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Changing a RCD

Community Veteran
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Registered: 02-08-2007

Changing a RCD

I Need to change a RCD in the fuse box but cannot see where the electricity can be turned off for the entire house.
The old external electric mains fuse box had a handle which could be put in the off position but since then we have had a new digital meter fitted, just below the meter there is a large mains fuse but clearly this is not meant to be access as it has a wire and seal through it.
Anyone any ideas about this ?
The individual RCDs are screwed in but the face of the internal fusebox has to be removed first thus exposing the live rails the fuse clips to.
27 REPLIES
Community Veteran
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Re: Changing a RCD

Your consumer unit ('fuse box') should have a switch marked 'main switch', this isolates everything from the incoming feed.
If in any doubt, employ a qualified electrician.
Call me 'w23'
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nanotm
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Re: Changing a RCD

some of the older consumer units don't have it marked (there was a space for the sparky to put the sticker on but the lazy ones never bothered) but its a different all red lever normally on the end and not part of the busbar for the various loops
if your unit is like this one :
http://fastfixservices.co.uk/electrical/fuse-box-upgrades/ (about half way down the page)
then the double red isolator switch is what your looking for
if its one of the grey metal box type units and your not running a commercial premises then you should be getting it changed, but there should also be a double ganged lever at one end,
or better yet throw the lever (switch) at the meter point as that will definitely isolate the entire cct
just because your paranoid doesn't mean they aren't out to get you
Community Veteran
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Registered: 02-08-2007

Re: Changing a RCD

Similar to that one in the picture, will have a go at changing it this Sunday.
If you get no further posts from me then take it things did not go well.  Smiley
nanotm
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Re: Changing a RCD

if you have any doubt open the meter cupboard and there "should" be a lever or switch in there you can "throw" in order to isolate your entire building
personally I would use it as there is nothing so bad as getting a belt off what you believed to be isolated mains .......
also use one of those tester screwdrivers before you start playing with the wires, if there still live after using the mains isolator at the meter point you need to speak to the electrikery board as someone connected the building in the wrong fashion ......
just because your paranoid doesn't mean they aren't out to get you
pwatson
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Re: Changing a RCD

Are you really sure you know what you're doing?
Is it an RCD or MCB you're changing?  Why does it need changing?  How will you check that the live busbar is not powered?  

nanotm
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Re: Changing a RCD

Quote from: pwatson
 How will you check that the live busbar is not powered?  

unless he's playing with DC wouldn't it be more prudent to make sure that both sides of the supply are isolated before playing with it ?
as to why you would change an RCD, I did it a few months ago when one we had refused to stay open, although in fairness I just swapped it with one of the other same rated modules that was listed as spare
just because your paranoid doesn't mean they aren't out to get you
Community Veteran
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Re: Changing a RCD

Hope so, will be finding out on Sunday.
As suggested I will check the busbar with a tester screwdriver before proceeding.
Why do I need to change it, well the fuse is 16Amp and I believe it should be 32Amp. Why do I think this, well I have checked a neighbours fuse box and for the Garage supply it a 32 Amp RCD.
The reason I wish to change it is that it keeps tripping ONLY when I use a power washer with a motor rating of 2400 Watts, how do I know it's not a faulty power washer well if I plug it in to the house sockets which has a fuse rating of 32 Amps then it works ok so I assume the motor is drawing an initial high current to start and that's what is triggering the RCD.
How do I know the supply to my garage can take 32 Amps well there is an armoured cable that's fairly thick leading to the garage with a rating of over 70 Amps so that combined with what my neighbour has (same type and age of house built by the same builders) I think I should be ok in changing the RCD.
 
pwatson
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Re: Changing a RCD

For your own safety, I really would advise that you get an electrician...  Nothing that you've written inspires any confidence that you know enough about what you're doing Sad

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Re: Changing a RCD

How do you know if the wiring will take more than 16 amps?
Geoff,
York.
nanotm
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Re: Changing a RCD

find out what grade it is and look it up, most mains wiring has a code printed on it at intervals, failing that you could get a wire gauge and measure the cross sectional area, perform some tests with a mega and compare the results with those in the regulations (but its rather a complicated process for the novice)
in general I would advise getting a professional in to do the job, or at the very least get someone who's qualified, other than DIY gas fittings there's nothing more dangerous in the average home than bad electrics....
just because your paranoid doesn't mean they aren't out to get you
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Re: Changing a RCD

Use my Serbian electrician called Nick Tesia
Now Zen, but a +Net residue.
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Re: Changing a RCD

Quote from: nanotm
unless he's playing with DC wouldn't it be more prudent to make sure that both sides of the supply are isolated before playing with it ?

Neutral is usually at the same potential as ground (give or take a volt or two). The live swings positive and negative around it. Testing with a neon tester is usually a wise move though.
pwatson
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Re: Changing a RCD

Testing with a neon tester is never a good idea (and in this case unnecessary)
I suggest given that the OP

  • Doesn't know how to isolate the supply

  • Hasn't correctly named the item that he thinks needs replacing

  • Hasn't proposed the correct solution to the problem

  • Thinks that because his neighbour's installation looks the same it's OK

  • etc


the wisest course of action is to strongly suggest that the work isn't carried out.  I certainly don't feel comfortable in offering advice on how to do the job properly as it will encourage the OP to have a go and potentially leave an unsafe installation (or worse!)
I'm all for anyone doing something themselves (I'm not an electrician btw) and I realise that it's a 'chicken and egg' situation to get the necessary initial knowledge.  Advice from an Internet forum isn't the best way though  Wink 

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Re: Changing a RCD

I've never paid for electric, gas or water work in my house, preferring to do it all myself.
Although not qualified, I do have a good working knowledge of each service and where there are gaps in the aforesaid knowledge I will read up.
However I have to agree with pwatson that if you feel the need to ask for advice in this forum you would be better off seeking the assistance of a qualified electrician.
There may be a very sound reason for the RCD being rated at 16 amps, most notably the rating of the cable attached to it.
PS I have a neon screwdriver but my best friend is my digital multimeter.
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