What would you code this as.

[DefyG]

If the SWA gets damaged, ie L-E or L-N fault, I should imagine the current will be a lot more than 80A, possibly nearer 800A (irrespective of whatever mcb’s/circuits are connected downstream), resulting in a fried cable and an expensive replacement for the sake of proper over current protection.

 

[Vortigern]

We are talking short circuit @Electric i.e. 1Kv. You know, fault of neglible impedance, PSCC-PEFC????

 

[Julie.]

Im not saying these faults don't happen i'm asking about OP claiming the client was 'lucky' because the cable 'could pull 80a' because there's an 80a main fuse. I'm just talking about the installation as it is now not under a situation where it may develop a fault.

Isn't it only the equipment the other end that can pull 80a, which would never happen since it's lighting and sockets protected by 6 and 16 amp MCB's?

There is always the possibility of one of the downstream devices failing to trip - contacts weld together or the mechanism itself fails, upstream protection will limit the extent of an overload in these circumstances; nevertheless I would tend to agree, overload protection is probably not necessary on the swa, however fault protection still is, and as it's the same device its omission raises a c2.

The semantics aside the customer was lucky - especially given the numerous glaring issues that exist in merely this one photo.

 

[littlespark]

So you can do away with the 6A mcb for the lights as well as it will only be a fixed load of maybe 10W if LED? ?

It’s basic principles here…. MCB to protect the cable from fault as well as overload.

 

[Electrics]

So you can do away with the 6A mcb for the lights as well as it will only be a fixed load of maybe 10W if LED? ?

It’s basic principles here…. MCB to protect the cable from fault as well as overload.

I thought MCB's only protected overload and RCD's protected earth faults?

 

[Julie.]

I thought MCB's only protected overload and RCD's protected earth faults?

No

Rcds only protect for earth faults (actually unbalance), mcb will protect against overcurrent whatever the reason (phase - phase fault, phase - neutral fault, phase - earth/cpc fault and overload)

 

[7029 dave]

I thought MCB's only protected overload and RCD's protected earth faults?

Short circuit as well

 

[Electrics]

Thanks for the infos.

 

[Rockingit]

Is it just me or has this thread just revealed a tragic lack of understanding between fault protection and overload protection? This is basic stuff ladies and gents.

 

[loz2754]

Is it just me or has this thread just revealed a tragic lack of understanding between fault protection and overload protection? This is basic stuff ladies and gents.

True. But let's not forget that the main protagonists are trainees.