3ph help and then some!

[mainline]

It's a bold move posting that picture, I'm sure the SY police will be along shortly

SY who said sy !!!

 

[Initforthemoney]

Sooo, thought i would give you guys a bit of an update.

All connected but the EL is too high at the DB (0.8 ish) and should be 0.51 for an 80A so i am going back to install and earth rod which should bring it down a fair bit.

I hope!

 

[davesparks]

Sooo, thought i would give you guys a bit of an update.

All connected but the EL is too high at the DB (0.8 ish) and should be 0.51 for an 80A so i am going back to install and earth rod which should bring it down a fair bit.

I hope!

Where are you going to connect an earth rod?

What is the Ze?

What was the predicted Zs from your cable size calculations? If your Zs is higher than the design value then there is a problem that needs to be investigated.

 

[Initforthemoney]

Ok so went back today and took another Ze reading over the three phases ( i couldnt do it yesterday for various reasons) and they all came back at 0.6 ish but when I tested earlier in the year it was at around 0.10 so didn’t really worry too much at that point.

Thing is, this is on a docks and this supply is metered remotely and all there is is a three phase cut out with the cpc connected to the pme terminal, so somewhere along the line they have altered something to affect the readings. Having said that, there are a huge amount of new buildings etc going up.

I dont think an earth road at the intake end is going to be that successful in bringing those readings down, so I guess my only option is to install a TD Rcd before the 80a TPN switch fuse to protect the sub main, and rod the workshop end.

The two 32A sockets have built in RCD protection, and so does the car charger so i don't think i need to RCD those circuits?

Unless there are any other suggestions?

This is the exact reason i didnt want to get involved in the first place!

Thanks guys.

 

[davesparks]

I dont think an earth road at the intake end is going to be that successful in bringing those readings down, so I guess my only option is to install a TD Rcd before the 80a TPN switch fuse to protect the sub main, and rod the workshop end.

That won't solve the problem, you have a TNCS supply with a Ze which has gone out of spec for an unknown reason.

You need to get the DNO or whoever is responsible for the supply involved to fix the problem.