11.5ka?

[marksparky]

hi folks am i missing something here on a tt system ze is 19.9ohms and supply obv 230v giving a pfc of 11.5ka so if the mcb type b is rated at 6ka is this a problem? apologies in advance if im bein thick

 

[dufjax]

hi folks am i missing something here on a tt system ze is 19.9ohms and supply obv 230v giving a pfc of 11.5ka so if the mcb type b is rated at 6ka is this a problem? apologies in advance if im bein thick

11.5 amps more like??

0.012ka

If i've done the maths right.... It is off the top of my head so I'll hold my hands up if wrong!

Jim

 

[scotsparky]

If its a tt system that then dont worry to much about the low fault current as RcDS will get it. (maz as for 30ma rcd 1667ohms) Be carefull with your maths wright calculation wrong symbol at en. it can cause a lot of problems and will get failed in exams.

 

[Guest123]

I'd agree with Jim, I wouldn't expect a fault current anywhere near that high on a TT system.

Been testing on TT's all week funnily enough all around 45 - 50ohms Ra and fault currents of 20 - 30A, 0.020 - 0.030KA.

As a side note manufaturers will guarantee their MCB's (6KA ones) installed in consumer units to BS.........(the number fails me at the mo) to a maximum of 16KA.



Edit.....BS 60439-3.

 

[roukel01]

tested a campsite Zs on the furthest Hook Up at 18 Ohms today, probably the lowest I've measured on a TT system.