No. The box is better remaining isolated.
Outside Metal Enclosure Bonding.
- Thread starter OuterSpaceHopper
- Start date
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Lamp post are ( as far as I recall ) bonded to the Ground. I can check this at the week end as I will be arranging the power to the village Christmas Tree lights from an existing take off in a lamp post. The take off was installed by council electricians many years ago and was updated for this years lights.
What has that got to do with it?
In your opinion - and, for what it's worth, my opinion is the same. However, I'm not sufficiently arrogant to feel that other opinions are inevitably invalid.
Kind Regards, John
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It's not arrogant. It's the correct information.
Your ultra-polite, ultra-understanding and ultra-tolerant disposition is not always the best way.
Sometimes mediation is not required. Sometimes it is right and wrong.
Some people believe the world is flat. It is not.
Your ultra-polite, ultra-understanding and ultra-tolerant disposition is not always the best way.
Sometimes mediation is not required. Sometimes it is right and wrong.
Some people believe the world is flat. It is not.
Maybe not, but it's an honest expression of my views - which I've already described.
Consider the infamous 'isolated metal bath' discussion. The pros/cons of earthing it depend upon a judgement as to which of two scenarios (both extremely rare) is the more likely - and there are people who genuinely differ in opinions as to which is the more likely. You may say that the judgement of one of those groups is 'incorrect', but I wouldn't presume to say that.
Kind Regards, John
A lamp post is a tall skinny outside metal box with electrical equipment inside it.
Yes, but is the "electrical equipment inside it" itself already fully/adequately insulated (as would be the case with an IP-rated socket)? If there are any non-insulated (or inadequately insulated) electrical parts/connections within the lamp post, that would obviously be a totally different situation, requiring earthing of the post (if metal!).
...and it would be better if it were totally isolated.
... unless, as I've just written, it contains uninsulated (or inadequately insulated) live parts.
Kind Regards, John
No. It WOULD be better IF it WERE totally isolated like the OP's box.
In the base there is a small plastic cut out with DNO conductors from the street into the bottom glands. It is fitted with a 3 amp fuse. From the top of the cut out Live and Neutral go up the column to the timer / daylight sensor / lamp at the top of the post. I do not recall seeing an earth conductor at the cut out Neutral block. Three earth leads are bolted to a termainl welded to the inside of the post, one comes up from the bottom of the hollow below ground, one appears to go up the column and the third to the SWA of the cable that takes power to the Christmas lights socket.
From a county council document
23.1 The whole of the installation shall be earthed in accordance with the requirements of the current BS 7671, IEE Wiring Regulations, and with the recommendations contained in BS 7430, Earthing. Earthing shall be carried out in PVC insulated copper cable green/yellow in colour. All metallic parts of the ancillary equipment, column, lantern and gear shall be bonded together to form a continuous earth path to the earth stud of the column.
6. Earth Electrode Resistance – tested in accordance with BS 7430 and BS 7671.
That quoted not all columns have RCD protection. This seems to depend on whether the supply is direct from the street distribution cable or from a cable specific for street lighting with RCD protection in a central cabinet feeding several loghting columns
From a county council document
23.1 The whole of the installation shall be earthed in accordance with the requirements of the current BS 7671, IEE Wiring Regulations, and with the recommendations contained in BS 7430, Earthing. Earthing shall be carried out in PVC insulated copper cable green/yellow in colour. All metallic parts of the ancillary equipment, column, lantern and gear shall be bonded together to form a continuous earth path to the earth stud of the column.
6. Earth Electrode Resistance – tested in accordance with BS 7430 and BS 7671.
That quoted not all columns have RCD protection. This seems to depend on whether the supply is direct from the street distribution cable or from a cable specific for street lighting with RCD protection in a central cabinet feeding several loghting columns
Which many do, and they get demolished by badly driven cars and in some cases the "fuse" is the 25 mm² cable melting what ever it comes into contact with. The emergency services do get a bit pi***d if the crumpled metal is Live.
I don't understand. The OP's box contains something which is already adequately insulated - so, in that case, I completely agree with you. However, if a metal 'enclosure' (be it the OP's box, a lamp post or anything else) contained exposed (or inadequately insulated) live parts, then it would be both necessary and required that the metal enclosure be earthed, wouldn't it?
That's why I asked bernard what was inside the lamp post - because it could be a different situation from the OP's box.
Kind Regards, John
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.
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