- Reaction score
- 3,010
The company is in the process of dropping a gable end which requires many circuits being cut back and then reinstated.
I advised we do an EICR, although not due and for info only, to get a baseline on the installation before we start ripping it to pieces.
It was approved and despite the age and some iffy spurs it's in remarkable condition.
One thing that stood out was at the main DB and two sub boards the the ZDBs were very low giving PFCs in the range of 3-6KA
All the boards are populated with Hager two module RCBO which have a breaking capacity of 4000A.
Those in DB1 will almost certainly be under rated.
The other two DBs though have an additional 10mm earth run back to DB1 alongside the 16mm T&E sub main. Removing this brings the ZDBs up to sensible levels.
The incomer is TP TN-S with only one phase in use.
Is it likely that originally the Ze was much higher and external DNO works have brought this down, hence the additional 10mm earth?
Obviously I have no access to any previous results.
I advised we do an EICR, although not due and for info only, to get a baseline on the installation before we start ripping it to pieces.
It was approved and despite the age and some iffy spurs it's in remarkable condition.
One thing that stood out was at the main DB and two sub boards the the ZDBs were very low giving PFCs in the range of 3-6KA
All the boards are populated with Hager two module RCBO which have a breaking capacity of 4000A.
Those in DB1 will almost certainly be under rated.
The other two DBs though have an additional 10mm earth run back to DB1 alongside the 16mm T&E sub main. Removing this brings the ZDBs up to sensible levels.
The incomer is TP TN-S with only one phase in use.
Is it likely that originally the Ze was much higher and external DNO works have brought this down, hence the additional 10mm earth?
Obviously I have no access to any previous results.