The electrical system where the neutral and earth are connected.

[thaibeachlovers]

I think it is called the MEN system.

 

Can anyone explain how connecting neutral and earth at the consumer unit works, please? Why doesn't the current just go into the earth rod?

I just don't get how it works.

[bankruatsteve]

There's probably better 'splainers around here but here's mine...

 

MEN uses multiple points on the distribution line to bond N to E.  The CU is an additional and important part of that.  N to E bond will keep any E potential low and divert any faults back through the N.  Current won't go to ground because there is no reason to - it want's to return to home (so to speak).

[Crossy]

The whole point of using TNC-S is to provide a metallic (low resitance) path from your earthed metalwork back to the star-point of the transformer. This means that any L-E fault will create enough current to operate the circuit protection (MCB).

 

In the past the system actually provided a separate ground connection back to the star point as TNS.

 

Without that metallic connection you are reliant on the resistance via your rod which could be several hundred ohms. Hence the need for a protective device that operates at a much lower current (your RCD/RCBO).

 

Having lots of N earthing points (MEN) reduces the risk imposed by a broken neutral.

 

Detailed discussion, diagrams etc. in the Wiki here https://en.wikipedia.org/wiki/Earthing_system

[SomchaiDIY]

1 hour ago, thaibeachlovers said:

Why doesn't the current just go into the earth rod?

Your idea about current in ground rod is true

 

Some small current can pass at the ground rod

 

For normal operations current makes route of less resistance on neutral line

 

Many neutral to ground connection on line help with safety level for this type system 

 

[thaibeachlovers]

Thanks for the replies. I learned that the path is easier via the neutral line than the earth rod. I thought it was the other way around, so good explanation.

 

I had googled it before asking on here, but didn't find anything I understood.

[bluejets]

In addition, the purpose of the main earthing electrode in the M.E.N. system is to minimise the possibility of the supply voltage floating above ground.

Sometimes, well most times, a difficult concept for the lay person to comprehend.