How would you.....?

[kme]

Scenario is:

160A TPN supply, needs to feed two DBs; one of which is being replaced.

The supply conductors will be 70mm (SWA/XLPE)

The board to be replaced is within 3 metres of the local isolation for the supply; the other is approx 10 metres away from the first board.

The furthest DB requires an 80A/phase supply - plan was to use 35mm SWA as a sub - but that is going to need fusing down from 160A

I don`t have the space to introduce a full panelboard - so I can`t sub it from the "new" board on an MCCB

An 80A switchfuse won`t take ONE 70mm, let alone two of `em.

So the choices are:

1. A stand-alone MCCB enclosure - lug the 70mm onto the MCCB, and take the 35mms off to the 2nd DB

2. Take the 70mm into the new DB, then run 35mm internally through to the S/F, and go from there - but where can the 35mm be connected? (Dorman smith DB)

3. Do something completely different!!!

Your thoughts would be appreciated.

KME

 

[park1]

Do something completely different.

Can you not just put a 80 amp MCCB as the incomer of the Dorman smith?

---------- Post Auto-Merged at 14:31 ---------- Previous post was made at 14:15 ----------

Or better still considering discrimination, just run 35 into a 80 s/f

 

[kme]

Yes, I could - because the DS board will only need 80A

BUT...so will the other DB.....and you can`t GET an MCB larger than 63A - and I can happily draw more than that at any given time.

somewhere I need to split the feed to the 2nd board.

I think it`ll be option 2, tbh......

 

[park1]

Yes, I could - because the DS board will only need 80ABUT...so will the other DB.....and you can`t GET an MCB larger than 63A - and I can happily draw more than that at any given time.

somewhere I need to split the feed to the 2nd board.

I think it`ll be option 2, tbh......

Sorry KME I meant MCCB.

The 70mm is protected at the origin i assume? This runs to the first DB? what's the incomer?

Is it not possible to take a 35 mm from the first Db and take it to a 80 amp switch fuse, then run that to the isolator of the 2nd Db.

 

[ElectekAir]

Why can't you install a 250a TP isolator. With small buzz bar chamber then two isolators from that to connect the two DB's, may not be the cheapest option tho

 

[kme]

Just had a chat with the Dorman Smith rep.........

They had a kit for coming straight off the internal busbars of the DB, out to a single MCCB enclosure.

Which will solve the whole issue quite neatly - I don`t have to split the 70mm anywhere - they can go straight into the D/S DB

Then the external MCCB can take the 35mm off to the second DB.....

Happy daze

Thanks all for the responses.

:x

KME

p.s. $park - the 70mm isw coming from a 200A TPN iso, protected on the furthest end by 160A BS88s

The D/S incomer is a 160A switch disconnect

Elec: That would work - though the two issues are the possible cost, and space!!!!!