DIY Doctor

Fuse boxes

Postby LES EATON » Thu Jul 01, 2010 1:32 pm

I've been told that the old-fashioned fuse boxes are now illegal, and should have been replaced with the 'trip-switch' unit.

Is this true, and if so who is supposed to foot the bill.
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Postby ericmark » Fri Jul 02, 2010 2:45 pm

It is not Illegal however it may not comply with current regulations.
Depends what you mean by old fashioned!
The re-wire-able fuses in theory need to be changed by a skilled person and for all intense and purpose and out puss many have asbestosis in them so really are now not to be seen in any domestic premises.
However the cartridge fuses are still used and there is nothing wrong with them.
Some fuse boxes will allow one to change from re-wire-able to cartridge or MCB with very little expense but then we do get into the Legal thing. It may be covered under Part P. I say may and it is open to interpretation.
Also to change type in theory one should check the readings taken with some expensive meters to ensure they comply. However if they complied with the old likely they will with the new.
Again we enter a grey area and if one adds something new one should comply with latest regulations but to repair old it is not required so it could be said you can't alter the fuse box without completely upgrading.
As a result if you get an electrician to do the work some will do just the minimum required and others will claim much more needs to be done. Since they are signing paperwork it is their call and I can't say they would be wrong to want to change whole box as I say grey area.
As to whom well it is nothing to do with supplier of the electric and likely it will be the owner who has to fork out for the work.
All domestic are by the regulations to have their electrics checked every 10 years of change of occupant which ever is shorter but regulations are not law but they can be quoted in a court of law so not to follow them means if any one is injured then look out.
The law is quite odd as it does say one should not make a house uninhabitable and to turn off gas or electric would be considered as doing just that so although one can turn off dangerous circuits one can't just switch off without ensuring there is some other accommodation available.
So an Electrician doing an inspection can't turn your power off he can only advise if dangerous and in real terms I have never done an inspection where there was not some minor thing which did not comply. But when changing a fuse board he is likely to find other faults. To day all circuits must be RCD protected so a new board would include RCD's as well as MCB's the latter replaces the fuse. The RCD measures the power out and the power back and if all is well these should be the same. If they are not then it must be leaking to earth. Nothing is perfect so it is considered that up to 15ma can leak without tripping the device but over 30ma may cause the human body permanent harm so 30ma is the maximum allowed to leak.
These RCD's are more expensive than a simple switch so a new box according to size will cost £70 to £300 and it will take between 1/2 a day and whole day to fit. But as already said likely there will be more faults so likely 2 days wages for the electrician.
A good electrician will want to do an inspection (PIR) as part of the job mainly to identify any problems before he starts as to say after changing the box that your immersion heater will no longer work is not very helpful but he could fit first than just isolate any faulty bits. So better if he tests first then he can give you a price for doing all work required.
Cookers often are faulty and once the box is changed will no longer work so it is a good idea to get important items checked before he starts too.
Now this is where the who pays becomes a problem. If a rented house the landlord is often only responsible for the installation i.e. the main wiring and he is often not got to provide new fridge, freezer, washing machine, Drier, Dishwasher and cookers. All these may prove faulty and some like the washing machine are very hard to test so only show up after the change.
It is of course not he's fault or the electricians that you were unaware of the faults. A plug in RCD is cheap and testing each item in turn to see if they are OK by running them for 24 hours each is a good plan if you don't want any unexpected bills. May be you can borrow one?

So to recap not illegal as you are but not a good situation so first step would be to get a PIR done and a quote.

Since the replacement for a fuse box does not contain fuses the name has changed and the type tested distribution box used in a house is called a "Consumer Unit" since the power needs switching off to change you may need to have an isolator fitted first by the electric supply company but you electrician will advise.
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Postby jimmy_one_ball » Mon Jul 19, 2010 8:28 pm

No you don't have to replace them at all, in fact you can still install them in new houses according to appendix 12 of the regs, just so long as they are RCD protected and the circuits are split and configured correctly. External RCD's can be used.
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Postby kuzz » Mon Jul 19, 2010 8:49 pm

thought I'd jump on this thread as it's kind of relevant, rather than start a new one.
What do you electricians do who work for yourselves when a customer wants a fuse box changed to a 17th edition board, but don't want to upgrade to 10mm bonds?
To turn work down seems stupid, when no bonds 4mm bonds or 6mm bonds you would still make the installation safer with a modern consumer unit.
You can't force them to pay, so is it just a case of noting it on the perodic? is this ok with nic eic and other simalar organisations?
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Postby ericmark » Tue Jul 20, 2010 2:05 pm

I am sure in your heart of hearts you know the answer.

"Sorry I can't do that you will need to find a cowboy electrician."

It may seem your turning work down but if you upset your inspector and you lose your Part P status you will be turning a lot more work down.

New installations require an installation certificate not a periodic and you can't note faults as such you can only stipulate extent of work.

This can be a problem were one guy is fitting a kitchen, another is doing stair lift, another the bathroom and yet another changing the consumer unit. This has happened to me. Lucky all for a disabled person so did not need to be registered all done free of charge through LABC.

The same problem when you find a fault like suppliers earth is missing and you provide an earth block ready for the DNO to connect to but are not going to be there when the DNO does the work.

Of course one has to issue an installation certificate and all one can do is note no supply waiting for DNO on certificate. You can't issue a completion certificate as the work is not complete. Which in turn means you are not working through your scheme provider but must work through LABC which means an extra fee.

I suppose you could fit an earth rod and turn it into a TT which does not need a 10mm earth cable. However I did have a problem where a guy had a very good earth and it melted the earth cable going to his shed when the DNO lost their earth/neutral after some one working on road hit the cable.

As a result I personally would not argue it would just be a "No sorry".
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Postby sparx » Wed Jul 21, 2010 12:10 pm

Kuzz, et al,

Suggest you look at 'electrical safety council' website, (
go to section called 'business & community', click on guides, then download number 6.
it gives exactly what you are asking about and is agreed by niceic (old name for ESC), NAPIT and others,
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Postby jimmy_one_ball » Sat Jul 24, 2010 9:23 pm

[quote="jimmy_one_ball"]No you don't have to replace them at all, in fact you can still install them in new houses according to appendix 12 of the regs, just so long as they are RCD protected and the circuits are split and configured correctly. External RCD's can be used.[/quote]

I was wrong to say appendix 12 of the regs, I said that on someone elses word without checking for myself, what I should have said is "according to reg 432.4 Characteristics of protective devices where BS3036 is listed (which is a semi-enclosed re-wireable fuse)". :oops: My appologies for that Les but it is definately still Ok to have them, even installed in new builds so if anyone ever says that they are illegal to you quote that reg at them.

All The Best
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Postby audreygreenwood » Fri Oct 24, 2014 2:52 am

Well I don't claim to be an expert on electrical matters, but I'm sure there's a reason to use the more up-to-date fuse box than anything else? I'm sure a person can probably hold off getting it done for a while and save himself some moneey, but at the end of the day, if it's gotta go into a packing box to make way for a new one that performs better, than that's what just has to happen!
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Postby ericmark » Fri Oct 24, 2014 10:33 am

It is clearly a problem using fuse wire as to work out if the correct wire has been used is near impossible hence why now only allowed where there is a electrician always on site to change the fuse wire as people have used all sorts of wire in the past. To remove a fuse wire and measure it's thickness will likely take longer than replacing so any Electrical Installation Condition report would likely mean all fuses would need replacing to ensure correct size.

With cartridge fuses we do not have this problem. The marking on the fuse tells us what it is. However again it means often the fuse needs removing to read the size. The humble fuse can in certain circumstances rupture quicker than a MCB and we still use fuses to protect semi-conductors.

Even with a modern consumer unit you can get fuse holders instead of MCB's although once you go over 16A the diameter of the fuse means it will not fit in the 12.5 mm of a single module.

The main problem is the RCD where we need to maintain for example lighting when a socket circuit has a fault and the old consumer unit would in the main mean having one RCD for all circuits. But in my house with two old type consumer units each with it's own RCD it still complies with the regulations.

I would expect the original poster in two years will have decided what to do. The amendment 1 no longer permits auto re-setting RCD's for domestic use.

In the main the problem is when people want extra sockets. New sockets must comply with new rules and so unless surface cables and RCD sockets are used then the consumer unit needs changing.

With fuse v MCB often the fuse can be better. But any fuse must get hot in fact the wire inside melts so there is a minimum size for a cartridge fuse and it is more because of the fuse physical size than not being suitable why we no longer use fuses in a domestic consumer unit.
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