hotel Ze 2.8 ohms

[tester11]

started a periodic inspection on a hotel today to find out the Ze was 2.8 ohms which now means that a lot of my Zs values are above what they should be. a PME connection is rquired but if the installation has to be bought up to 17th edition (as it is in domestic situations)before the SSE will provide the connection then the whole hotel would require total upgrading at major costs. has anyone come across anything like this before ??

 

[telectrix]

what is the earthing system now?

 

[i=p/u]

rcbo th circuits

 

[Sintra]

Is it a TT at the minute?

 

[topquark]

If it's a TN system then the DNO will need to sort it.

 

[tester11]

Its cable with an outersheath which is a material wrapped round. then stripped back before cut out and earth clamp onto inner sheath. very old cutout also

 

[tester11]

only started the day but am guessing theres a lot of circuits to fit rcbos to, and a lot of rewirable boards where rcbos cant be fitted.

 

[i=p/u]

tn-c-s then

 

[topquark]

Sounds like it's a TNS system then.

 

[tester11]

yeh it is tns.

 

[topquark]

DNO's problem then IMHO. Is the clamp in reasonable condition as far as you can tell? Worth getting them to have a look at upgrading the tails as well (if necessary).

Is it single or three phase supply?

It won't necessarily need to be brought entirely up to 17th. Depending on the state of the wiring and what additional work is being asked for/necsessary as a result of the PIR.

 

[nickblake]

Firstly when testing realy you should test the supply parameters first IE: the Ze test , reason for this is this will ensure the supply complies with the readings set out in the regs also the Zs results as you have found out also when you have done the R1R2 tests it gives you an idea of what results you should expect Ze + R1R2 = Zs

As for the earthing arrangements what you have describled does sound like a TNS system but it could well be a TT , i have come across this on occasions where the outer sheath has been connected but have later found out that the sheath has not been connected in the main junction underground

 

[Octopus]

I tested a TN-S system today and got a value of 5.85 ohms - the reason, no bonding connection between the CU and the main connection point provided by the DNO.

Seems it may have been like this since 1966 when the house was built!

 

[tester11]

yeah ur right i usually do the ze and pfc tests first but couldnt shut hotel down when i arrived.

 

[tester11]

looks like al need to contact SSE and find out what they say bout it then. cheers folks