Submain with no isolation

[Tim]

Hi guys,

Im doing an eicr on a commercial site (offices) and have found 2 3phase db's fed strait from the main intake busbar.

1 run is only 2metres clipped direct armoured 35mm 4c

And 1 is 8m clipped direct above ceiling tiles armoured 25mm 4c

Am i right in saying they need a fused isolator or is there a reg that says the run is less than x metres and can be fed strait from the bus bar.

Thanks,
Tim

 

[Brightspark2]

What rating are the fuses feeding the bus bar?...

 

[Tim]

I cant fully open the isolator without turning off the entire building, from what i can see by undoing the screws and peering in to the 315a main isolator they are only links, no fuses.

Ill go take a pic of the intake layout.

 

[Tim]

I hope you can see the picture.

2 of the 3 armoured cables on the right feed the DBs mentioned the 3rd feeds an isolator for a seperate db in the cupboard.

The main isolator at the bottom is only an isolator, no fuses as far as i can see, i cant fully open it though.

Tim

 

[Brightspark2]

So what OPD is upstream of that?...

Over current protection can be placed within 3m of the change of CSA...so if the OPD is rated higher than the CCC of the cable feeding the DB 8m away then you have a problem...

The DB that is 3m away could be a problem too...is it just a main switch on the DB or does it have over current protection?...

 

[Tim]

Untill i can open the isolator i cant confirm 100% if or what OCPD is protecting the busbar. Im hoping i can get in at the weekend to check, from what little i can see though there are just 1" by 1/4" links, so only an isolator. The previous periodic says that there are 315a bs88 fuses in the enclosure, however i am sceptical as the previous electrician would likley also have not been able to open the isolator.

OCPD within 3m of change of CSA, thats the reg that i was think of but couldnt put my finger on, thanks.

The db that is only 2m away is only a main switch db, but as its under 3m, does it still need OCP, i would say yes it would but im going to the van to get the BGB to check.

The db 8metres away is definatly a problem. And having just gone back over the previous Periodic 5yrs ago the db was flagged up then as fed strait from the busbar.

Thanks for the help brightspark

 

[Brightspark2]

If the cable can be overloaded flag it up squire. You may just be able to swap the main switch for an OCPD.


Is it possible to protect the sub main within 3m though as theres no room in the cupboard lol.

 

[Tim]

I could not find a reg that said if the submain run is less than 3m it does not need OCP. So that is definatly going in the report with a recommendation to upgrade the db isolator to an OCPD as you said.




A picture through the gap, unless im very mush mistaken, these are not 315a bs88's, therefore the busbar is not fused.
i will note this down for further investigation as i cant open the main intake isolator (even at weekends now) to be 100% sure i havent missed something.

I hope that wraps up the thread, thanks brightspark.

Tim