Outside Metal Enclosure Bonding.

[EFLImpudence]

If the lamp post is an exposed-conductive-part then it is NOT totally isolated but It WOULD be better IF it WERE.

Look, I think it is agreed (apart from Bernard who thinks everything is) that the OP's box is NOT an exposed-conductive-part therefore earthing is not required.

The other option is, is it an extraneous-conductive-part which requires bonding? The answer is NO, it is outside therefore there are no exposed-conductive-parts of the installation which are simultaneously accessible.

The best advice is to ensure that the box remains isolated.

I am surprised no one has suggested TTing the socket. That doesn't mean I think it should be.

 

[JohnW2]

I have occasionally looked inside street cabinets, and they always seemed to have an earth stud on the root (which is buried in the ground, and the cabinet bolted to it), and one each opening door so they have a G&Y link to bond the doors to the cabinet.

That sounds fair enough. As I've been saying, if there are exposed (or inadequately insulated) live parts within a metal lamp post, cabinet or whatever or if (as bernard has indicated), it is considered possible that normally-insulated live parts could become exposed as a consequence of the structure being damaged (e.g. by impact from a vehicle), then it would seem essential that the metal 'enclosure' should be earthed.

However, this is very different from the OP's situation, in which what is inside the metal box is fully insulated and very unlikely to be destroyed by impact etc.

Kind Regards, John

 

[JohnW2]

Look, I think it is agreed (apart from Bernard who thinks everything is) that the OP's box is NOT an exposed-conductive-part therefore earthing is not required.

You and I are certainly agreed, and I imagine that most other people would also agree, even if not bernard.

However, that is because of what is inside the OP's box, which means that the box is not an exposed-c-p. The situation could well be very different for a lamp post, street cabinet or whatever, with the casing being an exposed-c-p. Bernard also makes a valid point about the possibility of trauma exposing live parts which were normally adequately insulated - but, again, that is (presumably!) not relevant to the OP's box.

Kind Regards, John

 

[EFLImpudence]

I am not disputing that the lamp post IS an exposed-c-p.

I am just saying it would be better if it were not and could be isolated.

 

[JohnW2]

I am not disputing that the lamp post IS an exposed-c-p. I am just saying it would be better if it were not and could be isolated.

I'm not sure that would necessarily be practical - it certainly would not be possible to guarantee that normally well-isolated parts within couldn't become 'exposed' (hence rendering the post an 'exposed-c-p) in the event of vehicle trauma.

It's also very different from what we normally discuss. Within a building, we are agreed that the less ('unnecesarily') earthed metal around, the better - since any unnecessarily earthed metal increases some potential hazards. It's far less of an issue 'outdoors', where earthed things are already all around (and 'live' things shouldn't exist).

Kind Regards, John

 

[EFLImpudence]

No, I know it's not practical. I am just saying it would be better if it were - like the OP's box is.

The same as if I said "It would be better if there were no more wars". Indisputable but ...

 

[EFLImpudence]

So, comparing the OP's box to a lamp post is pointless.

 

[JohnW2]

No, I know it's not practical. I am just saying it would be better if it were - like the OP's box is.

Fair enough - but, as I just wrote, even if it were practical to have an isolated lamp post, I don't think the argument that it would be better not to earth would be particularly compelling, given that it is outdoors. Can you think of any (realistic!) situation in which earthing it would represent a hazard??

Kind Regards, John

 

[JohnW2]

So, comparing the OP's box to a lamp post is pointless.

Essentially true (and it wasn't me who brought lamp posts into this discussion).

However, what I've just written about lamp posts is really equally applicable to the OPs box. Contrary to the situation if the box were indoors (when we're agreed that unnecessarily earthing it would increase hazards), I don't really think that any significant problem arises from (unnecessarily) earthing a metal box which is outdoors. Let's face it, an awful lot of metal objects outdoors have some sort of path to earth.

Kind Regards, John

 

[John D v2.0]

While you lot are discussing lamp posts, I think more people have been hit by cars directly than injured by electric shocks from metal objects!
At least this is a topic everyone can get invoked with
PS personally I think any metal object larger than 1m in any direction should have insulated joints in.

 

[JohnW2]

While you lot are discussing lamp posts, I think more people have been hit by cars directly than injured by electric shocks from metal objects!

I'm sure that's true.

However, I suspect that at least some of the 'electrics' in lamp posts may not be very (if at all) insulated - in which case, even if one forgets possible impacts, there would presumably be no less need to earth it than is the case with any 'Class I' item? Whilst I agree that the risk is very small, if one was going to argue that such a lamp post did not really need earthing, one could use the same argument for any Class I item of equipment - but I don't think any of us would be happy not earthing the exposed-c-p of such an item.

Kind Regards, John

 

[John D v2.0]

OK better idea - supply street lights with an elv supply either in the ground or separately

 

[JohnW2]

OK better idea - supply street lights with an elv supply either in the ground or separately

You could say the same of any LV Class I item!

Kind Regards, John

 

[John D v2.0]

Not quite, I think you'd struggle with your oven/washing machine if you were aiming for better safety.
But street lights use hardly any power and for that matter most of them are electronic nowadays anyway.

 

[JohnW2]

Not quite, I think you'd struggle with your oven/washing machine if you were aiming for better safety.

One certainly might struggle with the conductor sizes need to run an oven or washing machine with ELV - but, if one was "aiming for better safety", I suppose that would have been achieved (with or without earthing of the item).

Kind Regards, John