Twin and earth used as meter tails

[plancaster]

Hell lads I wish I never posted it

 

[Mark Wright]

it's something I've wanted to look at for some time because you often hear about sizing Earthing conductor and Tails with adiabatic

ok IF my calc is correct

S = √580²*5
------------ = 9.07 - 10mm
143

and

t = 143²*10²
-------------- = 6.08 Seconds
580²

Does that look right?

 

[pc1966]

Does that look right?

Yes, they look right to me

 

[Mark Wright]

Ok so with 10mm it is just about ok 6.08seconds the fuse should blow ??

6mm 2.18 seconds so 6mm not really ok.

Is this fault current realistic?

 

[pc1966]

It is a realistic fault current as may places will have PFC of around that, but the majority of cases you are looking at the 0.4s disconnection times on a MCB for a final circuit so you are seeing much less energy.
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For example, few domestic circuits will have above a 50A B-curve MCB and that has the instantaneous trip at no more than 250A

 

[Mark Wright]

It is a realistic fault current as may places will have PFC of around that, but the majority of cases you are looking at the 0.4s disconnection times on a MCB for a final circut so you are seeing much less energy.

Thank you sir your much better than my teacher, have a good day.

 

[static zap]

Hell lads I wish I never posted it

Fear not -We always enjoy an Eduction-

Anything hanging on a long length of t&e ...
is Doomed to become a "Shed-thread"
(must brush off my Scot's accent - 'Dad's Amy style')