Single Point of Isolation

Help Support Talk Electrician Forum:

davetheglitz

Electrician
Joined
Mar 18, 2008
Messages
822
Reaction score
1
Location
Saltash, Cornwall
Can anyone help me with with understanding the regs on this - and how to score it on a PIR.

I did a PIR the other day and found the main fuse concealed behind a panel (with MET) and six seperate CUs all fed from Henley blocks.

My gut feeling is that in the event of an emergency you should be able to shut the whole system off easily and withdraw the fuse - but I can't find the regs to support this.

Is 'the single point of isolation' referring to the mains incomer - or just any group of circuits fed from a CU?

Can the fuse be considered as a point of isolation - and if it's not easily accessible is that covered by any regs?

How would you record this on a PIR?

Thanks

Dave

PS - love the idea of the forum - and it seems pretty slick - but is there a way of checking on the lates posts rather than date by thread?

 

welshwizard

Honorary Life Member
Joined
Feb 12, 2008
Messages
1,657
Reaction score
-1
PS - love the idea of the forum - and it seems pretty slick - but is there a way of checking on the lates posts rather than date by thread?

Thanks Dave.

With reagrds to the view new posts, the answer is yes, Mate.

To the left of where it says 'Log Out' above, you can see the New Posts Tab.

Regards,

Welshy.

 

SPECIAL LOCATION

Trailer Boy - Electrician.
Joined
Mar 28, 2008
Messages
13,633
Reaction score
317
My gut feeling is that in the event of an emergency you should be able to shut the whole system off easily and withdraw the fuse - but I can't find the regs to support this.

Try:-

Old flavour 16th 460-01-02 pg 63

New flavour 17th 537.1.4 pg 118

(them Bugge**s swapped the numbers around againX()

new regs table 53.2 pg 117

says a fuse e.g. BS88 is ok for isolation but NOT switching.

 

SPECIAL LOCATION

Trailer Boy - Electrician.
Joined
Mar 28, 2008
Messages
13,633
Reaction score
317
Back again!

forgot this bit..

How would you record this on a PIR?

I guess either 2 or 4..

it is not urgent, it dosn't need further investigation.

probably 4..

because there is a fuse that would disconnect under fault conditions.

and you can issolate the installtions by operating several switches.

i.e. although improvement would be preferable but not essential??

 

davetheglitz

Electrician
Joined
Mar 18, 2008
Messages
822
Reaction score
1
Location
Saltash, Cornwall
Thanks S.L. Yeah - thats my gut feel! :) (Sorry - generally hate smileys!!! :_| )

Regarding 537.1.4 (in new money) - this hinges on the definition of an electrical installation - an assembly of associated electrical equipment haviing co-ordinated characteristics to fulfil specific purposes.

This could mean a kitchen CU, 1st floor CU, Second floor CU etc - which is not what I would have understood by a single point of isolation - i.e. supply into a domestic property. I suppose you have to allow for factories etc where this obviously wouldn't be practical - so in essence you can interpret this any way you like.

I often feel that inspections are about common sense - and there are a lot of barack room lawyers out there who will qoute a regulation without any idea of its significance.

As an aside to all - if you haven't got hold of it them yet Electrical Safety Council Best Practice Guide on PIRs is brilliant and is available as a download - but it didn't cover this one!

 

biker mike

Senior Member
Joined
Feb 15, 2008
Messages
400
Reaction score
0
Location
Andover
I like that - not a lot - but I like it! (I'm suddenly feeling very old!)
youll all be reminiscing about rod hull next and his non bungee jumping antics

and where has emu gone ?????? what a fine bird she is :^O

 

SPECIAL LOCATION

Trailer Boy - Electrician.
Joined
Mar 28, 2008
Messages
13,633
Reaction score
317
Gawd - there`s a few old `uns on here ain`t there?Don`t feel quite so alone anymore.

Next you`ll be telling me you remember `phones with "A" and "B" buttons?????
As the thread gradually drifts off topic....

(there must be a mathematical formula somewhere as to how long a thread can run before is goes off topic.)

I propose this one...

[sm] - Subject mater- (gradded 1..10, where 1=boring 10=interesting)

[Np] - Number of posters

where 'Average No. of posts before thread drifts' = Sm x Np

e.g. medium suject interest grade 6, 4 posters

average posts = 6x4 before thread falls apart 24 posts!

Then you have correction factors'

[bCf] Beer correction factor = Np/average quantity of beer consumed by each poster

[sCf] Spirits correction factor = average alcohol volume% per poster.

[TCf] Time correction factor = number of hours past midnight!

So full formual......

'Average No. of posts before thread drifts' = ((Sm x Np) / BCf) x SCf x (1/TCf).

~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

going back to the original drift...

you`ll be telling me you remember `phones with "A" and "B" buttons

well....

I can say that in my time I have worked on Strowger telephone switching equipment, :eek: Uniselector machanical switches etc.. :eek:

cleaning relay contacts ... Arrrrrrggggghhhhhhh:O:O:O:O

 
Top