Overload Protection of "submain"

[Simon2021]

It's not referenced but the volt drop is from the source of supply to the end of your final circuits. If you use 2.2% on your distribution circuit that gives you only 0.8% to play with for lighting.

What is the expected maximum demand for the new build?

Thanks, I take your point, just looking at a 60w bulb at the end of a 50m lighting circuit the vd is 0.2%, everything is led lighting so I reckon this will still be within.

well without the kiln... and with diversity.... 54 amps is the number i am getting to, which seems low so im not certain im calculating it correctly divide the total of mcb's by 1.4?

 

[Simon2021]

nope thats wrong, 102, being 144/1.4,

 

[Strima]

If this is a domestic dwelling 54 amps is pretty high.

How many rooms? Electric water heating etc? EV charging point?

 

[Simon2021]

If this is a domestic dwelling 54 amps is pretty high.

How many rooms? Electric water heating etc? EV charging point?

yes, it is just a 3 bed bungalow, no ev, no water heaters.

Ive just revisted my books and now have it at 80amps with the diversity.

Theres a 32a RF, 1x 20A Radial, 2 6A light circuits, 16A boiler, 32amp oven and 32 amp hob.

I followed the onsite guide method (making assumptions about the size of cooker and hob) and it comes out at 80 amps

 

[MJPD29]

yes, it is just a 3 bed bungalow, no ev, no water heaters.

Ive just revisted my books and now have it at 80amps with the diversity.

Theres a 32a RF, 1x 20A Radial, 2 6A light circuits, 16A boiler, 32amp oven and 32 amp hob.

I followed the onsite guide method (making assumptions about the size of cooker and hob) and it comes out at 80 amps

Even at that you'll probably rarely if ever be near 80a at any given time

 

[Simon2021]

Even at that you'll probably rarely if ever be near 80a at any given time

I agree, its unlikely. My only concern was if they added this kiln in at some point in the future, 63a probably wouldnt be enough to use at the origin.

 

[Darkwood]

Do we have any info on the Kiln, hobby Kilns are not often heavy on demand and some run on standard plug tops, or are we looking at a commercial Kiln here?

 

[Simon2021]

No... But a 6mm cable had been left under the floor in preparation so it won't be a 13amp kind.

The main thing here is can I use the 80amp kmf as suggested earlier. I guess I could put it on a 63a MCB from the head and see if it holds.

 

[Darkwood]

You could but that could be breaching BS7671 about small overloads for long periods, however given the cable size shouldn't see it having any detrimental effects under said small overload it may merely contravene design and the avoidance of nuisance tripping but of course you can always visit when the Kiln lands an get a better idea.