Main Switch question!

[niloc1]

New to the trade and lots to learn! So I've filled in my very first installation certificate - but what is the Type BS(EN) of the main switch on this BS3036 semi-enclosed fuses consumer unit? It's 250V, 80A but no more markings - is it relevant for this old board? Also why does my tester not display the PFC in kA as asked for on the form - I get 0.17 ohms. Help!

niloc1

 

[ajelec10]

The bs no. is probaly 5419 which has now been superceeded by bs en 60947-3 on newer cu's as for the pfc this is the prospective fault current i think they require it from phase to earth so ohms law 230/0.17 gives you the current,
Hope this helps
AJ

 

[Darkwood]

If your meter dosn't have a pfc test option just divide your 0.17 into the line voltage to get you pfc in amps then divide this into 1000 for Ka

 

[niloc1]

The bs no. is probaly 5419 which has now been superceeded by bs en 60947-3 on newer cu's as for the pfc this is the prospective fault current i think they require it from phase to earth so ohms law 230/0.17 gives you the current,
Hope this helps
AJ

Many thanks - that's great!
niloc1

If your meter dosn't have a pfc test option just divide your 0.17 into the line voltage to get you pfc in amps then divide this into 1000 for Ka

Thanks darkwood - niloc1

 

[Guest123]

Is PFC not the highest reading of the PEFC and PSCC i.e, L-E and L-N. With L-N nearly always being the higher of the two.

 

[ajelec10]

Just couldn't remember off me head but you sound correct lenny thank you for the clarification
Regards
AJ

 

[Darkwood]

just an addition to your query if your looking for pfc on a three phase system you need to find it from the highest result from the 3 line supplies then double it before you write it down.

 

[Monkey1984]

just an addition to your query if your looking for pfc on a three phase system you need to find it from the highest result from the 3 line supplies then double it before you write it down.

On this point I know you have to double the highest reading on 3 Phase but can't remember why? Can someone enlighten me please???

 

[Darkwood]

On this point I know you have to double the highest reading on 3 Phase but can't remember why? Can someone enlighten me please???

In single phase a short circuit L-N or L-E is 230v where as in three phase you have to consider a short between the phases 400v which will nearly double the fault current and as most meters cant test between phases its easier although crude to just double it.

 

[Monkey1984]

In single phase a short circuit L-N or L-E is 230v where as in three phase you have to consider a short between the phases 400v which will nearly double the fault current

Simple as that eh.