What's wrong here then?

[Badger]

erm surely thats cause its been unscrewed by you so the socket would be hanging off.

 

[springcrocus]

And Sellers has it apart from others who knew and only aluded to itYes, there's no High Integrity Earthing anywhere in the property,,,, even in the server room

And probably no RCD's in sight - they'd be tripping constantly, otherwise.

 

[gavindrummond]

Oh could you post a pic of how it should be?

 

[springcrocus]

Oh could you post a pic of how it should be?

Only if Noz has got a double socket in the van with two earth terminals on it!

 

[sellers]

RCD would still trip even with high integ earthing.

 

[springcrocus]

RCD would still trip even with high integ earthing.

You're right, of course. Fingers moving faster than the brain tonight. headbang

 

[NozSpark]

And probably no RCD's in sight - they'd be tripping constantly, otherwise.

They have two CU's upstairs fed from one unprotected 16mm T&E "sub main" via henly blocks directly off the tails and then a DP henly block and tails to the CU's

One them supplies 8 socket circuits,,, no RCD

the other supplies 10 lighting circuits and the alarm,,, no RCD

Downstairs CU is an old Square D one with a 4836 main switch RCD and 3871 type 2 MCB's

 

[gavindrummond]

I know this sounds stupid but as I'm a student I don't get it. Is it because it's a special location so the requirements are different when running cpc's?

 

[NozSpark]

I know this sounds stupid but as I'm a student I don't get it. Is it because it's a special location so the requirements are different when running cpc's?

Have a look at 543.7 in general and 543.7.2 in particular

Many things leak current to earth naturally, there is a requirement to terminate the cpc's into different terminals in ring circuits (even at the cu)

 

[sellers]

I know this sounds stupid but as I'm a student I don't get it. Is it because it's a special location so the requirements are different when running cpc's?

Its high integrity earthing, in areas where the are a lot of items that leak current to earth naturally it is needed. PC's generaly leak some current to earth, so imagine a computer room with 30 PC's in. It all adds up, so a bigger cpc is installed. I am not 100% clued up as to why, but I guess its to safely dissipate the current.

 

[NozSpark]

It's nothing to do with it being a special location,,, infact this particular one definately isn't

---------- Post Auto-Merged 8th May 2012 at 00:01 ---------- Previous post was made 7th May 2012 at 23:58 ----------

From reading the reg it doesn't have to be bigger, it just has to be seperate (for rings)

I think it's to do with maintaining an earth even if one terminal becomes loose

 

[SPECIAL LOCATION]

I know this sounds stupid but as I'm a student I don't get it. Is it because it's a special location so the requirements are different when running cpc's?

No it dosent...



THIS IS THE STUDENT AREA...



for people like you to get your head around things....

:Salute

It would be stupid if asked by a "competent" person in the inspection & testing area though!!!

:innocent

 

[sellers]

I suppose it makes perfect sense, loose you earth, and your PC case becomes 240v.

 

[gavindrummond]

Oh right I think I know what your on about I remember covering a little on that in collage but I will def check up on that thanks lads

 

[steptoe]

by a "competent" person

who you callin' competent.?!

you talkin' to me, eh? you talkin' to me?

 

[NozSpark]

No it dosent...

THIS IS THE STUDENT AREA...



for people like you to get your head around things....

:Salute

It would be stupid if asked by a "competent" person in the inspection & testing area though!!!

:innocent

That's exactly the reason I put it in here

 

[steptoe]

I suppose it makes perfect sense, loose you earth, and your PC case becomes 230v.

c'mon, keep up, we are harmonised now, and all our faults are at the same volts and current too, so when you get a shock you say mon dieu!

 

[Apache]

I suppose it makes perfect sense, loose you earth, and your PC case becomes 240v.

But I don't need a high integrity earth in my house and it's ok if I lose an earth connection and my PC case becomes live?

Are we saying that if each PC 'leaks' 5mA (making up numbers here, bear with me) that it is harmless to me even if I lost my earth. Set up 30 computers and you have 30X5 = 150mA that is hanging there unable to get a path to earth and if the cumulative current goes through me I might get more than a brief tingle?

Or is there another dimension to this going over my head?

 

[steptoe]

you are pretty much on the money 'pache

 

[sellers]

maybe the thinking of it takes 50mA (i think) to kill someone, with your 5mA PC, plus the resistance of your body meaning you are unlikely to be harmed. Where as 150mA has more potential for danger? Also your home if wired at the same time would have an RCD where as a room full or PC's more than likely won't