Two pairs of tails from meter to two DB's - what do I record in Section L?

[Gentle Ben]

Evening all, been a long time since I posted on here but I could use some advice if there's any going!

I've been asked to provide an EICR for a small building we look after for our client under contract. We are all done physically on site, but I've hit a snag filling out the report itself, in particular with Section L - Particulars of Installation at the Origin.

There is a small cupboard with the supply cable / cut-out / meter. The tails travel from the meter into an insulated adaptable box, and two pairs of tails come out, each pair feeding it's own three-phase x 8-way D - 24 circuits per DB / 48 circuits for the whole building.

Each DB has an RCD as a Main Switch - historically the supply to DB2 was taken out of DB1 as a sub-main supply. However due to problems with the 100A RCD main switch for DB1 tripping almost daily due to overload, due to it carrying the load for both DB's, we decided to put DB2 on its own supply from the meter a year or two ago.

This solved the overload problem, but now I have a problem filling out the details of the Main Switch - under the new configuration, there is, I would suggest no Main Switch as such - at least, there is no longer a single switch that can isolate the whole building / installation.

So is it a case of writing N/A in the boxes because there is no main switch?

Also, does the lack of a main switch breach BS7671? Should it be coded in Section F and if so how should it be coded?

Any advice would be gratefully received...

Thanks

Ben

 

[Risteard]

It's not necessarily a breach of BS7671 as these could be classed as two installations.

 

[westward10]

I disagree, historically it was one installation and still is as there is only one source of supply. By rerouting the supply for DB2 you have created two means of isolation not two installations.

 

[telectrix]

i'd enter a star in the box.note at bottom of page.....
see schedule DB1 & schedule DB2.

then on each schedule enter details of each main switch.

 

[Gavin John Hyde]

I would record the principle db as having main switch and maybe on the schedule of results for db2 record the isolation method on there. I stopped over thinking these things and now make free use of the comments box. Especially is using niceic forms.

 

[westward10]

It has no main switch however you dress it up.

 

[Strima]

I would class this as one installation with no single point of isolation.

 

[Richard Burns]

I would also specify the installation as having no single point of isolation and therefore no main switch to specify in the origin of the installation. However the main switch for each DB can be entered in the schedule of test results.
I tend to think that no single point of isolation when the DBs are all in the same location is not too critical and would specify it as a C3 improvement recommended, since it is clearly required with no ambiguity in BS7671. If there were widely separated DBs with no single point of isolation this becomes more dangerous and may attract a C2. In your case it is an easy resolution to fit an isolator at the adaptable box position.

 

[PEG]

Evening all, been a long time since I posted on here but I could use some advice if there's any going!

I've been asked to provide an EICR for a small building we look after for our client under contract. We are all done physically on site, but I've hit a snag filling out the report itself, in particular with Section L - Particulars of Installation at the Origin.

There is a small cupboard with the supply cable / cut-out / meter. The tails travel from the meter into an insulated adaptable box, and two pairs of tails come out, each pair feeding it's own three-phase x 8-way D - 24 circuits per DB / 48 circuits for the whole building.

Each DB has an RCD as a Main Switch - historically the supply to DB2 was taken out of DB1 as a sub-main supply. However due to problems with the 100A RCD main switch for DB1 tripping almost daily due to overload, due to it carrying the load for both DB's, we decided to put DB2 on its own supply from the meter a year or two ago.

This solved the overload problem, but now I have a problem filling out the details of the Main Switch - under the new configuration, there is, I would suggest no Main Switch as such - at least, there is no longer a single switch that can isolate the whole building / installation.

So is it a case of writing N/A in the boxes because there is no main switch?

Also, does the lack of a main switch breach BS7671? Should it be coded in Section F and if so how should it be coded?

Any advice would be gratefully received...

Thanks

Ben

 

[PEG]

Hi,just out of interest,how did the RCD letting go,become an overload issue?
Or do you mean "over-leakage"?

 

[Risteard]

I disagree, historically it was one installation and still is as there is only one source of supply. By rerouting the supply for DB2 you have created two means of isolation not two installations.

I don't disagree, but IET Guidance Notes specifically state that they can be considered to be separate installations and therefore don't need a common isolator.

 

[Andy78]

I don't disagree, but IET Guidance Notes specifically state that they can be considered to be separate installations and therefore don't need a common isolator.

If it is worded "can" be considered to be separate, then surely you can consider it otherwise too ?
"Must" or "Should" would indicate differently though.

I always define an installation by the incoming supply myself. My choice based on the vague definition of "installation" in the regs.

 

[ipf]

I would class this as one installation with no single point of isolation.

...as is the case with Henley blocks feeding more than one db....not two installations, surely?

 

[ipf]

I've got one ...an old church 3 ph intake to various single ph supplies, all fed from connection blocks. Tails to local boards and switches with pyros and swa's out to remote boards.
No way can they afford to pay for a main switch and busbar chamber job......plus there's no room to fit it anyway.
NIC bloke's coming later in the month so I might just give it a mention to get him thinking and see what he comes up with...and waste a bit of time.
edit. Wonder if he'll recommend a failure......and shutting them down?
For me it's a note saying individual isolation incorporated on db schedules.

 

[Andy78]

I've got one ...an old church 3 ph intake to various single ph supplies, all fed from connection blocks. Tails to local boards and switches with pyros and swa's out to remote boards.
No way can they afford to pay for a main switch and busbar chamber job......plus there's no room to fit it anyway.
NIC bloke's coming later in the month so I might just give it a mention to get him thinking and see what he comes up with...and waste a bit of time.
edit. Wonder if he'll recommend a failure......and shutting them down?
For me it's a note saying individual isolation incorporated on db schedules.

I think Richard Burns had a good point earlier on, that if all the points of isolation are in the same location then that is a different situation to them being scattered about an installation.

 

[telectrix]

could always replace the adaptable box splitter with a TP&N isolator, thus making a single point of isolation for both DBs.

 

[Wilko]

It has no main switch however you dress it up.

Agree. I was at a house last week to quote on some lights. In the attached garage I found 3 CUs. A 6 fuse original and two 2s. So 3 isolators and the top one about 8ft up... All spaghetti tails from blocks. And the circuit they want modified has no RCD. We'll see what happens ...

 

[ipf]

I think Richard Burns had a good point earlier on, that if all the points of isolation are in the same location then that is a different situation to them being scattered about an installation.

Then we get into the 'length of tails' issue, though.

 

[Toneyz]

What is the main fuse size?

 

[the pict]

I've got one ...an old church 3 ph intake to various single ph supplies, all fed from connection blocks. Tails to local boards and switches with pyros and swa's out to remote boards.
No way can they afford to pay for a main switch and busbar chamber job......plus there's no room to fit it anyway.
NIC bloke's coming later in the month so I might just give it a mention to get him thinking and see what he comes up with...and waste a bit of time.
edit. Wonder if he'll recommend a failure......and shutting them down?
For me it's a note saying individual isolation incorporated on db schedules.

Oh Yes and let him incur the wrath of the almighty,serve the bugger right