Can MEN link share terminals?

Post Reply
Dan L
Posts: 158
Joined: Tue May 19, 2020 10:00 pm
Answers: 0
Has thanked: 4 times
Been thanked: 3 times

Can MEN link share terminals?

Post by Dan L »

On a commercial switchboard the MEN link (which was connected by lug not a screw type) was bolted onto the same stud as as another conductor on the earth and neutral connection.

The other conductors where extensions to a second earth and neutral bar of the the same enclosure.

To me this seemed wrong, bad practise and inconvenient if anything.

I can only find ref 2.9.4.3

provided with a separate terminal for—
(i) the incoming neutral conductor terminating at the switchboard;
and
(ii) the neutral conductor(s) associated with each outgoing circuit
originating at the switchboard.

(not sure if the conductors used for extended to another bar counts)

And possibly 5.3.5.1
Which may suggest a dedicated earthing terminal is required on the neutral bar.

Any other ref I'm missing is this compliant or not?

I tried to upload publics hopefully it worked


Image
Attachments
IMG_20201201_121122.jpg
IMG_20201201_121126.jpg
IMG_20201201_121128.jpg
AlecK
Posts: 912
Joined: Thu Apr 16, 2020 11:24 am
Answers: 5
Has thanked: 2 times
Been thanked: 351 times

Re: Can MEN link share terminals?

Post by AlecK »

Not very good practice; but I believe 'compliant'.

In 2018 edition, 5.3.5.1 is amended to require that the MEN must be "located in an accessible position for disconnection and testing purposes".
Which emphasises the fact that we have to be able to remove the MEN easily.

The links between sections of busbar are effectively part of the bar.
They should be connected such that they don't get removed / disconnected / loosened when the MEN link is removed.
So if they are 1st on stud, secured by a nut, and therefore remain firmly connected when link is removed from above the nuts, then no problem.

But this case appear to just have the one nut per stud, so anything connected to 2nd set of bars risks being disconnected by removal of link.
Even worse; looks like the lugs for the linking conductors are over the top of the MEN.
Very poor practice; and defeats the point of having a removable MEN.
But not actually in breach of any clause.
AlecK
Posts: 912
Joined: Thu Apr 16, 2020 11:24 am
Answers: 5
Has thanked: 2 times
Been thanked: 351 times

Re: Can MEN link share terminals?

Post by AlecK »

There's also 2.9.5.34; which requires the terminals for the MEN to be "legibly and indelibly marked"
Since the MEN is NOT at one extremity if the bar, and the main N is not immediately next to it; the Exception can't apply.
I can't see the required marking, so non-compliant in that regard.
Dan L
Posts: 158
Joined: Tue May 19, 2020 10:00 pm
Answers: 0
Has thanked: 4 times
Been thanked: 3 times

Re: Can MEN link share terminals?

Post by Dan L »

Thanks I really appreciate the feedback.
Post Reply