Any domestic electricians inna house?

Funkster · Post by **Funkster** » Tue Sep 21, 2004 6:23 pm

'lo all,

Are any of you lot household electricians? I want to make some changes to my consumer unit (swap out the master RCD so that I free up some space for more circuits - current RCD is 4 blocks wide, I want to replace it with a 2 block wide one of the same spec) and obviously I need to isolate the supply to the RCD before doing this.

So, how do I go about turning off the supply to the consumer unit? There's wire tags on all the stuff before that and stickers saying "electrical contractor only" and so on. Am I allowed to cut the tags (and where can I get replacements if so?) or is this illegal?

Cheers for any hints/help/advice!
--
Olly

marksmith · Post by **marksmith** » Wed Sep 22, 2004 9:09 am

Hello,

I had to resort to getting an electrician in to do something similar to this. The RCD box (as you probably know) is "safe" - you can pull the cover off and wire in new circuits without being exposed to any of the live bits. (Clever design meaning you need to remove the RCDs to get to the terminals, and of course they're not live with the RCDs removed.)

But to remove the RCD box altogether there's no way of switching off the power without pulling apart the meter (metal tags etc.) or something else you don't own/don't want to touch.

I didn't see what the electricians did - but I suspect they pulled apart the meter and disconnected something inside that. You can't do it yourself, anyway.

Good luck! Don't kill yourself.
-Mark

talkingcars · Post by **talkingcars** » Wed Sep 22, 2004 10:01 am

I replaced my whole consumer fuse box, well installed one as all teh house had were 2 single "fuse wire" boxes

but

THAT IS REALLY DANGEROUS!

as you have loose live cables.

If you need to install more circuits why not add a second unit and if need be get a quilified spark to to the live connection.

James

steve-o · Post by **steve-o** » Wed Sep 22, 2004 11:40 am

I'm an electrician. Not sure exactly what you want to do, sounds like you're trying to modify your existing unit, which is a "no no". But if you're intention is to replace the entire consumer unit with a more up to date and larger unit with more "ways", it is quite a simple preocedure.

To isolate the supply at the source (ie: before it reaches the consumer unit) you need to find where your electricity meter is, usually in a locked up cupboard outside the house or on older houses near to the consumer unit itself. Here you should find that the 2 mains cables (the live and neutral) come out of the ground and go into the meter, the live will go via a 100Amp fuse. The 100Amp fuse will have a metal tag on it (to stop you pulling it out) if it hasnt already been tampered with. You need to remove this fuse to isolate all the power to your house (hence you'll have to snip off the metal tag), everything past the point of this fuse will be isolated and you can go about removing your unit safely.

A few points to note are, you really shouldnt be doing this. The law states that anyone tampering with the wiring in the household is responsible for that wiring. That means should anything go wrong or someone gets hurt or even dies, you would be liable.

Also, you are not qualified and that also means you are taking big risks and breaking certain laws. Regulations state once a job like this has been done, each and every circuit should be tested for safety before you continue to use it. (Hence the liability thing again)

If you decide to go ahead and do this job regardless, you need to aquire a test meter. It is important that even once the mains fuse has been removed, you check the voltage has infact been disconnected by double checking with the appropriate equipment in the appropriate places.

Also, make sure you know exactly where each circuit came from and that you are sure on how to wire it back up again, taking note of breaker ampage ratings etc.

I would suggest you dont carry out this work yourself as in my opinion there are 2 things you should never mess with if you dont know about them, and thats electricity and gas. Get a proper spark in to do the job right and be safe in the knowledge something disasterous wont happen in the future, such as your house burning down or someone hurting themselves becasue of your doing!

Just me 2p's worth.

Steve.

Funkster · Post by **Funkster** » Wed Sep 22, 2004 12:15 pm

Wotcha, cheers for the advice. I don't want to modify the consumer unit as it has enough ways, but 4 of those ways are currently taken up by the RCD. More modern RCDs seem to all be 2 ways wide, and I want to free up those 2 ways to install more MCBs.

I think though that I'll put the circuit in and get the wire up to the CU and then get a spark round to change the RCD and put the new breaker in.

I do know what I'm doing, but you're quite right - I'm not officially qualified. I keep meaning to do the exams and so on as it would be really useful. A friend of mine at my last job did it and I don't think it was too expensive / time consuming to do.

Thanks again,
--
Olly

steve-o · Post by **steve-o** » Wed Sep 22, 2004 1:14 pm

Ahhh, I see.

Well if all you're doing is swapping an RCD (I presume its for a power shower or something?) from an old sized one to a newer one, which you're right, all tend to occupy 2 ways. Yeah, rip it out, swap it, free up 2 ways, no problems!!!

Run in your new circuits, bang in 2 new MCBs for them and wire up piece of cake!

Got wrong end of the stick as usual! You can do all this yourself easy peasy!

Funkster · Post by **Funkster** » Wed Sep 22, 2004 2:01 pm

steve-o wrote:Got wrong end of the stick as usual! You can do all this yourself easy peasy!

But how do I change the RCD without turning off the power to it? I was assuming that I would need to unscrew the feed wires going to/from it. Is this incorrect? If it's just 'plugged in' and I don't need to touch the live wires then that's great.

Thanks,
--
Olly

Enak · Post by **Enak** » Wed Sep 22, 2004 2:23 pm

The main breaker is a tricky one... Really, you need you local utility company (e.g. EDF) to disconnect the consumer unit. Although, if you are stupid you could disconnect the breaker with a live supply.

Furthermore, you need to check how the ins are wired to the main breaker. They may have terminals that only accept the four wide breaker.

The safest, easiest (and probably cheepest option if you want to play by the law) is to get an additional consumer unit and piggy back that from your existing unit. For example, remove lighting breakers into the new unit to free up some slots.

Always use wiring rated greater than the breakers.

Changing things inside the consumer box is something that should be undertaken by a qualified electrician.

Funkster · Post by **Funkster** » Wed Sep 22, 2004 3:29 pm

Enak wrote:The safest, easiest (and probably cheepest option if you want to play by the law) is to get an additional consumer unit and piggy back that from your existing unit. For example, remove lighting breakers into the new unit to free up some slots.

That sounds like the way to go. I can have one small CU next to my current one for just lights, then use the other new free space in the current CU to feed my new circuit.

The reason for all this is to put power into my loft - I want to move my server up there and want proper power available. I'll probably put another CU in the loft for separate lights and sockets circuits.

Cheers for the help,
--
Olly

steve-o · Post by **steve-o** » Wed Sep 22, 2004 3:57 pm

Right, hang on a sec.

Are you saying the breaker you want to change is the main 60Amp breaker that disconnects power to the rest of the consumer unit? Or are you saying the RCD you want to change is simply occupying 4 ways on your load side?

When you said RCD, you tend to only have them on things that require RCD's like power showers or outdoor power.

Regardless, easiest choice is to add a small consumer unit next to your existing one with a feed tapped off the main breaker. BEst option is to change the complete unit for a larger one with more ways (looks nicer!)

If you ever need to disconnect the main supply before the consumer unit, like I said before, all you need to do is pull the 100Amp fuse that will be situated close to your electricity meter. This should remove all power, but you should double check it with a test meter.

Anyway, now you've said you want to get power into your loft, you dont need extra ways anyway, simply pick up a feed from your ring main which will run in the loft anyway, tap into it and add all the sockets you need for the loft, same goes for the lights, a light circuit will already run through the loft, pick up the feed and add the necessary light circuits to the existing circuit. You have no need to add extra MCBs. You wouldnt do any harm by tapping into the existing circuits and adding whatever you need.

Steve.

Enak · Post by **Enak** » Wed Sep 22, 2004 4:00 pm

The fuses have the metal tag's on them cause you're not suppose to tamper with them... You could end up with a fine if you break them.

Funkster · Post by **Funkster** » Wed Sep 22, 2004 5:59 pm

steve-o wrote:Right, hang on a sec.

Are you saying the breaker you want to change is the main 60Amp breaker that disconnects power to the rest of the consumer unit? Or are you saying the RCD you want to change is simply occupying 4 ways on your load side?

When you said RCD, you tend to only have them on things that require RCD's like power showers or outdoor power.

I think I've been mixing terminology up a bit. When I said RCD, I meant incomers (that's right isn't it? the switch that supplies power to all the MCBs in the CU). Mine has a 100mA RCD in it rather than just being a switch, so I thought that RCD was the right term. Seems you can also get RCDs to run individual circuits, which is what you thought I meant earlier?

I did scout around for a circuit in the loft, but only found lighting stuff... is it possible that all my socket wires are in the floor between upstairs and downstairs?

'tis a late '40s/early '50s semi if that makes any difference.

Thanks for the advice, I'm pretty sure I can sort it out now, with no need to start playing with the wire tags or any dodgy stuff.

:oD
--
Olly

steve-o · Post by **steve-o** » Wed Sep 22, 2004 8:26 pm

Yeah it is possible that all your ring mains are under the upstairs floor boards and only your light circuits are in the loft. But I'd have a good look just to check you havent missed anything. Sometimes you'll get the odd socket wiring making its way to the loft, especially if someones done any mods to the wiring before you got your mitts on it!!!

So we have the lights sorted, you can just take the permanent feed from the light circuit and make your own circuits onto this.

Your alternatives for the sockets are (providing you can't find any 2.5mm twin in the loft) dig up a couple of floor boards (runs along the landing are always a good bet for finding good places to tap into the ring main without disturbing too much funiture) and throw a circuit into the loft. Problem with this is it can get a bit messy if you have solid internal walls and need to chase out cable runs.

However with the age of your house access to the cables should be easy as you "should" have floor boards and not the crappy chip wood squares used in later homes!!! (they really are a pain in the back side!) But saying that, if you were going to add completely new circuits anyway, you would have had to make alot of mess getting the cable runs from the consumer unit to the loft anyway, so I guess the mess or work doesnt bother you!!!

I now understand your RCD explaination, but you shouldnt have to gain access to the live side of the consumer unit now and should be able to get feeds from somewhere else.

(As for cutting the metal tag on the fuse, it is there for your protection and for anyone else, but when needs must, they get cut, but who's to say you cut it and not someone else! If it bothers you, a trip to the local leccy shop will sort you with a new tag.)

It is perfectly safe to add whatever circuits you want to an existing one, (providing the ring is kept in tact and you dont wire "radially") you dont need to uprate any MCB's and should never put MCB's in greater than the current carrying load of the wire. MCB ratings are another kettle of fish that I won't bore you with!!!

Steve.