230v between N+E and 0v between L+E

[An Buachaillín Bán]

Hi all,

I was called out earlier today to a house where a plumber was fitting a new mains electrics shower. He wanted to know if the existing cable was of a suitable size. I am a recently registered electrical contactor, however I hadn't come across this issue before. The cable was a 6sq pvc pvc. Houses were built in the 70s but cable wasn't as old, as they were brown blue and earth. However, I'm getting 230v across N+E, and 0v across L+E. Would I be right in assuming the house may not be neutralised?

Thanks in advance for all advice

 

[nicebutdim]

@Risteard or @LastManOnline might be best placed to answer questions pertaining to Irish regulations.

 

[pc1966]

It sounds more like reversed polarity which is very dangerous as (I think) ROI is like UK in that it has OCPD only in the L path and so if L & N are swapped you have no protection against faults to E.

AFIK the "neutralised" aspect is basically a local earth rod on the TN-C-S supply but @Risteard or @LastManOnline are the best to advise.

It could be a floating CPC leaking to L, but it is something you have to get professionally checked AS SOON AS POSSIBLE!

 

[An Buachaillín Bán]

Hi all,

I was called out earlier today to a house where a plumber was fitting a new mains electrics shower. He wanted to know if the existing cable was of a suitable size. I am a recently registered electrical contactor, however I hadn't come across this issue before. The cable was a 6sq pvc pvc. Houses were built in the 70s but cable wasn't as old, as they were brown blue and earth. However, I'm getting 230v across N+E, and 0v across L+E. Would I be right in assuming the house may not be neutralised?

Thanks in advance for all advice

Apologies, I edited the previous post. I'm getting 230v across L+N and 230v across N+E. But 0v across L+E

 

[James]

The N is definitely missing.

0v from L to N means that there is a connection between the 2
but because N to E is at 230v it means that you must have a floating N

Edit,
after reading the last post, it may well be that you have a reversed polarity fault.
some proper investigation needs to be done with the house isolated from supply until you can be sure that the polarity and earth are ing god working order and the correct way round.

 

[pc1966]

Apologies, I edited the previous post. I'm getting 230v across L+N and 230v across N+E. But 0v across L+E

That is a prefect fit for reversed polarity.

It might be something slightly less serious, but until found and fixed should be treated as a very serious fault.

 

[timhoward]

Also please don't assume its safe to grab hold of the consumer unit cover and pull it off, if it's a metal CU.

 

[Risteard]

As above, it sounds like reverse polarity to me.

 

[nicebutdim]

It sounds more like reversed polarity which is very dangerous as (I think) ROI is like UK in that it has OCPD only in the L path and so if L & N are swapped you have no protection against faults to E.

AFIK the "neutralised" aspect is basically a local earth rod on the TN-C-S supply but @Risteard or @LastManOnline are the best to advise.

It could be a floating CPC leaking to L, but it is something you have to get professionally checked AS SOON AS POSSIBLE!

Caught mention of 'neutralised' and completely missed the fact that 230V was present between N&E.

 

[Lucien Nunes]

As above, but repeated to reinforce the message: If the polarity is reversed at the supply terminals or meter, no single-pole fuse or circuit breaker will offer any protection whatsoever against earth faults, and all circuits will be effectively fused at whatever the main fuse rating is. You might have 100A fusing on every single appliance and any minor fault could turn into a fireball. Hopefully it's only on that one circuit but it needs checking immediately.