3 phase supply, advice required

[lurch]

Some advice please. . . I have a local community centre (old prefab) that has a 3 phase TNS supply from the local DNO. I have carried out a EICR which has unsatisfactory on various points, however I am trying to locate the regulation that covers isolation. . . . the scenario is 3 phases in to 3 phase meter, and then 3 separate single phase domestic Consumer units, all located within a cupboard.

My concern is that there is no single point of isolation on the 3 phase supply. I want to give this a C2 but not having come across this scenario before and want to know the regulation that covers this . . . if there is one. Or is it totally acceptable to have this setup as it is. . . . constructive answers always welcome.

 

[telectrix]

i'd C3 it if all 3 CUs were together. a TPN isolator would be beneficial, but a notice stating that each SP board was independently isolated may suffice.

 

[Pete999]

Some advice please. . . I have a local community centre (old prefab) that has a 3 phase TNS supply from the local DNO. I have carried out a EICR which has unsatisfactory on various points, however I am trying to locate the regulation that covers isolation. . . . the scenario is 3 phases in to 3 phase meter, and then 3 separate single phase domestic Consumer units, all located within a cupboard.

My concern is that there is no single point of isolation on the 3 phase supply. I want to give this a C2 but not having come across this scenario before and want to know the regulation that covers this . . . if there is one. Or is it totally acceptable to have this setup as it is. . . . constructive answers always welcome.

You have 3 points of isolation 1 on each Consumers Unit.

 

[lurch]

see pic for info

 

[lurch]

You have 3 points of isolation 1 on each Consumers Unit.

agreed. . . but Ive always had it drummed into me from way back that there should be a single point of isolation in the event of an emergency

 

[Pete999]

agreed. . . but Ive always had it drummed into me from way back that there should be a single point of isolation in the event of an emergency

You would be extremely unlucky to have an emergency on all SP&N CUs at once Lurch, think the isolation matter is covered. Remember it may be a 3 phase supply, but all you have is 3 SP&N Systems

 

[Steve Bramah]

Some advice please. . . I have a local community centre (old prefab) that has a 3 phase TNS supply from the local DNO. I have carried out a EICR which has unsatisfactory on various points, however I am trying to locate the regulation that covers isolation. . . . the scenario is 3 phases in to 3 phase meter, and then 3 separate single phase domestic Consumer units, all located within a cupboard.

My concern is that there is no single point of isolation on the 3 phase supply. I want to give this a C2 but not having come across this scenario before and want to know the regulation that covers this . . . if there is one. Or is it totally acceptable to have this setup as it is. . . . constructive answers always welcome.

If it was my job, i would fit a 4 pole 100a isolator, much the same as your electrical utilities supplier would fit. Not expensive, and sorts out the "one point of isolation" reg. Hope this helps.

 

[Ian1981]

It’s not potentially dangerous at all so it’s no chance a C2

 

[lurch]

You would be extremely unlucky to have an emergency on all SP&N CUs at once Lurch, think the isolation matter is covered. Remember it may be a 3 phase supply, but all you have is 3 SP&N Systems

agreed. . . but all it takes is for joe public to look in cupboard and isolate wrong board. . . I like to make life simple for 'em. Furthermore, if boards were sited in 3 separate locations I get it, but if I were to do this job from scratch it would be a TPN bioard end of . . . . but that's not the case.

 

[Pete999]

If it was my job, i would fit a 4 pole 100a isolator, much the same as your electrical utilities supplier would fit. Not expensive, and sorts out the "one point of isolation" reg. Hope this helps.

Not a bad idea Steve, but if you relyon the Isolator you mention as the single point of isolation, problem occurs in one particular SP system, then you would isolate all three CUs. Just a thought.

 

[freddo]

We replaced the DBs in a similar setup, fitting a 4 pole isolator marked installation main switch. This was the last job we ever used MK consumer units.

 

[Steve Bramah]

You would be extremely unlucky to have an emergency on all SP&N CUs at once Lurch, think the isolation matter is covered. Remember it may be a 3 phase supply, but all you have is 3 SP&N Systems

Hi Pete, I don't think it makes any difference whether its a 3 phase supply or a single phase!
A local plumber in Prestwich,Manchester turned off the consumer unit, because he was going to change the shower. What he didn't spot was a Wylex 104 in the corner of the mains cupboard. Consequently, the world is one plumber less.

 

[Pete999]

Hi Pete, I don't think it makes any difference whether its a 3 phase supply or a single phase!
A local plumber in Prestwich,Manchester turned off the comsumer unit, because he was going to change the shower. What he didn't spot was a Wylex 104 in the corner of the mains cupboard. Consequently, the world is one pluber less.

Could happen anywhere switching off the wrong Mains Switch, just an important question, was the Plumber trained in the Safe Isolation Procedure? seems not in this
instance.

 

[lurch]

Hi Pete, I don't think it makes any difference whether its a 3 phase supply or a single phase!
A local plumber in Prestwich,Manchester turned off the consumer unit, because he was going to change the shower. What he didn't spot was a Wylex 104 in the corner of the mains cupboard. Consequently, the world is one plumber less.

this highlights the point I am making. . . if there was a single point of isolation then this wouldn't of happened. we are obsessed in this country on cutting into meter tails and hooking in additional cu's .

 

[lurch]

Could happen anywhere switching off the wrong Mains Switch, just an important question, was the Plumber trained in the Safe Isolation Procedure? seems not in this
instance.

clearly not.

 

[lurch]

It’s not potentially dangerous at all so it’s no chance a C2

I guess that is down to intrrpretation

 

[Deleted member 105166]

Digressing slightly, this is a rather decent supply for a community centre, compared to many.

 

[Dillb]

Hi Pete, I don't think it makes any difference whether its a 3 phase supply or a single phase!
A local plumber in Prestwich,Manchester turned off the consumer unit, because he was going to change the shower. What he didn't spot was a Wylex 104 in the corner of the mains cupboard. Consequently, the world is one plumber less.

As Pete mentioned he obviously didn’t follow the correct procedures, a simple voltage tester would of saved him yet he got complacent.

 

[Dillb]

Hi Pete, I don't think it makes any difference whether its a 3 phase supply or a single phase!
A local plumber in Prestwich,Manchester turned off the consumer unit, because he was going to change the shower. What he didn't spot was a Wylex 104 in the corner of the mains cupboard. Consequently, the world is one plumber less.

As Pete mentioned he obviously didn’t follow the correct procedures, a simple voltage tester would of saved him yet he got complacent.

 

[lurch]

It’s not potentially dangerous at all so it’s no chance a C2

I guess that is down to intrrpretation

 

[lurch]

I guess that is down to intrrpretation

but if there is no reg that covers it then yes C3

 

[Ian1981]

Each consumer unit has a means of isolation to their respective circuits.
I can’t see how not having a single point of isolation may result in potential danger to the user of the installation of anyone else.

 

[lurch]

Digressing slightly, this is a rather decent supply for a community centre, compared to many.

my thoughts exactly . .. however there is no gas and all water/heating is 3 kw immersions and fan units, and the cut outs at 60amp BS88s

 

[Steve Bramah]

clearly not.

Now we are moving into the realms of assuming that everyone is foolproof, just because they are a tradesman. Today's "super regs" have been drawn up, assuming that everyone that's not electrically qualified is a moron. The incident i brought up happened in the days before thins like RCDs MCBs etc, but a single point of isolation would have saved his life.

 

[lurch]

We replaced the DBs in a similar setup, fitting a 4 pole isolator marked installation main switch. This was the last job we ever used MK consumer units.
View attachment 41620

. . . hahah sounds like your view of MK is a little like mine. . . rubbish!!