isolators for earth bar or not?

I suspect they're not so much intended to be electrical isolators, so much as physical stand-offs - to give a bit of a gap behind the bar to make it easier to work (getting fingers around the back of the cables for example). On the other hand it possibly makes testing easier if you can remove parallel paths to the chassis easily.

   - Andy.

Thanks for reply. No, they actually do the job of electrical separators as well not only being a spacers.

We also use these bobbins/isolators for perimeter earth but it has a reason to test Zs loop impedance but why do they used in regular control panels...same reason? Don't thinks so.

I have seen it in the UK for systems with clear/dirty earth segregation. I suspect it is one of those things that is left in as it does no harm, and if you do need it, then it is already there. Saves stocking two sorts of spacer and a small risk of fitting the wrong one.. Then there are odd test and fault situations where you may prefer not to divert large currents through the box.
In those parts of the world that do permit customer side N-E links, it is often done with bars on posts this way to allow the electrode  linking to be tested in isolation of the supply N - which might confuse tests of the electrodes with current going into the electrodes next door.
Mike

I have seen it in the UK for systems with clear/dirty earth segregation. I suspect it is one of those things that is left in as it does no harm, and if you do need it, then it is already there. Saves stocking two sorts of spacer and a small risk of fitting the wrong one.. Then there are odd test and fault situations where you may prefer not to divert large currents through the box.
In those parts of the world that do permit customer side N-E links, it is often done with bars on posts this way to allow the electrode  linking to be tested in isolation of the supply N - which might confuse tests of the electrodes with current going into the electrodes next door.
Mike