you are going to be drawing more than about 10A continuously.
What circuits do you have at the moment? What do you propose to add in the extension, any electric cookers or showers?
Possibly
Unlikely
No, its the DNO's fuse and their job, they'll have to check the network is adequate, electricians however do quite often cut the seal and remove fuses, they shouldn't, but sometimes its the only reasonably way to switch the power of for a CU change (calling DNO out to do that adds complications with times, etc), they shouldn't really, but its the real word and generally most DNO turn a blind eye to it as long as the meter seals are still there
but while you can get fuses and an electrician might be tempted to replace a blown one if need be, it'd only be a very shoddy electrician who took it up a size when he can't verify the network, etc
There is a 4 way consumer unit
Lights 5 amp
Ring 30 amp
Cooker 30amp
radial( emerson heater)15 amp (not used)
An add on shower unit with a 40amp fuse.
Add on requirements.
Obviously a new consumer unit.
I want a separate ring for the kitchen Because of all the appliances Washer, Dryer, dishwasher,Fridge, kettle, Microwave, Telly and probably more lol.
Another shower in the on-suite,
A new ring or radials for two new bedrooms
Power for garage, lighting and sockets ( nothing big powered from garage only 13amp DIY stuff)
The changes will just make a small single story bungalow into a normal sized 3 bedroom bungalow, with 2 showers and a garage supply.
Lights 5 amp
Ring 30 amp
Cooker 30amp
radial( emerson heater)15 amp (not used)
An add on shower unit with a 40amp fuse.
Add on requirements.
Obviously a new consumer unit.
I want a separate ring for the kitchen Because of all the appliances Washer, Dryer, dishwasher,Fridge, kettle, Microwave, Telly and probably more lol.
Another shower in the on-suite,
A new ring or radials for two new bedrooms
Power for garage, lighting and sockets ( nothing big powered from garage only 13amp DIY stuff)
The changes will just make a small single story bungalow into a normal sized 3 bedroom bungalow, with 2 showers and a garage supply.
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Consider a shower coming of the hotwater system, its unlikely your water feed will be enough to get a decent flow on each and you'd be pushing the max demand on a 100A supply a bit even (though I have no doubt that the fuse would hold, but you'd be bending the rules a bit)
If you have the time to spare just load your installation up to over 60A, blow the main fuse and call the DNO emergency number.
They will probably upgrade the fuse when they replace it
They will probably upgrade the fuse when they replace it
RF Lighting said:
Easier said than done, you'll have to pull 100A or so for half an hour
, or 120A for a bit over a minute (the curve is pretty steep at that point)http://www.bussmann.co.uk/images/Data Sheets/BS1361/LR85.pdf
Similar things with the 100A fuses, 150A will sit quite happily for quite a while, 200A will blow it but'll hang there for a minute or so
So in practice a household is unlikely to blow a 60A fuse, let alone a 100A one, you might pull high levels of current, but not for two long, natural diversity sees to that (unless you are doing your green fingers business in the attic!) as shower will be running 10-15mins, kettle takes 5 mins to boil, even if you are cooking... the cooker is cycling on and off, etc
I've heard of guest houses having stupid numbers of electric showers and not popping a 100A fuse
Crafty said:What a complete waste of energy. I found a 100A cutout fuse at work in the electrical room once, the OP can have it if he sends me an SAE.RF Lighting said:
What would be the point?
http://www.tlc-direct.co.uk/Products/MM100LR.html
I think some of you guys have missed my point I want a proper job!
Just a point. Even if I were to overload the circuits as surggested! Would the fuses in the CU not blow before the main one, lets say for instance, I was to plug an appliance pulling 13 amps into each socket there being 10 sockets on the ring that would be 130a from a 30a fuse, surly that would blow first being the weaker link?
I think it should be done right first time.
Just a point. Even if I were to overload the circuits as surggested! Would the fuses in the CU not blow before the main one, lets say for instance, I was to plug an appliance pulling 13 amps into each socket there being 10 sockets on the ring that would be 130a from a 30a fuse, surly that would blow first being the weaker link?
I think it should be done right first time.
In an ideal world the protective device closest to the fault/overload should operate first. It can depend on what else is connected too. If you have a shower drawing 45A, cooker 30A, then add a few ring circuits drawing large loads then the service fuse can operate. Diversity is applied to the design as it is unlikely that people will be using an installation in this way.
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