Many lighting professionals, those new to lighting, those not from an electrical background, or those with an electrical background that may need to be updated on the latest version of the wiring regulations (BS7671) will find this webinar invaluable.

Much has changed recently, with many Distribution Network Operators only making TT connection; the customer needs to make their own earthing arrangements. This change has impacts on the earthing arrangements for all other electrical street furniture within 2.5metres to ensure public safety. There are requirements now for surge protection and with different types of devices available, do they need to be supplied and if so what type? This webinar gives valuable information on these issues and many more as they affect exterior lighting installations.

This webinar coincides with the launch of the ILP online training course ‘Fundamental Lighting Electrical’, being an update to the one-day course previously held in Rugby. The course is available from the ILP online training platform, with discounts for ILP members and is essential to keep you abreast of current thinking.

Speaker: Jeff Lewis IEng MILP, self-employed lighting professional

Hosted by: David Coldron, Chair for ILP Manchester and members of the Committee

Q&As

QuestionAnswer

Does all lighting equipment now need to have surge protection devices?

No, but the designer must carry out a risk assessment and if failure of the equipment is likely to cause danger due to its nature then a surge protection device should be fitted.

Can you have different voltages on the same distribution pole?

Not usually, though it will happen where there is a transformer on the pole stepping the voltage down.
Do you need to go up the column to measure Zs?
Strictly speaking yes. However, in certain circumstances this may be impractical, for example if the equipment has been pre-wired and sealed by the manufacturer. By measuring Ze at the cut out (source) and using the cable manufacturers data to determine the values of R1 + R2 the value of Zs can be calculated.


With all the IoT being put into equipment – how do you screen the signal from mains?

Where this may be an issue then a screened cable would normally be used with the screen being connected to earth. The usual way of protection is by separation, keeping different circuits as far apart as possible.

Is it possible to accurately determine the Overhead Line voltage by counting the number of insulator discs? If yes, how?

There used to be a rule-of-thumb way of estimating the overhead line voltage by counting the ‘bulges’ on the insulators. However modern materials would put that in doubt and with accurate information now readily available why would you want to guess and put lives at risk?
What affect will the planned explosion in the EV charging infrastructure have on the on street lighting equipment?
This is an easy question to ask but very complicated to answer because the latest update (Amendment 1 2020) is still being ‘digested’ by the industry and many companies now are bringing out their own EV units with ‘special’ electronics that require very little earth leakage to trip, and EV’s employ different types of RCD’s. . I really don’t see in the longer term street lighting hosting EV’s…but who knows. I would suggest something like “EV charging infrastructure uses its own specific and dedicated equipment provided by the manufacturer and has specific requirements that may not be compatible with street lighting. EV charging is still evolving for example the development of inductive charging and vehicle to grid technology”.


For TT supplies, how can you provide an earth connection when many footways are so crowded with other services?

In congested footways, full of services or other underground obstructions, an earthing mat can be used. Earth mats are usually installed at about 600mm so would normally be above other services.
Do you cover bonding of extraneous bonding, ie Bus shelters?
For clarity because this is a fundamental course extraneous conductive part is something liable to introduce a potential, generally earth potential and not forming part of the installation. One possible example would be a metal hand rail where the decision to bond the rail and connect it to earth could in certain circumstances under fault conditions introduce a hazard. This is not included in the fundamental course.


How does a local authority manage multiple IDNO and
ICP along with the DNO on
the inventory?

This issue is all about information management. It is becoming the norm now for repair crews to have access to hand-held devices and these should carry service connection owners details. In some DNO areas, the host DNO has carried out emergency cover for IDNO networks. however, it is important that there is a service level agreement in place to cover emergency situations so and for stand-by staff to be aware of these.

Will the course be held in the next 12 months and will it be online or in person?

The source is available now for online delivery. Due to the current Covid restrictions we do not have any dates yet for face to face training delivery but that will change if there is a need and it can be delivered in a safe environment. Details of the course can be found at https://courses.theilp.org.uk/

Is there an end of course assessment for the training,
do you pass or fail?

There are 2 or 3 multiple choice questions at the end of each session and a multiple choice assessment at the end of the course. If you don’t get the answers right there is an opportunity to try again. Please don’t let this put you off.

Aren’t there issues with using RCD’s & RCBO’s in street lighting installations?

Early models of RCD’s were not popular in street lighting situations because they were prone to mains borne interference or nuisance tripping. Modern variants are much better, provided the installation have been inspected and tested. Retrofitting these devices without testing the installation is not recommended.

In order to take the course do we need to have any previous experience in specific topics?

No prior electrical or street lighting knowledge is necessary.

How would you deal with neutral current diversion
given the rise in broken PEN conductors?

Where there is a TT supply, it is important for the neutral conductor to be grounded frequently on its return path to the distribution transformer so if the neutral becomes disconnected there is a path to earth thereby protecting anything that comes into contact with the equipment being supplied.

BS EN 62305 suggests it does require surge protection! As it’s outside.

The fitting of SPD’s to protect against overvoltage is determined by a variety of risk factors from both external influences (atmospheric origin) and internal influences (spikes and surges in the supply). Also, where the site is located is also an important factor (flash density map) and where the supply comes from (See BS7671 Regulation 443.4 and 443.5).

Is there any amendments in the electrical test maximum results. IE Earth Loop Impedance etc?

Difficult to answer because no specific reference: There are many tables in BS7671 indicating Earth Fault Loop Impedance values, however TABLE 41-4  ELI for 5s disconnection has not changed, TABLE 41-3 ELI for 0.4s disconnection has not changed and TABLE 41-2 listing BS88-2, BS88-3 and BS3036 fuses has amendments (SEE PAGE 61 BS7671:2018).

Don’t most lanterns have
surge protection built into the lanterns now?

Because most street lighting is now LED and this uses sensitive electronic equipment, surge protection needs to be provided to protect it from mains borne transient voltages. However, if a luminaire is hit by a direct lightning strike the electronic equipment would be unlikely to survive.
Should you rely on maps of services given to you by DNOs?
Records of DNO networks are fluid and are constantly changing. There will be a disclaimer on all record drawings that they are an approximation of their position or depth. Most local authorities don’t have many records of their underground records either and those that do have them would probably say they are only approximate.

What course would you recommend as a ‘next step’ after Electrical Installations
for Lighting Professionals.
Is there a ‘follow on’ course being developed?

If there is a need for a more advanced course then it will be developed. However, if such a need is identified then it may be better to investigate more formal training through a local college.

What is the general rule for earth electrodes on a lighting installation (private cable network)? End of circuit and feeder pillar?

Each DNO operated area will have their own requirements, however as a general rule a private cable network of more than two columns would have an earth electrode at the source and one at the end of the circuit which in effect extends the PME network from the DNO. If the private cable network is more extensive then more earth electrodes would be needed to add stability to the earth path.

To add to Jeff’s answer on multiple voltages on one pole you will get 415 and 230 on the LV same pole.

Of course, but they are low voltage, the 230V being a single phase and 400V three phase

How will the course be delivered is it live? how much does it cost for members and non-members?

The course was originally developed for face to face delivery and has been adapted for online delivery. The sessions are pre-recorded so the student can stop them at any time and go back later. Once the course has started the student has 7 days to complete it, though this can be extended.

Could testing go to ten year intervals if you class it as a managed system use by trained and competent person?

A risk assessment would need to be carried out and the results of testing carefully scrutinised if that were to be done.

For private cable networks, should we always aim to
adopt loop in loop out to
avoid underground joints?

That’s a matter of personal choice. The loop system has the advantage that each cable can be tested individually so is simpler to identify a fault. However, for longer cable runs a jointed system may be better as room in the base compartment will be an issue for terminating larger cable sizes.

Will supply options for
passive safety be included?

Not at the moment.

You mention this is targeted
at architects yet the content tabled today doesn’t seem to relate to domestic scenarios?

The course is written for exterior lighting asset managers. However, the principles are applicable to domestic installations. There is a part of BS7671 that relates to highway electrical supplies, but most of the course is applicable to most disciplines.

As an electrical consultant working with LAs we are
asked more often now to design EVC as part of the street lighting infrastructure.
New install is not too much of a problem, but extension of existing can be. Big ‘watch it’ I think!

Yes, EV on-street charging facilities need to have a TT supply so all apparatus within a 2.5m zone must also have a TT supply, meaning there could be considerable work to carry out on other apparatus.

Does the course cover 3PHase cable calculations for EV charging units covering DC and AC circuits?

No, the calculations are simple single phase single circuit to demonstrate the use and effect of factors.

Do you still need to functionally test RCD every three months?

The frequency of RCD testing will be dependant of manufacturers recommendations and a risk assessment if longer periods are proposed.

Will earth rod installations be covered in more detail covering soil resistivity and how to achieve the magical figure if 20 ohms in poor ground condition?

No, this is a basic course to outline the issues with providing earthing. The course does go into soil conditions and the possible need for very long or multiple rods.

Are there any specific considerations associated with earthing lighting columns installed within insulated sleeves for either DNO or private connections?

I am not aware of any specific issues, other than the need for bonding. Concrete is also an insulator.

For Festive Lighting circuits on a DNO lighting columns, where there is a requirement of RCBO, is there a thumb rule or easy way  to determine its selectivity with a Fuse installed inside the DNO column?

Rule of thumb if you have no access to manufacturers data is 2:1, For example 20 amp source next fuse to guarantee discrimination is 10 amp.
Does an Earth electrode need to be installed at the end of fused radial spur circuits?
It was advised that where there are two or more units on a cable route, the IET guide to highway electrical street furniture advises:
Private cable networks
Where organisations run their own private cable networks from items of electrical street furniture then additional earthing requirements must be adhered to:
(a)   all installations must comply with the ESQCR and BS 7671 as applicable.
(b)   where an electrical circuit feeds three or more items of electrical street furniture then an earth rod or mat must be installed at the supply point and at the last or penultimate item on that circuit:
i. where a feeder column supplies an island with bollards and signs then it is usually impracticable to install earth rods on the island; and
ii. where a 3-phase system is used then an earth rod or mat should be installed at the last or penultimate unit on each phase.


Should we aim to avoid underground joints on a PCN, i.e. use loop in loop out?

Underground joints should not be a problem if they are installed correctly. However, care needs to be taken so supervisions is usually needed.

Where can I access information to join the course and sign up?

The course is available online now at https://courses.theilp.org.uk/

If you fail the course do
you just resit it or do you have to take the course again?

There are 2 or 3 multiple choice questions at the end of each session and a multiple choice assessment at the end of the course. If you don’t get the answers right there is an opportunity to try again. Please don’t let this put you off.

Is there any basic reading or knowledge that should
be expected before enrolling?

The course is aimed at those new to the industry, those without an electrical background and those that want to update their knowledge.

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