maximum demand per phase?

[round the bend]

hi there, sorry for being such a "girl" but I've just had a new fuseboard put in, on the certificate the electrician gave me it states that the maximun demand per phase is 60 amps if I've got 3 x 32 amp fuses & 2 x 40 amps plus other small ones how can this be? The electrician didn't really explain it. Can anyone help a lady (who is now quite worried!)?

 

[GaryMo]

It will be based on you having a 60A supply and that being the maximum your installation should consume at any one time.
What are the two 40A supplies? Cooker and shower?

You may well require a supply upgrade to 100A (if it's possible) dependant on potential loading.

 

[fireman22]

well its down to a diversity thing where all circuits wont be used to their full value at the same time and i guess your fuse is a 60A so he has stated the value of the fuse. i will get my clamp meter and do a few tests throughout today (everyone and their friend seems to be here on a sunday) and will post highest reading later

 

[fireman22]

just did a reading 2.2 amps. only one light on understair one to see the clamp meter one tv computers laptop charger and two million standby LED`s of course!

 

[Lectrician]

It will be based on you having a 60A supply and that being the maximum your installation should consume at any one time.
What are the two 40A supplies? Cooker and shower?

You may well require a supply upgrade to 100A (if it's possible) dependant on potential loading.

Now thats gone and scared them!

Seriously - if you have never had a loading issue, why would you go through the hassle of requesting an upgrade?

I know my DNO would laugh if I requested an upgrade to a bog standard domestic! My DNO fit an 80amp as standard, and if you want 100amp or more, the cutouts are larger, and obviously anything above 100amp is then CT metered.

60amp is approaching tight for a domestic - but dont rock the boat.

 

[GaryMo]

Depends what the two 40A supplies are. If they're both electric showers in a family home then there's a good likelihood they will both be used at the same time.
I'm saying this as recently I talked a customer out of fitting a second electric shower due to him only having a 60A supply.

 

[Stoday]

If you ask the DNO to upgrade your demand, you may have to pay for it. The DNO might want to lay some extra distribution cable or change a transformer. You could end up paying for it.

So don't ask. If you blow a 60A fuse on overload the DNO will replace it, maybe with one with a higher rating.

 

[Steve3948]

60A HBC will take 180-300A before blowing under load.