TT - PME conversion - Maximum EFL value is?

[securespark]

Having just talked about supply types, this has jogged my memory.

I have come across a few TT conversions to PME, where the Ze>0.35, but <0.8.

The DNO reckons this is OK. I reckon whatever the method of supply, if it is PME, it should be 0.35 MAX.

They however, claim that in some cases, it is impossible to bring the EFL down to <0.35 with TT being as it is.

 

[Lectrician]

Our DNO is the same - they will always measure the Ze, but if it is above 0.35, they simply record 0.35.

The blokes on the ground do use 0.8 as the max figure.

Odd aint it?

 

[securespark]

Yeah. 0.8 is the max for TN-S. 0.35 for PME. Why suddenly 0.8 for the both?

I mean, if you get close to that figure (0.8 I mean) for the Ze, the Zs could easily exceed the max (I use 0.85 for 30A 3036 ring main).