PE Busbar installation

[Designmen90]

Hello guys,
here I have one interesting picture from site. I saw one DB so I opened the door. What I see just confused me. The pictures are attached. If you take a closer look, you will see that this busbar is installed on few nuts. Is this allowed?

Anyway, if there is situation where busbar should not be isolated from mounting plate, how in such situation determine the size of bolts for connecting busbar and mounting plate directly. Should it be M6, M8...probably it depends on the size of busbar, but how to determine bolts size..

 

[Strima]

The earth bar is bolted direct to the metal enclosure as there's no need for separation. The enclosure would be tied to earth anyway so why isolate it and then have a fly lead connecting them together?

You may rarely get an isolated earth bar if there's earth monitoring in place such as an IT system but then there shouldn't be easy access to them anyway.

 

[Steviec1]

The earth bar is bolted direct to the metal enclosure as there's no need for separation. The enclosure would be tied to earth anyway so why isolate it and then have a fly lead connecting them together?

You may rarely get an isolated earth bar if there's earth monitoring in place such as an IT system but then there shouldn't be easy access to them anyway.

In some panels there can be 2earths, one is PE and will be bolted or connected by cable to the metal backplate, the other will be a "clean earth" this will not be connected to earth but will be used to link screens from processing cables e. g 4-20mA to a common point.

 

[Designmen90]

he earth bar is bolted direct to the metal enclosure

...and this way with few nuts is OK?

 

[Strima]

...and this way with few nuts is OK?

It doesn't need a lot of mechanical strength as it's not load bearing. Just a sound electrical connection and strong enough to withstand someone hanging off a spanner tightening the nuts up.