What is the exact function of this device connected between ground and neutral?

Question

This is the photo of the power distribution panel inside industrial building. On the left most, next to the two thick wires colored yellow/green so as it is likely to be the "ground" we see a strange looking device connected between the two copper rods. There are two more blue wires more on the right. Deciding from color and letter N, the blue wires are connected to the horizontal rod that is "neutral".

Hence deciding from labeling and cables, the device seems connecting neutral and ground in the distribution box that I would expect to be directly connected here. However the device appears more complex than just a simple rod. Why does it appear more mechanically complex? I assume the complexity is somehow related to its less than trivial electric functionality.

Answer 1

Looking at the object close up reveals what looks like two parts. The first, on top, is a simple shorting bar. This is a hunk of copper designed to be easily connected or disconnected from its place between two screws--loosen the screws and slide the bar down and they're disconnected. This one appears to be stamped with a rating, 600 A.

These are very common to see on lab power supplies, to connect one side of the supply to ground without needing to use a cable. This one is much more heavy-duty than those, though--it would have to be, since it's apparently rated for 600 amps!

The second part is harder to see. Underneath the shorting bar there appears to be another metal element, though this one is a different color (perhaps a different metal, or plated) and (to my eye, at least) appears thinner. This could be one of two things:

• It may be completely electrically isolated, purely there to hold the other ends in place. In this case, disconnecting the shorting bar would disconnect neutral from PEN--why you might want to do that, I'm not sure, but there may be some reason.

• Or, it may be a high-current shunt resistor--a large version of one of this type of metal-element current shunt. In this case, disconnecting the shorting bar would allow one to measure the current passing through it, while connecting it would bypass the current shunt, preventing it from wasting power.

Answer 2

On the left most, next to the two thick wires colored yellow/green so as it is likely to be the "ground"...

The two thick wires are connected to PEN (protected earth and neutral) as opposed to protective earth (PE). Ground is such an ambiguous term to [people from the UK (as I am) so I suspect you might be from north America where it's quite common to refer to ground when you would mean earth in other parts of the world.

Anyway, the clue is in your picture here: -

Hence deciding from labeling and cables, the device seems connecting neutral and ground in the distribution box

It's connecting neutral and PEN

Why does it appear more mechanically complex? I assume the complexity is somehow related to its less than trivial electric functionality.

It looks like a link to me: -

Answer 3

This is a simple neutral disconnect block like this one.

source : https://www.pes-group.co.uk/media/parkuk%20cms/datasheets/woehner/1326%20-%20WOEHNER%20Part%20Number%2003213.pdf

In industry, the earthing/grounding system may be different from the home earthing/grounding system. This neutral disconnect block makes it easy to change TN to IT earthing/grounding system for example. See https://en.wikipedia.org/wiki/Earthing_system

Answer 4

The picture is from this Wikipedia article (among others). The caption under the picture is correct. It is a shorting bar that connects the neutral and earth. The nearby label “PEN” stands for Protective Earthed Neutral.