Change a old garage fuse board / Earthing question... pic s attached

[srl-8]

Hey,

I am looking to change a very old fuse box in my garage. I have attached pics for you all.
I am on route to becomeing a Domestic installer, and hoped i could get some more good advice if poss.

This old fuse box, is supplied from the main house Cu. It is on a 32A breaker. The Main Cu is protected by RCD.

The supply enters the garage from below ground in what looks like armoured cable. (see pic). I would like to change this to a small modern 3 or 4 way Cu, obiously with RCD. I will run a new radial & lighting circuit from the new Cu.

Question, I cannot identify a incomming earth ? All I can see is the Live and Neutral from the end of the Armoured Cable. Is this normal? The old metal box is earthed to a old copper pipe.. but cannot see a route back to the house main earth block?

What are my options here? Am I right to assume I either run a 10mm earth all the way from the garage back to the house Cu, Or install a earthing rod more local to the garage supply ?

I am still learning, so all advice or sugestions very welcome.

ps: Providing I am not running any large or abnormal loads from the garage, this supply from the house (on a 32a MCB) is suitable. I would only ever be plugging in the odd power tool, or running 2 light bulbs.. etc

Thanks!!


:stooge_curly:

 

[Deleted member 26818]

It looks like the live and neutral are about 2.5mm coming through the amor cable. what did you mean by..

"use the gas bond (if the SWA conductors are 10mm²), " ?

Sorry should be < 10mm².

 

[GLENNSPARK]

Parrallel earth paths should give you a lower Zdb n all depending on the main earthing of course.....

 

[diditrain]

As the others have suggested, a good read up on exporting and discrimination is required and maybe use a micrometer to determine the csa of your armoured cable

 

[william7900]

Hi,

I just wrote a thread concerning this problem. The earth from the house should never be run to the garage. Lets assume that during digging you accidently went through the SWA cable. You would receive a severe shock because you are actually in contact with the earth and providing a lovely path to earth. The garage should always be earthed using the TT arrangement consisting of earth rods. So 2 wires from house to garage is correct, with the earth supplied from earth rods. Building sites use equipment supplied by sepearted supplies ( a transformer) where no earth is used for safety. Hope this helps.

Regards,

Bill

 

[Deleted member 26818]

The armour of SWA is designed, so that if the cable is penetrated by a metallic object, the armour will provide the earth path.
Why would someone connect the armour to an unreliable high resistance earthing point such as an earth rod, as opposed to a reliable low resistance earthing point such as would be supplied with a TN system.
As for the reference to building site supplies, is the supply to the shed, separated?

 

[stansmith]

when i read threads created by domestic installers who havent got a clue about what theyre saying it makes me want to retrain to be something else, what a bummer that the system is allowing these courses be accepted and these cowboys let loose when REAL sparks sit a 4-5 apprenticeship it does my head in! well id like to see them try and get on a building site anyway whoops gutted because your not sparks haha

 

[srl-8]

Stansmith, firstly what a stupid responce you have just posted. A domestic installer, (when fully trained/assesed and certified by one of the approved bodies, eicnic, elecsa, napit etc) is more than capable of carring out electrical work within their scope.

If i knew 'everything' i wouldn't be on here asking questions. I am learning, and at no point do i consider myself to compete with fully trained and time served sparks. However, we all (even you at somepoint) has to start somewhere.


Most persons on this site have been extreamly helpfull, and I have learn alot from them. I guess I wont be learning anything useful from you.

Lastly, If i wanted to get a job on a building site, it would be quite easy. I would approach the contractor as an electricans mate, to gain experience and only when I was fully confindent, I would then take on greater responsibilities.

Anyway, sorry that you think people like me are cowboys, nor we dont have a clue. I have to disagree with your opinions.

All the best

S

when i read threads created by domestic installers who havent got a clue about what theyre saying it makes me want to retrain to be something else, what a bummer that the system is allowing these courses be accepted and these cowboys let loose when REAL sparks sit a 4-5 apprenticeship it does my head in! well id like to see them try and get on a building site anyway whoops gutted because your not sparks haha

 

[Deleted member 26818]

Srl-8 the line through stansmith's name indicates that he has been banned.
It was decided that he was notreally the kind of person we want as a member of the forum.
He may if he want's read your post, but he won't be able to respond.

 

[malcolmsanford]

S8 while sometimes the "time served" guy can get a little vocal over this I think what E54 wrote about the Domestic installer, was not the guys themselves but the training centres is spot on and I have to agree.

Unfortunately in today's world the old tried and trusted method of training in now a rarity due to costs etc and sometimes the only way into the industry is through perhaps not perfect training. what is a concern to most "time served guys" is that the DI is actually still learning the basics and making what could be very very serious mistakes due to inexperience.

The time served guy was lucky that even nearing the end of an apprenticeship he would still be under the wing of an experienced electrician, and mistakes that were made were picked up and learnt from, unfortunately the DI does not have this luxury and that is the bottom line really.

 

[srl-8]

I agree with your comments malcolm, it is a concern for me aswell, but this is the route that the government have deemed to be acceptable. I personally think the short course does not prepare you anywhere near enough, but it does give you the building blocks to continue.


With the power of the internet, books, and forums like these, there isnt much you cant find out.

I would love to have a experience sparks look over my shoulder for 5 years, but that is just not available to me, or lots of other budding electricans.

We can only but try are best, and fingers crossed.. We reach own goal.