Friendly advice needed please . . . .

[vickery1971]

Hello All, Please go easy on me as I am relatively new to the profession. I have my annual surveillance visit and plan to offer up a Distribution board (being done tomorrow) and a Garage rewire (left part done as assessor requested so I can do dead tests), They are both at the same property.
The house, a 60’s bungalow has old wire fuses, no RCD but has a pool and Jacuzzi bath! . . . . it may prove to be interesting!

I just wanted to say what I plan to do so I can get some opinions on the best way to do things . . . . Here goes!

First change the main CU for a 17[SUP]th[/SUP] dual RCD board with one non RCD’d way in which I will put a 40A MCB from which I will run 6mm 3 core SWA using spare core as CPC (25m clipped direct VD 5.84 with a load of 32A)
Metal Wylex garage CU with one 32A ring, 6A lighting, 16A radial to pool. (ring in garage as the assessor likes me testing his ring!)

My experience with sub boards on SWA is limited but I plan to gland and bond the SWA each end. Q1: When I test for my Zdb do I do it with the glands linked or just using the 6m earth in the SWA? Q2: If there happens to be a metal water pipe in the garage am I right that I have to run a 10mm earth from the main DB to DB2 (it’s tns) and bond the water?

Thanks for any advice you can give.

Ian

 

[shocking_eg]

didnt you ask a similar question before ?

may be usefull to do a couple of tests on existing installation before fitting an RCD board otherwise you could be letting yourself into a lot of headache especially if not that experienced with the testing side

 

[shocking_eg]

metal service pipes or extraneous building steels etc.. then will need a min of 10mm to house MET

 

[vickery1971]

Asked a question about a sub board in a flat a year ago, maybe thats it? . . . . reading other 'garage posts' it appears to get people angry for some reason.

Thanks for the advice, I plan to do the board change this week, cant really leave the poor people with a pool and jacuzzi and no RCD, on the plus side the attic is clear and it appears to be a 4mm ring with drops from JB's, ive had a poke about before i offered my services!

 

[shocking_eg]

Think people get a bit wound up is probably because the same sort of questions are asked and most answers can be found with a search

Be carefull with hot tubs in particular as they like to trip out RCDs when the heater elements are breaking down

A lot of customers don't like being told that their "working" equipment needs changing when they think nothing's wrong with it !

 

[vickery1971]

Cheers for the heads up, I know the family fairly well and have explained that i may unearth a few issues!

I have been reading posts all evening and it never ceases to amaze me how many different opinions people have and how people interpret the reg's, when you are a novice its a bit of an advice minefield! . . . . Thats why i just thought i would say what I was going to do (My interpretation of the rules) and see if i get ripped apart . . . . so far so good!

 

[HandySparks]

What's the earthing system? (I can't see it in your OP.)

Edit: Just re-read, TN-S.

 

[vickery1971]

Hi, its TNS

 

[Essexboy7]

whats Zdb?

 

[vickery1971]

Ze at DB2 (The garage CU)

 

[Essexboy7]

cheers ,never heard of it .There was a question exactly like that in the 2391 exam but i have never heard it called Zdb before thanks for the clarification

 

[onions1066]

Isn't zdb when you can't disconnect main earth to take a ze? Been a long time since 2391. If this is for your assessment you really need to be fitting a rod for the garage.

 

[vickery1971]

zdb . . . . zebedee . . . . .boing (Showing my age now)

I was tought it was the Ze taken at a board other than the main CU . . . . but as usual i could be very wrong!

And reading the posts on garage one person goes right off his handle at people TT'ing garages . . . . so im not going to even talk about it for rear of getting torn apart!

Thanks for the posts anyhow

 

[vickery1971]

But in answer to my OP, does what i plan to do sound ok? . . . . Its how ive done it before and how ive seen other people do it (40yr veterans of which my late father was one before i get slated for being a novice) . . . . but as im using it for my serviellance piece i just wanted to get a few opinions on different ways of doing it . . . . and im sure there are many

answers on a postcard

Boing said zbd . . . . .time for bed

 

[onions1066]

By rights you should really install a rod for the garage, you shouldn't really export the suppliers earth out of the equipotential zone without there written permission, people will moan regarding this but that's the deal. That could be one of the things your assessor looks for because I remember a few years ago during an assessment I was asked this exact question. And you shouldn't connect the two earthing arrangements together via the armourings.

 

[vickery1971]

Ah, thats interesting, people always slate TT'ing garages but never explain why. And i didint realise you need permission to export the suppliers earth . . . .you learn somthing new every day!
I always carry a few rods so i can stick one in, belt and braces i suppose.
And is there any reason you shouldnt connect the earthing arrangements both ends? (I usually only connect one end i just noticed a lot of people on garage posts saying do both)

Thanks for the advice

 

[onions1066]

Yes because you don't want an earth fault within the garage installation affecting the consumer rcd, keep the earthing separate, gland it consumer end and earth the armouring that end, In my opinion , good luck with assessor.

 

[Plonker 3]

By rights you should really install a rod for the garage, you shouldn't really export the suppliers earth out of the equipotential zone without there written permission, people will moan regarding this but that's the deal. That could be one of the things your assessor looks for because I remember a few years ago during an assessment I was asked this exact question. And you shouldn't connect the two earthing arrangements together via the armourings.

What complete and uttet tosh. Find me a rule or regulation that says exporting a equipotential zone is not allowed.

 

[shocking_eg]

Soo many rumours regarding exporting suppliers earths it's ridiculous !!

Your 'extending' not exporting your equipotential zone so nothing wrong with that.

Why would you opt for a crappy TT when you have a much lower earthing system already !

 

[vickery1971]

Hmmmmm thanks for the input chaps . . . . .

So in your opinion, would what I plan to do in my OP be adequite?

Im probably going to start another debate but im just trying to get this job as near to 100% right as i can, after all, how can those of us with fewer years under our belts learn if we are too scared to ask the learned ones among us.

Ohhhhhh its snowing again