Eicr Problem

[markyspark76]

I've been testing a army accommodation block I have 8 x Merlin gerin fuse boards which have two supply's effectively two dis boards in one metal enclosure 16dbs in total they have two main switches double pole supply cable to boards is two core 16 mm swa incomer is 120mm 4core armour no surface head fuse and historical the earthing system is TN-S the situation is if I isolate both switches to db A and B I have 240volts from live side of main switch to neutral bar on db A and db B if I remove both neutrals from their switches and measure voltage from live of switches and both neutral bar I've still got 240 volts I have had this on every fuse board in the building my thinking is borrowed neutrals through out neutrals and earths connected some where or the supply is Pme any ideas both supply's in db are on same phases

 

[markyspark76]

DB A and B both isolated by main switch remove neutral from main switches put one probe on incoming live conductor in main switch and other probe on neutral bar of A or B there is then no return path for the neutral as DP main switch is isolate but still getting 240 volts live to neutral

 

[samson337]

So it's tncs or pme where's the prob

 

[steptoe]

are the main switches actually opening?

are you getting voltage L-N or N-L ?

 

[markyspark76]

The earthing system is tn-s if the neutral is removed from main switch I get 240volts from live of main switch and neutral bar

 

[steptoe]

The earthing system is tn-s if the neutral is removed from main switch I get 240volts from live of main switch and neutral bar

I'll aslk it again,

is it 230v

L-N

or

N-L

??????

this is VERY important,

also,

is the main switch actually opening? have you proved this?

very basic test, but, VERY important to actually prove,

removing the NEUTRAL is VERY VERY dangerous without proving this other stuff first.

 

[Sidewinder]

Any RCD's?

 

[markyspark76]

All switches are closed and neutral conductor is removed from switch if I measure live of db A to neutral of db a =240 volts if I measur live of db a to neutral bar if db b I get 240volts both fuse boards are in same enclosure

 

[Sidewinder]

If your switches are closed then you will get the results you describe, as the switches will be conducting.

 

[markyspark76]

No RCD

 

[Sidewinder]

Quite Canoe!

 

[markyspark76]

Sorry switches to DB's closed testing L-N 240volts

 

[steptoe]

:shakehead

 the swithches need to be open,

and you need to prove they are open, not simply rely on the physical position of the switches,

headbang

have you any idea how dangerous it is to remove a neutral on an energised installation!!!!!!!!  

 

[markyspark76]

Yes I do no how dangerous it is the board was isolated at the sub prior to neutrals removed

 

[steptoe]

obviously NOT isolated, if you are getting 230v at the board,

 

[SLIPSHOD & SLAPDASH]

I think you also need to clarify which switches you are operating. Are these on the boards your testing or remote, at the supply.

 

[Badger]

http://www.tradeskills4u.co.uk/courses/2391-inspection-and-testing maybe this will help the op

:slap

 

[M107]

So if I get this right the incoming swa (a submain?) is glanded to a metal enclosure that in turn houses 2x cu's (also metal clad?).

The swa splits 2x cores to one DP switch for cu 'A'  with another 2 cores going to a second DP switch for cu 'B'.

you are isolating both switches (opening the switch) so turning off all circuits from cu A & B.

You are then removing the neutral from the supply side of the DP switches (bad idea if so).

Then you are putting a probe on the supply (not the load side) Line terminal  of DP switches & other probe on the CU neutral busbar.

Also in the same building you have other cu's & you are wondering if they are connected to the cu's A & B by a borrowed neutral, so giving rise to you being able to measure 230v between the supply line & an isolated cu neutral busbar.

Correct so far?

 

[ACR ELectrical]

I think the OP should start again explaining this, and take careful note of terminology used.

My first point would to prove your actually isolating what you think your isolating, if your isolating the sub-mains have you proven it is correct? Seems like your not performing safe isolation adequately.

Also if you are getting voltage, why are you disconnecting the neutral??? :facepalm:

 

[kme]

As my esteemed colleages have asked:

What are you trying to test for, and why.

From what you`ve said - unless I`m misunderstanding - you have an odd / potentially dangerous method of doing ....whatever it is you`re doing......

More confused.comness