PME & Broken neutral

[Knobhead]

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I know some countries use protection to guard against a broken neutral in PME systems.
Anyone know how they work?

 

[snowhead]

There was a post recently on here where someone posted a drawing showing it.

RCD before the N to E connection??

 

[Knobhead]

I thought along those lines but it’s prone to imported faults

 

[Edd]

I know some countries use protection to guard against a broken neutral in PME systems.
Anyone know how they work?

Acording to E54 it never happens, so why bother.

 

[Knobhead]

It happened to my house years back.

 

[Edd]

seen it 3-4 times now, last time it had taken out the flexy hoses under the kitchen sink, when they turned the shower on! scarry stuff. but hey they had a good Ze

As snowhead says wonder why they dont fit a 100A 500ma RCD before the NE join.

 

[plugsandsparks]

Doesn't the white wire on the RCD help with this?

 

[Jimmy Boy]

Speak to the DNO ask them if you can fit an Earth Rod as a back up they will probably say no but do it anyway lol
J

 

[Sintra]

Speak to the DNO ask them if you can fit an Earth Rod as a back up they will probably say no but do it anyway lol
J

That is the way it is done in some countries an external electrode is connected to the N / E juncture within the service head.

 

[plugsandsparks]

Just checked the schneider site and they do an under-voltage module for their C60 din stuff, that may do it

 

[somersetsparks]

That is the way it is done in some countries an external electrode is connected to the N / E juncture within the service head.

Most of the underground PME joints to supply buildings are staked by the dno

 

[Jimmy Boy]

That is the way it is done in some countries an external electrode is connected to the N / E juncture within the service head.

As the N/E are shared at the head can you see any problem with taking a rod from MET ? I am struggling to find a reason how this wouldn't improve the safety of the installation if you lost the Neutral
J

 

[MarkieSparkie]

Link to the thread Snowhead referred to earlier, Tony:
http://www.electriciansforums.net/electrical-forum-general-electrical-forum/60473-protection-against-lost-neutral-tn-c-s.html

 

[Jimmy Boy]

I don't quite get where he's saying it should be positioned in relation to it's effectiveness ? My CU has a 30mA non delayed RCD as a main switch will it trip out if the N drops out ? it's the same as his diagram isn't it ?
J

 

[snowhead]

I don't quite get where he's saying it should be positioned in relation to it's effectiveness ? My CU has a 30mA non delayed RCD as a main switch will it trip out if the N drops out ? it's the same as his diagram isn't it ?
J

This is looking at loosing the incoming neutral, before the Neutral / Earth connection, the normal C.U RCD can't detect that.
Current flow thro' the C.U rcd won't be any different.
The Green / Yellow ("Earth") now becomes a return waiting for someone to complete the path.