Single Phase Fault Current

[Elekk]

If the available 3-phase prospective fault current at 3-Phase busbar is 16kA, a three phase fuse rated for 16KA or more will be required at this busbar.

Then if we have to connect a single phase (line to neutral) fuse at one of the phases of the same busbar, should this single phase fuse be also rated for at least 16kA?

 

[septiclecky]

You can't get a 3 phase fuse, it is the same fuse you use for single phase.

 

[kme]

I assume the O/P was referring to a multi pole MCB mate

For SP, division by two, as Canoe suggests.

 

[Elekk]

Canoe and Kme, is there some document on internet where I can see this rule of thumb (divide by 2 to get single phase short circuit current). I know you are correct, but just want to confirm.

 

[steptoe]

I cant remember but at a guess if its not in the BRB then its probably in GN3, i stand to be corrected though!!

I'm sure SL will be along to give us the page number :slap

or write the page for you.

 

[philbas]

Its in GN3, bottem of page 52.

It's the other way around, but i'm sure we can all transpose the equation

 

[Elekk]

Is there some website where I can buy the pdf copy of GN3?

 

[SPECIAL LOCATION]

I cant remember but at a guess if its not in the BRB then its probably in GN3, i stand to be corrected though!!

I'm sure SL will be along to give us the page number :slap

And I thought you would have the guidance notes there as e-books to instantly cross reference on your all singing and dancing Mac!!!

Is that something a Mac can't do?? ] :C :slap:slap:slap:slap

---------- Post Auto-Merged at 00:41 ---------- Previous post was made at 00:40 ----------

Its in GN3, bottem of page 52.It's the other way around, but i'm sure we can all transpose the equation

Concur :Salute

---------- Post Auto-Merged at 00:42 ---------- Previous post was made at 00:41 ----------

Is there some website where I can buy the pdf copy of GN3?

AFAIK there is no PDF..

there is the e-book option...

but it ain't cheep... (part of a bigger package! :| )

Wiring Regulations Digital - IET Electrical

If I were you I would just go to Amazon or similar and buy the "real" book!

Amazon.co.uk: guidance note 3

 

[septiclecky]

And I thought you would have the guidance notes there as e-books to instantly cross reference on your all singing and dancing Mac!!!Is that something a Mac can't do?? ] :C :slap:slap:slap:slap

Well MACs don't sound all that good then do they:yawn:yawn:yawn

 

[philbas]

ok, ive just thought about this a bit more, not sure you can just transpose the equation.

Doubling up the single phase PFC will err on the side of safety, but the other side of this is halving the three phase level will err on the side of not safe. I hope that makes sense