Main Fuse


There is no isolator switch between the main inlet and the fuse board. I need to turn the power off to rewire a ring. I understand one has to pull the main fuse out of the inlet. How does one do this without zapping yourself.?
TIA
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload

Your fuse box or Consumer Unit should have a Main Switch. You should be able to rewire a ring to your fuse box by turning the main switch on the fuse box to OFF. You only need to pull the main fuse out to change the fuse box.
Adam
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload

There is other work so I still want to pull the fuse.If any one can advise?
TIA
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
Capt T wrote:

The only fuse before the consumer unit is the distribution company fuse - which will be held into its carrier with tamperproof seals, the same as the meter.
Provided that you are very, very careful - the main switch in the "fuse box", plus using insulated tools, should give you all the protection you need from being "zapped".
However, should you decide to break the seals, provided the mains switch(es) are all off and the meter isn't showing that power is being consumed, then removing the main fuse shouldn't be any more "exciting" than pulling a mains plug from a wall socket. There will be no current flowing through it and the voltage is "only" 240v.
The "exciting" bit happens later - if you have made even a very simple wiring error and plug the fuse back in with a fault in place. That can get *very* exciting, with a great risk of flash, fire, shock, death, house burnt down, etc.
If you don't know how to thoroughly test a ring main to ensure that it is safe, then you really shouldn't be going anywhere near the main fuse. I cannot over-emphasise how dangerous it is to plug it in, with a house wiring fault present. A *huge* current can flow, vapourising the copper contacts on the fuse holder instantly and sending it out as a conductive plasma at a temperature of over a thousand degrees. Your hand is likely to be at the centre of that...
--
Sue









Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload

Surely not. When you plug the fuse back in, the wire in it will blow - that is what the fuse is for after all. Anyway, the main switch in the consumer unit will be OFF at this point.
I hear stories of electricity board meter readers getting funny about the broken seal but I have never heard of anybody getting done for it. Electricians fitting consumer units routinely break the seal.
I have fitted some consumer units LIVE but I would not recommend it. The safest way to do it is to screw a 2 pole junction box near the meter output, and transfer the meter output leads to that, very very carefully. It needs insulated wire cutters (and preferably gloves) to cut the tails while they are live. Cut one wire and terminate it in the junction box, then cut the other one and terminate it in the junction box. After you have terminated both meter tails in the junction box, you can play around as you wish with the consumer unit - it's all dead.
Then you have a final exciting bit which is to connect the tails coming out of the new consumer unit to the junction box. Again, insulated tools and gloves.
The above is strictly for those who really know what they are doing with electrics. Done correctly, it's perfectly safe.
Nowadays, unfortunately, a DIY consumer unit installation is probably illegal and breaking the seal is going to draw attention to it having been done. This creates an incentive to do the installation live, using the junction box method. And using WHITE cable of course - you can still buy the stuff in certain trade outlets ;)
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
On Sat, 08 Mar 2008 08:38:13 +0000, nobody wrote:

==================================What's the significance of WHITE cable? I don't think I've ever seen white meter tails or white cable suitable for such purpose.
Cic.
--
===================================
Using Ubuntu Linux
  Click to see the full signature.
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
snipped-for-privacy@nowhere.com wrote:

There is nothing to stop the individual attempting to plug the fuse back in, with the mains switch on. A simple "mistake". Especially if the "ON/OFF" plate by the main switch hasn't been replaced..
However, there is nothing to stop an individual temporarily disconnecing the incomers in the consumer unit, to make things easier. Then wiring that up incorrectly.
The fuse *will* blow - once it has had a large enough current flowing through it for long enough. However, pushing a fuse carrier in by hand is a relatively slow process. It will pass through a phase with a significant amount of resistance between contacts. Which, in fault conditions, can generate a great deal of heat and light.. and that energy released in a small space will vapourise a lot of copper..

That would be the least of the OP's worries - if he attempted to push the main fuse back in with a dead short in the consumer unit..

So why mention it as a possibility? It is not something to even mention to an untrained DIY'er.
<snip description of something only trained and experienced people should attempt>

Agreed. But, anyone that has to ask how to do it doesn't meet that requirement. So why mention it?
--
Sue

Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
Palindrome wrote:

Just a bit of playing devil's advocate here but surely if you're going to attempt to replace said fuse all you'd have to do is check the voltage between the two ends of the fuse carrier before attempting to replace. If you've been an idiot and directly connected live and neutral/earth somewhere in the house it'll show mains voltage.
Just my 2p :)
Peter.
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
Peter Spikings wrote: <snip>

You miss the point. If the person knows enough to make safety tests - then there is no problem.
However, someone who has to ask almost certainly doesn't know enough.
DIY house wiring in general is potentially dangerous enough - but, for most mistakes the protection devices will do their job and limit the effects. The DIY'er stands a good chance of learning from the mistake.
However, mess with the main fuse......
--
Sue


Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
Palindrome wrote:

Ah, fair enough :)

Indeed.... I've done various things with electrics and have got by without much experience but with a good understanding of basic circuits and the differences between earth, neutral and live.... plus a bit of caution, a dollop of common sense and a healthy respect for the results of getting it wrong :)
While we're on this subject, does anyone know of a good web page that describes the Part P rules? I've tried looking for that before but failed to come away with many concrete facts from the point of view of a DIY'er.
Thanks,
Peter.
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload

http://www.elecsa.org.uk/downloads/TableofNotifiableWork.pdf
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload

Interesting table. Why don't they also prohibit wearing black underpants - it would be as enforceable. Can't even wire up a garden shed, under these regs.
My earlier comment about using white cable (still available trade) is that if you do the job in that, it looks like it pre-dates the regs and isn't going to get picked up on a check.
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
wrote

I assume you mean white T&E? Available everywhere, as is grey T&E and both were available pre and post part P. It was the inner cores that changed colours from red and black to brown and blue.
Adam
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
On Mon, 10 Mar 2008 22:52:51 +0000, ARWadworth wrote:

=================================If the wiring is the WHITE he means then it has no particular significance. My wiring has a mixture of white and grey although it's predominantly grey, and it all pre-dates Part P. I got the impression he meant white tails.
Cic.
--
===================================
Using Ubuntu Linux
  Click to see the full signature.
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload

Actually, sticking a test lead probe (of the type most people will have at home) into a main fuse carrier is a really bad idea. A slip, or the meter on the wrong setting, and you could easily be engulfed in an arc flash which would be extremely disfiguring, if not eventually fatal.
--
Andrew Gabriel
[email address is not usable -- followup in the newsgroup]
  Click to see the full signature.
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
wrote

Not very likely I agree. But I saw the mess someone tampering with a meter made of his hand. He also could not see for 3 days.

If the OP wants to remove the fuse (assuming there is only one) then you turn the main switch at the CU off, cut the seals on the fuse and pull it out. Good practice would then mean you check the supply is dead as vary rarely the fuse may be on the neutral side.
Adamv
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
On Fri, 07 Mar 2008 21:07:28 +0000, Capt T wrote:

=================================Buy an isolating switch (try http://www.tlc-direct.co.uk /) and get your supplier to connect new meter tails to it. You can then fit your own tails from the new isolating switch to the consumer unit. Subsequent work will only need the isolator to be switched off.
Cic.
--
===================================
Using Ubuntu Linux
  Click to see the full signature.
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
Hi As has already been posted you should have no need to remove the Main fuse however instalations vary and incomming cables are of many types .To remove a main fuse can take quite a tug ,sometimes this can loosen the whole board and in the worst case fracture the incomming cable.(this has happened I have a colege who has the burn scars to prove it). As for the quote 'it's only 240v' be warned 240v IS LETHAL .It is not the voltage that will kill you it's the current (amps) IIR 6-8 milli amps to stop the heart. Finally I think it is still a criminal offence to tamper with electricity company equipment and the main fuse and meter come into this category that is why they are sealed. Yes I know most people ignore this fact but if you have an accident trying to remove the main fuse you are to blame. My advice is to ring your supplier and ask them to fit new tails to a seperat 100a DP switch as already posted.
HTH CJ
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
writes

That is not correct

Neither is that

That is however fair comment.
--
fred
Plusnet - I hope you like vanilla
  Click to see the full signature.
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload

Site Timeline

Related Threads

    HomeOwnersHub.com is a website for homeowners and building and maintenance pros. It is not affiliated with any of the manufacturers or service providers discussed here. All logos and trade names are the property of their respective owners.