Concrete lighting column

[streetlighter]

Just to settle a debate from work today. There are plenty of old concrete lighting columns still in service all of them have a metal access door to gain access to the service cutout and control gear if fitted to the base.
Our client spec says we do not earth the door but to comply with the regs should this door need to be earthed ?

 

[Spark123]

I doubt there is any chance that the access panel door can become live under fault conditions so I wouldn't be to bothered about earthing it.

 

[RF Lighting]

I don't see any reason why it would need earthing. It doesn't directly form part of the electrical installation IMO.

Are street lighting installations carried out to BS7671, or is there a different standard specific to this sort of installation?

 

[streetlighter]

Theres not much about highway lighting power supplys in BS7671 but we do follow the regulations. The local authoritys have some of there own "rules" about the way the columns have to be wired internally and the minimum cable sizes for there private supply networks.
I thought as much with regard to the need to earth the metal door on a concrete column, bit like bonding a metal radiator fed via plastic pipe.

 

[ColJack]

I've seen one where the board has rotted and fallen off the inside of the pole, and fell onto the door.. but it was still electrically sound so no fault..

earthing it makes no odds anyway, the feeds aren't fused as far as I know.. it would only be of any use if the fault happened after the fuse in the post..

 

[RF Lighting]

They must be fused somewhere along the way. AFAIK, they are either just tapped of the same ring main which supplies the houses in the street, or have a dedicated ring from the substation.

 

[Spark123]

There is usually a cutout in the bottom of the lamp post, but as coljack says it isn't much use if the fault is before this.
The feed could be fused up in the 100s of amps back at the sub or in a fuse box in the street.

 

[ColJack]

my cousin dug one up with a JCB once and said he tried to short it out for safety ( rather than having a sparking live cable in a hole in the footpath ), but no matter how many times he dropped the bucket on the live ends it just kept sparking..

 

[1john]

now i wish i was there to see that

 

[greeny4]

this is true, street lights with electricity board feeds are fused in the cut-out with a 6-32 amp fuse. If a damage occurs on the service before the cut-out, very rarely will it trip the fuse at the sub unless there is a mains fault. Service faults usually keep popping untill they burn back.

 

[securespark]

Are street lighting installations carried out to BS7671, or is there a different standard specific to this sort of installation?

110.1 Regs apply to:

(x) external lighting

(xiv) highway equipment and street furniture

So I guess they would be to 7671.