High pscc ????

[sidekick]

Hi All,
Can any body advise why i am getting a reading for PSCC L-N of 10KA ??

 

[Marvo]

What are you testing? More details please.

If you refer to the appropriate tables in the regs for your values is there a large discrepancy with your actual test results?

 

[sidekick]

What are you testing? More details please.

Main incomming tails L-N

 

[thomasn]

what was your Ze?

 

[Richard Burns]

Are you near a sub station, 10kA is quite possible near a large substation.

 

[sidekick]

what was your Ze?

Tested L-PE with result of 0.29ohms and PEFC of 875A

 

[Rockingit]

Assuming that you have a voltage of around 245V, that's roughly a Ze of .025 - unusual but not impossible. Whereabouts are you / site?

 

[sidekick]

Assuming that you have a voltage of around 245V, that's roughly a Ze of .025 - unusual but not impossible. Whereabouts are you / site?

West yorks, semi on private estate on edge of moors, no sub station near by that i'm aware of.

 

[HandySparks]

What instrument are you using?
I ask because I had a Fluke 1652 on long term loan which was fine on L-E PEFC but nearly always gave ">10kA", ie off the scale, for L-N PSCC. My current Fluke 1652C seems to be behaving itself.

Edit:
This was usually on a TN-C-S supply where the two values should be near enough the same.

 

[Marvo]

West yorks, semi on private estate on edge of moors, no sub station near by that i'm aware of.

If you don't know the length of the supply cabling then you can't calculate the PSCC manually so you don't have much choice but to trust your test results. The reading of 10KA doesn't strike me as extraordinary so I wouldn't lose any sleep over it. A private estate will most likely have its own substation in close proximity.

*Edit* Wouldn't a high PSCC on the supply be a DNO problem anyway and not yours?

 

[High Tower]

I have got a Fluke 1653 that does the same on l-n pscc reading too. 10ka

 

[sidekick]

yes also using FLUKE 1653 but first time I've had this reading.
Do I just put it on the cert and forget about it, put the PEFC on the cert and ignore the PSCC or report it??

 

[Richard Burns]

If the supplied distribution board and protection devices are suitable for that level of PSCC then there is no problem. Remembering that the Short circuit capacity of OPD <50A in a CU to BS60439-3 or BS5486-13 with a BS1361 type 2 suppliers fuse can be considered to be 16kA.