Do I need a TP&N fused isolator?

[JosephandAmber]

So the situation is this:

Historic 4 story townhouse to 4 flats conversion.
Supplier 3-phase cut out coming in at basement level (One of these will have a 60amp fuse, unsure whether the other 2 contain solid links or additional 60amp fuses yet).
1 phase feeding basement.
4-core SWA containing 2 phases + N&E about 10m in length feeding a Ryefield on 1st floor (UKPN describe this as a riser).
Ryefield contains 3 x 60A fuses with 16mm T&E sub mains feeding CUs in flats.

Now my question is:
Do I need a TP&N fused isolator installed just after the cut-out protecting the riser, which in turn feeds the Ryefield? My current thinking is if cut out contains solid links then yes, if it contains 60 fuses then no - otherwise you're going to have 3 x 60 fuses on each conductor within 10m of cable.

 

[Pete999]

So the situation is this:

Historic 4 story townhouse to 4 flats conversion.
Supplier 3-phase cut out coming in at basement level (One of these will have a 60amp fuse, unsure whether the other 2 contain solid links or additional 60amp fuses yet).
1 phase feeding basement.
4-core SWA containing 2 phases + N&E about 10m in length feeding a Ryefield on 1st floor (UKPN describe this as a riser).
Ryefield contains 3 x 60A fuses with 16mm T&E sub mains feeding CUs in flats.

Now my question is:
Do I need a TP&N fused isolator installed just after the cut-out protecting the riser, which in turn feeds the Ryefield? My current thinking is if cut out contains solid links then yes, if it contains 60 fuses then no - otherwise you're going to have 3 x 60 fuses on each conductor within 10m of cable.

Why only 2 phases ?

 

[JosephandAmber]

Why only 2 phases ?

So the three-phase incoming supply has been split as follows:
Phase 1 > basement flat CU
Phase 2 > 1st-floor Ryefield > ground floor CU + first floor CU
Phase 3 > 1st-floor Ryefield > second floor CU

The SWA needs re-doing and tbh I think I'll spec an additional core to bring all three phases up to the ryefield anyway. Just allows for more options in the future.

 

[Pete999]

So the three-phase incoming supply has been split as follows:
Phase 1 > basement flat CU
Phase 2 > 1st-floor Ryefield > ground floor CU + first floor CU
Phase 3 > 1st-floor Ryefield > second floor CU

The SWA needs re-doing and tbh I think I'll spec an additional core to bring all three phases up to the ryefield anyway. Just allows for more options in the future.

Are you not using the sheath bas the Earth then?

 

[buzzlightyear]

Did you take any pics, of this work that is needed.

 

[JosephandAmber]

Are you not using the sheath bas the Earth then?

The current install is a mess hence the work. 4 core SWA being used as a riser to Ryefield (2 phases, N and E).

 

[JosephandAmber]

Sorry if people are struggling to follow me on this one.

In short, normally you'd want to have a fused isolator on a sub main. Do you however need to do this for a 'riser', given its not DNO property but sits after their cutout fuses and before the Ryefield, again with its own main fuses?

 

[Pete999]

The current install is a mess hence the work. 4 core SWA being used as a riser to Ryefield (2 phases, N and E).

Bit risky is that

 

[buzzlightyear]

60amp fuses yet).
1 phase feeding basement.
4-core SWA containing 2 phases + N&E about 10m in length feeding a Ryefield on 1st floor (UKPN describe this as a riser).

The riser in the 1st floor is this separate area, cause confusioned

 

[JosephandAmber]

The riser in the 1st floor is this separate area, cause confusioned

Yeah. 4 floor house. Power enters via basement, 1 phase being used for basement flat. Other 2 phases being taken to a ryfield on 1st floor to feed 3 flats above. Bit of a weird one I know as you've got the supply infrastructure split into two locations.

 

[JosephandAmber]

Currently waiting for UKPN to pick up the phone - hopeful for an answer from them as to the best way to approach this.

 

[Pete999]

Sorry if people are struggling to follow me on this one.

In short, normally you'd want to have a fused isolator on a sub main. Do you however need to do this for a 'riser', given its not DNO property but sits after their cutout fuses and before the Ryefield, again with its own main fuses?

Sorry if people are struggling to follow me on this one.

In short, normally you'd want to have a fused isolator on a sub main. Do you however need to do this for a 'riser', given its not DNO property but sits after their cutout fuses and before the Ryefield, again with its own main fuses?

Bit risky is that

2 phases to a three phase board you might want to consider your options Mate.