Replacing this fuse box:

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Hello chaps, the other day, I posted the following onto IET Forums and lets be honest, the effort went to waste as only some were actually interested in helping, others were too fussed about who is going to do the work, how they will do it, the qualifications they will have to hold, why I am butting in...and all sorts. I then pointed out that I never did want to carry out the works myself, and instead want to apply whatever is gained from the responses to my studies. Its like the thought of me telling them I am pursuing a career in electrics, offends them!! Terrible I must say.
Anyhow, I mentioned that I would be posting onto this forum as the peepz on here are far more understanding than their lot!! Never again will I use that forum I tell u, (this is my personal opinion, some may disagree)
All I am after is a step by step guide to changing an ordinary domestic fuse box to a CU. I am not that competent to carry out the work myself as am aware there are several tests etc involved, before and after installation, I will be using the knowledge acquired to aid with me with studies, plus showing off to the spark I call in once I know the nature of the works involved!! :LOL:

It is a 3 bedroom house for which I am the landlord. A tenant asked me whether the electrics in the house were up to scratch, I wasn't too sure until I checked the fuse box and surrounding area. I opened up all socket outlets and found no issues whatsoever, all wire sizes seem to be correct throughout the house. No fancy showers, no electric cookers, no outdoor lighting, no additional spurs even. Just a heavy load on the downstairs ring, i.e. washing machine, dishwasher, microwave, kettle etc. (Like an individual once said, a typical grannys house :LOL: JohnD is the culprit) The 2 issues I came across were no equipotential bonding at all throughout the house, and the grannified fuse box!

I have posted these pics previously:
DSC00003.jpg


Protection with a 100A fuse:
DSC00004.jpg


Into the meter:
DSC00005.jpg


and into the fusebox:
DSC00007.jpg


How would a qualified spark go about rectifying the above. I know RF mentioned a replacement CU last time with 2 x 32A RCBO's, but would this be a straight swap. If the original fusebox had a max total demand value of 60A, could this be replaced with a 100A CU without having to upsize the cables going from the meter into the fusebox???
(original post : //www.diynot.com/forums/viewtopic.php?t=87043&postdays=0&postorder=asc&start=0)
And what sort of tests do you guys perform prior to and after works? Ze, Zs?? Do you have special equipment to obtain these results?
 
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dynomo said:
How would a qualified spark go about rectifying the above. I know RF mentioned a replacement CU last time with 2 x 32A RCBO's, but would this be a straight swap. If the original fusebox had a max total demand value of 60A, could this be replaced with a 100A CU without having to upsize the cables going from the meter into the fusebox???

And what sort of tests do you guys perform prior to and after works? Ze, Zs?? Do you have special equipment to obtain these results?

Whether the CU change is a straight swop depends on whether the installation meets the required standards. Before the CU can be changed the installation must be brought up to standard and any faults/deviations from the regs must be remedied before the replacement can commence.

If the tails are suitable for the main fuse and the expected load there is no need for them to be changed.

Some of the tests required:

verify continuity of protective conductors / bonding conductors / ring final conductors
Insulation resistance readings for all circuits
Earth fault loop impedance + electrode resistance if applicable
RCD tests

To perform all these tests requires either a number of separate devices (IR tester, RCD tester, low resistance ohm meter, EFLI tester) or a single multi-function tester which can perform all the tests required.
 
thanks for the speedy, this is the diff between this forum and that!!

I rmbr, upon purchase of this property 2 yrs ago, I had a periodic inspection carried out and the results wern't too drastic. Once Ive found the docs, I shall post them for you to see.
 
It would be worthwhile asking the electricity supplier if a new service head with PME can be provided. Say that the old one is cast iron and appears to be missing a fixing bolt on the RHS, and the Neutral connector looks insecure.

You will want to provide new 25mm tails and an earthing block with a length of 16mm G&Y for then to connect to if they agree to provide PME. The main bonds and earthing arrangements in that property are doubtless inadequate and a block will be very convenient. Get an 8-way.

When you are consulting an electrician see if he has a contact to get that done. Ask if he recommends provision of a 100A DP Switch in the tails at the same time.
 
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JohnD said:
It would be worthwhile asking the electricity supplier if a new service head with PME can be provided. Say that the old one is cast iron and appears to be missing a fixing bolt on the RHS, and the Neutral connector looks insecure.

Cheers John,
I shall contact EDF as soon as I get a chance. Can anybody provide a decent picture of the required service head with PME so I can examine and actually know what I am talking about when I get on the phone to them :LOL:

What if they refuse to replace, is this a case of living with what I have?
 
They probably will not refuse, but wether they charge you or not is another question.


PME head:


(Ignore the switchfuse back in the right of the picture)


IMGP20772.jpg
 
edited - I now see what you mean :oops:

(the point of the PME head is that it has an earth wire coming out of it, as well as the P and N)
 
Cheers RF,
now that looks pretty...
I notice the use of hardboard as a backplate, can we if we wanted to, use mdf or say pine or does the timber have to be fireproof etc? The status of my wall is....well you can see for yourself, very very poor.
 
Modern CUs have flame resistant enclosed backs (some are metal) so you haven't got to use a backboard. However they are quite convenient, and make it easy to fix things. You can space it off the wall and bring cables through the back, which avoids visible holes. If the wall surface is uneven or has crumbly mortar it may not give a good fixing surface.

A very good material for a backboard is laminated chipboard/MDF, as used for kitchen worktops and better quality cabinets. The Melamine surface will not support a flame, is non-conducting, and very easy to wipe clean. It also takes stick-on labels well and is easy to screw into (with pilot holes).
 
You want to be an Apprentice Armchair Bungler?
 
What did you think I was? :D

If I take you on, you'll eventually be a Master Bungler, like me :LOL: and sit around all day
 

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