60 amp main fuse

[arturas]

I'm doing a new installation in a 4 bedroom house,basicaly it's 60 amp main fuse,if the client will turn every light,every appliance&load the sockets,im sure 60 amp wil be not enough.i told that to a client that he needs an upgrade from edf, but he says he doesn't want to because it will take some time and money,he just want to finish the house and sell it,he will say that he bought the house with this electric installation so he doesn't need a sertificate. I came with idea to instal a 60amp double pole isolator before CU so if the load would be bigger then 60 amp the isolator fuse would blow instead of main fuse and then he will definately need to upgrade the main fuse. Or should i just not connect the cu until he will upgrade it?thanks

 

[Knobhead]

OK I was being grumpy, but all I can do is go on is your OP and addendums. Things didn’t come through as well as they could do. But at the end of the day it’s first impressions that count, I did look at you’re previous posts before loosing the Exocet’s. Despite what you now may think of me now, I do have a heart and will help wherever I can. It just came down to something that’s dear to my heart which is cascading protection. It all comes down to a monumental row I had just after I came out of my time. A 630A fuse switch feeding a sub-board with a 630A fused incomer, I chucked the incomer fuses away and fitted solid copper links. I got my ares kicked by the foreman and told to refit the fuses. A couple of months down the road he came to me and gave me the links back and told me to fit them as I’d done originally. Apparently a fault on a deferent works had the same set up, red phase blown on the out going and yellow on the incoming. It caused endless confusion. Discrimination between equal fuses is like ----ing a coin in the air.

 

[telectrix]

now, i see the light. the negative comments made the assumption that you were out on your own, installing, and assuming that you didn't have sufficient knowledge/experience for that.

as regards cookers. the appliance usually limits what can be on at the same time, and also, each element is thermostatically controlled, so , say you had all 4 rings on at once, they would not all be drawing full load current at the same time. the 10A+30% has been good for 60 odd years.

 

[telectrix]

tony, i wasn't referring to you when i said grumpy.

 

[arturas]

For example which is in the OSG: let's say you have a cooker which is rated at 45 amps. so you can run 10mm twin& earth and put it on 50amp fuse . Or to cut the cost of the cable you could apply a diversity which will be: first 10a of rated current plus 30% of what's left and plus 5 amp if your cooker isolator comes with a socket outlet. so let's say there's no socket outlet. So your current demand to be assumed will be: 10amp + 30% of 35 amp= 10+10.5=25amp so basically you could use 6mm cable and put it on 32amp fuse, or even 4mm cable. There's another thing which would come in to: how long your cooker run will be , by which method you are installing your cable.

 

[Guest112]

agreed there can be some bad apples on this site ive found so far just ignore them

 

[londonlec]

Jesus.

 

[telectrix]

For example which is in the OSG: let's say you have a cooker which is rated at 45 amps. so you can run 10mm twin& earth and put it on 50amp fuse . Or to cut the cost of the cable you could apply a diversity which will be: first 10a of rated current plus 30% of what's left and plus 5 amp if your cooker isolator comes with a socket outlet. so let's say there's no socket outlet. So your current demand to be assumed will be: 10amp + 30% of 35 amp= 10+10.5=25amp so basically you could use 6mm cable and put it on 32amp fuse, or even 4mm cable. There's another thing which would come in to: how long your cooker run will be , by which method you are installing your cable.

well, yes. 6mm is rated at 47A clipped dircet, down to 31A if in thermally insulated wall, and if a long run volt drop has to be considered.