Since we're on electrics again I thought I'd throw another quickie in too. I've been right through estimating maximum demand for the house and the workshop.
My supply is 80A, but it'll be feeding three consumer units when the dust settles - the house, the original workshop CU, and another I'm installing to hold enough MCBs to power my machines on radial circuits.
This seems to be OK practice, but it has the effect of leaving the situation so that far more power can be drawn than the incoming service fuse can handle - if more circuits are loaded more than the max demand estimate presumes.
Would it make sense in this situation to feed all of the incoming power through an 80A type C breaker to protect the service fuse (HRC fuses it seems can tolerate pretty heavy overloading anyway), and enable easy shut down of all power to the house?
Plan B is just to leave it all alone, and rely on the butch nature of these fuses - it looks from the data sheet that they can handle well over 100A for quite an extended period anyway. Trouble is that if it does let go getting involved with the service provider (an ex state monopoly) tends to be ruinously expensive.
A few related practical questions.
Is meter tail the type of single core cable used to wire inside a consumer unit?
If so should it be colour coded - blue/brown/green yellow as normal? (I've seen some that are not)
What mm2 sizes are required to handle 60A and 80A? - the sizing tool on the TLC doesn't seem to cover this.
How is the earth cable sized - the same mm2 as the L&N conductors?
This new CU will have all of the 16A dedicated machine circuits, the 30A rotary converter, the 30A dust system fan motor inverter (these can't usually be used with an RCD) plus the 13A workshop sockets (split in two ring mains) wired from it - about 9 circuits.
Should it use/not use an RCD on the circuits other than the inverter? (i.e. be a split unit) Will the 5.5kW rotary converter pop RCDs? Nusiance tripping from this and the other circuits is the concern
My supply is 80A, but it'll be feeding three consumer units when the dust settles - the house, the original workshop CU, and another I'm installing to hold enough MCBs to power my machines on radial circuits.
This seems to be OK practice, but it has the effect of leaving the situation so that far more power can be drawn than the incoming service fuse can handle - if more circuits are loaded more than the max demand estimate presumes.
Would it make sense in this situation to feed all of the incoming power through an 80A type C breaker to protect the service fuse (HRC fuses it seems can tolerate pretty heavy overloading anyway), and enable easy shut down of all power to the house?
Plan B is just to leave it all alone, and rely on the butch nature of these fuses - it looks from the data sheet that they can handle well over 100A for quite an extended period anyway. Trouble is that if it does let go getting involved with the service provider (an ex state monopoly) tends to be ruinously expensive.
A few related practical questions.
Is meter tail the type of single core cable used to wire inside a consumer unit?
If so should it be colour coded - blue/brown/green yellow as normal? (I've seen some that are not)
What mm2 sizes are required to handle 60A and 80A? - the sizing tool on the TLC doesn't seem to cover this.
How is the earth cable sized - the same mm2 as the L&N conductors?
This new CU will have all of the 16A dedicated machine circuits, the 30A rotary converter, the 30A dust system fan motor inverter (these can't usually be used with an RCD) plus the 13A workshop sockets (split in two ring mains) wired from it - about 9 circuits.
Should it use/not use an RCD on the circuits other than the inverter? (i.e. be a split unit) Will the 5.5kW rotary converter pop RCDs? Nusiance tripping from this and the other circuits is the concern