In England we require 30ma (RCD) Residual Current Device for outside lighting that could be accessed by the public, I take this to mean all outdoor lighting .

In England we require 30ma (RCD) Residual Current Device for outside lighting that could be accessed by the public, I take this to mean all outdoor lighting .

I'd suggest that's being  little over-enthusiastic. Anything on private property often isn't accessible to the general public (invited guests etc aren't "the public"), section 714 overall doesn't apply to lights fixed to the outside of a building and supplied from the building's internal wiring (714.1 (v)) and 714.411.3.4 has a stack of exceptions itself, including street lighting.

   - Andy.

Is this BS7671 requirement?

If so could you point out where it is?

I know domestic lighting needs RCD in all cases by regulation but I was not aware of anything like that for outdoor lighting.

Thats why I am asking

714.411.3.4 which states that outdoor lighting which is accessible to the public shall have additional protection by an earth leakage protection device with the characteristics specified in Regulation 415.1.1. which requires protection by 30mA device (RCBO or RCD)

“Lighting that is accessible to the public shall have additional protection by an RCD having the characteristics specified in Regulation 415.1.1. Examples include:

• gardens, spaces open to the public
• telephone kiosks
• bus shelters
• advertising panels and town plans.

This list is not exhaustive.

The following are excluded:

• Street lighting & traffic signage
• Illumination of monuments
• Platform lighting at rail / bus stations.

Now my reading of that is that the footballers flood lamps may need RCD protection, if not fenced off from the public, but a streetlamp illuminating the way in or out  of the grounds does not, even if accessible.

I assume but  do  not know for sure, that the thinking is that the loss of lights due to an RCD trip is less serious than the danger of unlit streets and footpaths, but for lights that are only  'nice to have' rather than traffic safety, the risk balance tips the other way. And perhaps given the sheer number of streetlamps on un-metered  supplies, it would be hard to arrange to install, and then test one RCD per lamp every six months.

Mike

This is another intesting one.

30mA for outdoor lighting lets say at my sons primary school, all well and good.

THEN

the street lamp outside the school gate only 3 meters away RCD is not needed or mandatory.

Maybe this is a JPEL64 question which could be tabled for discussion in the future

The streetlights were probably never put in to meet any version of BS7671 and may well have a non metered PME supply that would not pass the '7671 bonding requirements.

More seriously for a steel bodied tube, connected to the PME earth with a lamp at the top that is very much 'out of reach' what safety of life failure mode does an RCD protect against ? Collision by car or someone taking the door off to steal electricity perhaps, but the normal justification for an RCD  on lights, of folk drilling into cables in the wall  or contact with fraying flexes or other accidents while unskilled persons stand on a wobbly chair to change the lamp do not really apply,

The PEN connected pole is probably the biggest public hazard, and that is not really helped by an RCD.

Then working against the RCDs are the risk of false trips after  thunderstorms or other work on the network, and the non-occurrence of the regular testing - maybe like fire pumps, keeping the lights on, perhaps at a dangerous road junction, but with an N-E  fault present, is probably a lot less dangerous than letting them trip off.

The regs probably are right as they are- in most cases an RCD is not needed - and nothing prohibits you from fitting one if you decide that in that case it is.

 Mike

I find this an interesting phenomena that in this day and age there are installations which are
non metered PME
How do they bill the customer?  Do they just reply on the lamp wattage and multiply by 1000 to get Kwh and then say it is on for x amount of hours a day?  What happens when the light bulb is changes for a different model or brand?

Another thing I always say to people is

Under Normal Condition as apposed to Fault conditions.

In this case could a vehicle colide with a stree light outside a primary school.  Well yes it is possible, probable is more the answer.

The RCD or RCBO is to Normally provide Additional protection

As always BS7671 in the minimum and there is always the designer that design/plan from the intent of the Regs and go beyond it for safety. 

Do they just reply on the lamp wattage and multiply by 1000 to get Kwh and then say it is on for x amount of hours a day?  What happens when the light bulb is changes for a different model or brand?

Basically yes - it's billed by licence, the consumption based on the total nighttime and daytime consumption (things like photcells or radio switches will draw some power even when the lamp is off), control gear losses as well as lamp wattage. Ratio of light vs dark hours is pretty much averages out the same over a year where ever you are. When any of the equipment is upgraded the licence numbers are changed correspondingly - typically the local authority will know how many lampposts of each type they have, when one is upgraded they just decrease the count on the old type by one and increase the count on the new type by one.

   - Andy.

a vehicle collide with a stree light outside a primary school.  Well yes it is possible, probable is more the answer.

Certainly Not "probably" - by far the majority of lamp-posts will never ever get driven into and are eventually replaced for other reasons, usually age related corrosion or obsolete fittings that cannot be re-lamped with newer models - round our way many of one 1950s design had to be dug up and new ones "planted" when the change to LED took place, although some models of another later style were just re-headed.

Equally in known accident black-spots, where accidents are occurring at a rate of some few per decade,  where the risks are clearly higher than average, then an RCD might be worth consideration - or perhaps more  usefully a relocation of the offending lamp post....

Even so, you can crash into a lamp-post and if the vehicle is large/fast enough  it 'necks' sharply , cuts the cable and blows the fuse, or lighter vehicles, then often the tube leans over but remains intact, and the the wiring is never exposed. The Fire Brigade have special instructions for lamp-posts, fallen overhead cables etc, and do not cut them up willy nilly !! They are normally more worried about the vehicle catching fire.

  (The Manual of Firemanship is an interesting read - electrical starts around page 106 of the PDF.)

Mike.

and if an RCD is to be useful in a lighting column impact scenario, it would have to be located before the post, rather than inside it - which would be tricky since they're typically cabled direct from the street mains.

Additional protection is normally only useful where damage can expose live conductors without triggering ADS - (e.g. damage to soft sheathed cables) - with earthed steel conduit, MICC etc, that's pretty much impossible. Wiring inside an earthed/bonded steel lighting column would fall into a similar category I would have thought.

   - Andy.

and if an RCD is to be useful in a lighting column impact scenario, it would have to be located before the post, rather than inside it - which would be tricky since they're typically cabled direct from the street mains.

Additional protection is normally only useful where damage can expose live conductors without triggering ADS - (e.g. damage to soft sheathed cables) - with earthed steel conduit, MICC etc, that's pretty much impossible. Wiring inside an earthed/bonded steel lighting column would fall into a similar category I would have thought.

   - Andy.