OT: Neutral Connection in EU Countries

kamenges · Apr 17, 2019

If I have a 5-wire 3-phase supply to an enclosure does the neutral connection point have to be insulated and touch safe? I know it will need to be isolated from ground but does it have to be covered? I would think so since a loss of the neutral connection from the supply could potentially put the neutral connection point in the panel at the voltage level of the incoming 3-phase conductors. I would just like clarification on that.

Thanks,
Keith

lfe · Apr 17, 2019

If the neutral is lost form the supply then it's a serious risk since the larger load connected to that neutral will attract the neutral to that phase and put the rest of the loads connected to other phases at a much higher voltage. it's something that better never happens. I've seen fried equipment for that reason

And that larger load can be outside your cabinet, anywhere on the plant.

This is a reason for not use the supply neutral and better to put a 400/230V transformer, then you can make your own common/neutral connecting one side of the secondary to ground.

If you use the supply neutral then connections should be touch safe, if you do your own common/neutral connected at one point to ground with a transformer then connections can be nude

jraef · Apr 17, 2019

It's simpler than that. A "neutral" is always considered a "current carrying conductor" and as such must always be insulated.

kamenges · Apr 17, 2019

I agree that the conductor needs to be insulated but what about the connection/distribution point? If you look at the breaker box in your house the neutral will be connected to something that looks startlingly like a ground bar. So does this neutral distribution point need to be touch safe, specifically in an EU member state?

Originally posted by lfe:

This is a reason for not use the supply neutral and better to put a 400/230V transformer, then you can make your own common/neutral connecting one side of the secondary to ground.

I would tend to agree with this. in this case we allowed our customer to choose their 230V supply arrangement and they chose to use the line to neutral method.

Keith

bkottaras · Apr 17, 2019

kamenges said:
I agree that the conductor needs to be insulated but what about the connection/distribution point? If you look at the breaker box in your house the neutral will be connected to something that looks startlingly like a ground bar. So does this neutral distribution point need to be touch safe, specifically in an EU member state?

I would tend to agree with this. in this case we allowed our customer to choose their 230V supply arrangement and they chose to use the line to neutral method.

Keith

Keith,

I assume this is the same project with the Ropex heating system.
Use 5 Ferraz Shawmut FSPDB2A distribution blocks inside the main panel.
The 3ph (3) power carrying conductors land to the breaker, out the breaker to the blocks.
The Neutral and PE land directly to the blocks.

kamenges · Apr 17, 2019

Originally posted by bkottaras:

I assume this is the same project with the Ropex heating system.

You are correct, sir.

Originally posted by bkottaras:

Use 5 Ferraz Shawmut FSPDB2A distribution blocks inside the main panel.

Interestingly, that is what I have in there now for the neutral. The PE is an actual ground bar. But that really doesn't affect the question. By standard, does the neutral distribution point HAVE TO be touch proof.

Keith

janner_10 · Apr 17, 2019

kamenges said:
By standard, does the neutral distribution point HAVE TO be touch proof.

Keith

Over here, yes. It is classed as a live conductor and should be treated so.

kamenges · Apr 17, 2019

Very good. Thanks for the clarification. That makes sense.

Keith

BobB · Apr 17, 2019

Interesting - neutrals are not covered in Australia - brass link but insulated from the enclosure that is all - the brass link is left uncovered - speaking of a form 1 switch boards here. They are covered domestically.

PLCnovice61 · Apr 17, 2019

In Australia/New Zealand, the neutral "Bar" connection isn't covered and can be touched at anytime without any consequences, but don't of course get between a neutral wire and the "Bar" or you will get a nasty/fatal shock and the earth leakage protection of course wont see it, so won't trip.
Of course we aren't in the EU, but nor will janner_10 be shortly.

g.mccormick · Apr 17, 2019

kamenges said:
I agree that the conductor needs to be insulated but what about the connection/distribution point? If you look at the breaker box in your house the neutral will be connected to something that looks startlingly like a ground bar. So does this neutral distribution point need to be touch safe, specifically in an EU member state?

I would tend to agree with this. in this case we allowed our customer to choose their 230V supply arrangement and they chose to use the line to neutral method.

Keith

The breaker box in your home, the neutral is behind the panel. You have to take the panel apart to get to it, if you take the panel apart, the live bus bars are also exposed. So at that point, nothing is touch safe. When the panel is assembled in the normal sense, the neutral bus is safely behind the cover.

LadderLogic · Apr 17, 2019

I always treat neutral as something that MAY BE grounded, although in most cases it is. That differs from PE that is assumed to be ALWAYS grounded.

lfe · Apr 17, 2019

kamenges said:
I agree that the conductor needs to be insulated but what about the connection/distribution point? If you look at the breaker box in your house the neutral will be connected to something that looks startlingly like a ground bar. So does this neutral distribution point need to be touch safe, specifically in an EU member state?

Keith

For distribution cabinets do not apply the same standards as for control cabinets. They do not usually have hinged door, you need tools to open them or they are even sealed or locked

For control cabinets the supply neutral need to be touch safe

kamenges · Apr 17, 2019

Originally posted by LadderLogic:

I always treat neutral as something that MAY BE grounded, ...

Do you mean by design or by construction? As far as I know one of the things that makes a neutral a neutral is that it is at ground potential. If it isn't at ground potential it would be an ungrounded common.

Granted, the neutral conductors could potentially not be at ground potential due to failure or incorrect installation. That would be a problem.

Keith

g.mccormick · Apr 17, 2019

kamenges said:
Do you mean by design or by construction? As far as I know one of the things that makes a neutral a neutral is that it is at ground potential. If it isn't at ground potential it would be an ungrounded common.

Granted, the neutral conductors could potentially not be at ground potential due to failure or incorrect installation. That would be a problem.

Keith

There is a distinction...

Normally, the neutral is the "grounded" conductor.

The ground though is the "grounding" conductor.

There is a distinction, and the neutral is not always grounded. Think of a lot of 24VAC transformers in equipment. They are probably not grounded neutrals.

OT: Neutral Connection in EU Countries

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