***Useful Information For The Working Sparky***

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Should I identify black or grey as neutral on harmonised single phase cables ?
Technically, when any cable is over-sleeved or marked (with the exception of single-core green/yellow which must not be over-sleeved or marked), the over-sleeve or marking takes precedence over any colour underneath and therefore any combination can be used.

However, a convention has been generally accepted of over sleeving or marking the black with green/yellow (CPC) and the grey with blue (Neutral).

The thinking behind this has been done with the aim of helping disassociate the colour black with neutral and the shade of grey being a neutral colour.

How Long Can Meter Tails Be ?
The length of Tails from the Meter to the Consumers Distribution Board or Consumer Unit is at the discretion the Local Electricity Company.

Generally the maximum length of tails allowed is 3 metres. For longer distances it is common practice to install a Double Pole Isolation Switch at the Meter Position and install tails or a Sub-Main to the Consumers Distribution Board. Care should be taken to install adequate mechanical protection to the Tails or Sub-Main cable.

SWA is preferable if the cable is not to be clipped direct to surface. Minimum size of Meter Tails is 25 sq mm Onsite Guide Section 2

Building Regulations confirm...

...that when a hole is cut into a fire rated ceiling to fit a downlight, the fire stopping ability of the ceiling is impaired. In the event of a fire, flames could penetrate through the light fitting and spread to the floor above with the subsequent risk to life and property. The downlight itself can also be a source of fire due to the high temperature of lamps and the promixity to flammable material.

To provide total peace of mind and total protection, a Fire hood downlight cover should be installed over the light fitting if the ceiling is a fire separating element. Fire hoods will stop the spread of fire for at least 60 minutes. In fact, recent tests by Chiltern International have demonstrated that Fire hood downlight covers can give added peace of mind by providing up to 2 hours protection from fire.

When Fire hood / downlight covers are fitted as part of the ceiling structure they become in effect a permanent fixture. This means that the fire protection with Fire hood remains even when fashion may dictate a change of light fittings.

“Building Regulations 2000 Approved Document P allocates full responsibility to the electrician to make good the fire performance of any fire-rated floor/ceiling/wall after carrying out an electrical installation and legal action can be taken for non-compliance. Many, so called fire rated downlight fittings/covers are only tested in a small number of ceiling constructions and consequently this leaves the electrician vulnerable to “legal action” if the solution that he uses is wrong for the installation."

Types of Smoke Alarm Sensor : The following smoke alarm sensor types are suitable for different applications.

Optical :
Sensitive to larger smoke particles produced by smouldering fires like furniture. Suitable for mounting in landings and hallways to reduce false alarms from kitchens but not in steamy areas near to showers or bathrooms.
Ionisation :
Sensitive to smaller invisible particles in smoke which can be produced from cooking. Suitable for dusty or occasionally Smokey locations as they are less sensitive to more dense smoke particles. More likely to cause false alarms than the Optical when near kitchens.

Heat:
Not sensitive to any smoke.

Suitable for kitchens but only when linked to smoke detectors which are mounted in circulation areas such as hallways and landings.

Sitting :
Must be at least 300mm from a wall, corner or light fitting.
On sloping ceilings sensors must be 900mm (horizontally) from apex.At least one on each floor area (hall & landing).One sensor between lounge or kitchen and bedrooms.

Linking :
A mains voltage system requires linking between sensors with 3 core & earth cabling, however radio frequency or Radio Link bases can be used to prevent the need for wiring.

Sounders :
Each mains or battery operated sensor must incorporate an integral sounder.

Part P of the building Regulations deals with Fire Safety in dwellings.

For the Deaf & Hearing Impaired : Smoke & Heat Alarms
People with hearing difficulties require a different approach to fire protection, a conventional alarm sounder will not be sufficient for their needs.

System Features & Benefits :
• Control panel with rechargeable battery back-up, mains power supply lead and 13 amp Plug
• High intensity integral strobe light
• Auxiliary socket for connection of additional optional strobe lights
• Vibrating pad for placing under a pillow or mattress
• Capability for interconnection of up to 12 smoke alarms
• Test button on control panel for testing the system
• Connections are monitored to check integrity of system
• Alarm clock input facility
• Remote trigger option
• Pager output facility

 

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Inefficient Incandescent (GLS) Lamps to go ←←
Over an eight year period the ‘old type GLS’ land inefficient lamps will disappear from the shelves of suppliers and their sale will be prohibited within the EU. The EU directive begins in September 2009 with lamps of 80 Watts or higher, as well as all frosted (non-energy saving) lamps.

By 2012, most lamps of greater than 7 watts will be withdrawn from sale. Special purpose incandescent lamps (e.g. those used in household appliances such as ovens or fridges, traffic lights, infrared lamps etc.) are meant to be exempt from the measure, as they cannot fulfil the efficiency requirements and most of the time there is no alternative lamp technology.

The table below shows when certain requirements will be enforced and also displays some examples of the types of lamps, commonly used in households that will be affected by the new requirements.

* 1 Sept 2009 Lamps rated at 100w or more must carry an energy rating of C or better. All others may carry E : Lamp types prohibited from retail (common in households) [1] Clear incandescent and conventional halogen lamps rated at 100w or more [2] All frosted lamps excluding those carrying an energy rating of A (CFLs) * 1 Sept 2010 Lamps rated at 75w or more must carry an energy rating of C or better. Lamp types prohibited from retail (common in households) Clear incandescent and conventional halogen lamps rated at 75W or more : * 1 Sept 2011 Lamps rated at 60w or more must carry an energy rating of C or better. Lamp types prohibited from retail (common in households) Clear incandescent and conventional halogen lamps rated at 60w or more * 1 Sept 2012 Lamps must carry an energy rating of C or better All clear incandescent and conventional halogens : Lamp types prohibited from retail (common in households) ( Halogen lamps rated B & C still ok ) * 1 Sept 2013 Raising of quality requirements followed by a review * 1 Sept 2016 Lamps must carry an energy rating of B or better with 1 exception : Lamp types prohibited from retail (common in households) All lamps carrying an energy rating of C except special cap halogens (C rating

Spotlamps and other directed or reflected lamps will not be regulated until a second directive is drawn up at the end of 2009.

Halogen lamps with special caps like G9 do not exist with energy classes better than C. They are needed on the market as there are luminaires that can only take such lamps. Therefore further improvements can only be achieved by imposing requirements on the luminaires themselves, which the Commission is planning to do in a measure currently under preparation and to be tabled in 2009.

Halogen dichroic spots & floods which are widely used in surface mounted and recessed lighting applications, have a higher light output for power used and therefore lamps with an energy rating of C or better will not be phased out.

 

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to view the effects of installing a floodlight at various angles :

domestic locations is a 250 or 500 watt tungsten halogen floodlight controlled by a movement sensor (passive infra-red, PIR).

90o - At an angle of 90 o degrees from the vertical, the light is shining directly outwards, making it impossible for onlookers to see any criminal activity.

At 67o, the problems persist as at 90o degrees, making your "security" light a serious security risk.

45 o - The floodlight has an opening angle of 72o degrees, and so the light needs to be angled at less than half that (i.e. less than 36o) to illuminate the background (in this case, a wall).

At 22o, the floodlight begins to become a security aid. The house wall is illuminated, and so any intruder is highlighted against the background even if (as in this case) the background (i.e. the gate) is dark. However, when standing close by, the light source is still visible, which impedes the ability of a nearby witness to identify an intruder.

O o - Pointing a floodlight directly downwards is the best solution. The background wall is illuminated, and the bulb of the floodlight is no longer visible, making it easier on the eye. However, the floodlight is still over-powered (in this case, a 500W bulb); such a bulb will always generate strong shadows for people to hide in. The best overall solution is a floodlight pointing directly downwards whilst using a low powered bulb (60-120W will aid onlookers, without generating glare).

 

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Wiring within the trunking should be to a maximum of 45% of the available capacity in line with IEE wiring regulations.

* It is important to maintain electrical continuity between the cover and the base for the integrity of the system, and adherence to standards.

 

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The customer

Following initial verification, BS 7671 requires that an Electrical Installation Certificate, together with a schedule of test results and an inspection schedule, should be given to the person ordering the work. Until this has been done, the Regulations have not been met.
Sometimes the person ordering the work is not the end-user, e.g. the builder of a new housing estate sells the individual houses to various occupiers. In these cases it is recommended that copies of the inspection and test certificates, together with a test results schedule, are passed on to the new owners.

Handover to customer

Handover of the installation to the customer is the final task. This should include a tour of the installation, an explanation of any specific controls or settings and, where necessary, a demonstration of any particularly complicated control systems. The operation and maintenance manuals produced for the project should be formally handed to the customer at this stage, including copies of the Electrical Installation Certificate, the Schedule of Test Results and the Inspection Schedule

Activity
1. Obtain copies of the Electrical Installation Certificates, Inspection Schedules and Schedules of Test Results for your home or the site that you are currently working on. If the building is old enough these will also be accompanied by one or more Periodic Inspection Reports. If you can, compare these with the current installation to see if any alterations or additions have been made since they were prepared.

2. Have a look at any test equipment you have access to and see when and how it was last calibrated and when it is next due for calibration.

3. If you have not done any ‘real’ inspection and testing before, you might like to’ work shadow’ someone while they are carrying out an inspection and testing of an installation

Functional testing of residual current devices (RCDs)

Where a residual current device (RCD) fails to trip when pressing the integral test button, this would indicate a mechanical fault within the device itself, which should therefore be replaced.

When a residual current device fails to trip when being tested by an RCD tester, this would suggest that there is a fault with the RCD and that it should be replaced. It maybe that there is an issue with the cpc; however a test of the earth-loop impedance would prove whether this is satisfactory or not.

If the RCD does trip out, but not within the time specified, then a check should be made that the test instrument is set correctly for the nominal tripping current of the device under test. If the correct tripping current was selected then this indicates that the would fail to give the protection required and, therefore, would need replacing.

A RCD is fitted to the circuit for safety and protection. If the device is not working, then the installation is not protected and people and livestock are at risk of electric shock

Initial verification procedures

In order to make sure that this work is carried out satisfactorily the inspection and test procedure must be carefully planned and carried out and the results correctly documented .
We inspect and commission material after the completion of work for three key reasons to ensure:

* compliance with BS 7671
* compliance with the project specification (commissioning )
* that it is safe to use.

 

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Portable Appliance Testing - PATS

Examples of Bad Practice

No matter how well maintained you believe your electrical system to be there can be faults or unsafe areas that need correcting. Below are some of the more common problem areas.

Common Office Hazards

Incorrect Fuse Rating

Incorrect Polarity

Un-earthed appliances

Splits in cables

Trapped cables, between objects. (example: between desks and walls)

Trapped Cables (example; in floor boxes)

Overloading of sockets by 'piggy-backing' extension leads

Incorrect use of extension cables

Use of double adapters

Unsheathed pins on plugs

Un-earthed metal frame desks

Trailing leads

Water vessels near to electrical points

No access to sockets to disconnect in an emergency

Equipment such as fan heaters getting clogged and overheating

Dust clogging electrical equipment

Extension Leads

Extension leads are also considered as portable equipment and should be avoided where possible. If used, they should be tested as portable appliances. It is recommended that 3-core leads (including a protective earthing conductor) be used.

A standard 13 A 3-pin extension socket-outlet with a 2-core cable should never be used even if the appliance to be used is Class II, as it would not provide protection against electric shock if used at any time with an item of Class I equipment.

** Class I equipment is earthed and contains metal parts, e.g. storage heaters, washing machines
** Class II equipment is not earthed and is usually in a plastic case, e.g. hairdryers, fans

Guidance for Schools & Colleges

Headteachers and others responsible for the safety of pupils and staff need to ensure that electrical equipment is regularly maintained and electrical hazards are identified and dealt with promptly.

The Health and Safety at Work Act and The Electricity at Work Regulations cover the legal requirements for electrical safety and apply to all places for work, including educational establishments.

Under the Regulations, every employer has a duty to ensure that all reasonable precautions are taken to achieve electrical safety. In the case of schools and colleges, the headteacher will normally be regarded as the principal 'duty holder'. The principal duty holder is required to:

• ensure that installation, repair and maintenance work is only carried out by competent persons
• confirm the safety of equipment by arranging periodic inspection and testing and any necessary maintenance work
• implement and maintain safety procedures for all electrical equipment in use.

 

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If adhesive tape is used , then it has been bicoloured : ( PEN )

* PEN ; conductors’ ( when insulated ) are either
Green & yellow : throughout their length . with blue markings at the terminations : or

Blue : throughout their length . with Green & yellow : markings at the terminations :

* Bare conductors’ are painted or identified by a coloured tape , sleeve or disk ,

 

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Electrical Supply July 2009

a) Provision of supply
The supply into a hazardous area should be directly from a main switch isolator and not from a ring main feeding other parts of the site. The switch isolator must isolate all live and neutral conductors.

b) Type of Supply
The form of earthing defines the types of electrical supply used on a site.
* TT system, a system having one point of the source of energy directly earthed, the exposed-conductive-parts of the installation being connected to earth electrodes electrically independent of the earth electrodes of the source;
* TN system, a system having one or more points of the source of energy directly earthed, the exposed-conductive-parts of the installation being connected to that point by protective conductors;
* TN-C system, a system in which neutral and protective functions are combined in a single conductor throughout the system;
* TN-S system, a system having separate neutral and protective conductors thought the system;
* TN-C-S system, a system in which neutral and protective functions are combined in a single conductor in part of the system;
* IT system, a system having no direct connection between live parts and Earth, the exposed-conductive-parts of the electrical installation being earthed.

For new installations the electrical supplies into a hazardous area should be TT, although TN-S, may be acceptable.

TN-C-S (PME) may only be used on existing installations subject to an
appropriate, documented, risk assessment being carried out and that the
installation is subjected to regular checks on the current on the diverted neutral
current. For these installations it may be more practical to install a “derived TT
system” for the equipment in the potentially hazardous area.
b) Cable sizing
All electrical power cables must be designed and sized by a competent electrician/designer.
The design and cable sizing needs to take into account a variety of factors including:
* Length of the cable(s),
* Proposed method of installation (e.g. underground buried, underground in duct, above ground on trays),
* Type of load (motors, heaters)
* The maximum load, (most LPG pump motors, especially single phase, take a high starting current),
* Current

Information on cable design is available from tables in the 17th Edition Electrical Regulations ,

c) Voltage
Tests should be carried out installations to confirm there are no excessive voltage drops. (e.g. due to length of cable, connections from the incoming supply to contactors/cables, contactors/switches.) The voltage drop to the extremity of the circuit should not exceed 5%; more information in BS7671.

The available voltage at any motor should remain within the tolerances specified by the motor manufacturer both for start up and during running.

d) Protection against Electric Shock
When a different type of supply is used for the hazardous area compared with the supply to other parts of the site there must be a suitable separation, typically in excess of 2.5 metres, between un-insulated components to prevent
inadvertent contact between the two.

e) Site Earthing
Site earthing is required for all sizes of storage vessel, when the installation is fitted with electrical equipment, the primary requirement being protection against electric shock. This is not the same as the earthing required for the dissipation of static electricity; see
5 i). Earthing figures for bonding should meet those given in BS 7671.

An earth-bonding conductor should be run back to a primary earthing point at the source of energy. For a TN-S system this is where all metallic parts will ultimately be bonded.

The electrical supply must have a suitable effective earth. A “split” earth bar and test socket should be installed for each installation to allow testing of the earthing efficiency.

Bonding to other services must be connected to earth and comply with BS7671.

Notes:
• The armour of SWA cable should not be used as an earth conductor.
• Installations using cathodic protection systems for corrosion protection of vessels or pipework require special consideration and expert advice should be sought. the current rating of the type, the type of load (e.g. motor, heater etc), its short circuit capability and earthing impedance values, which need to be evaluated on site to ensure compliance with BS7671.

g) RCDs
Every power circuits into potentially hazardous areas should be protected by a Residual Current Device (RCD) being capable of disconnecting all poles including neutral of the circuit having a disconnection time of not more than 30ms.

h) Generators
Special precautions are required when a generator is to be used either during normal operations or more importantly in emergencies (see BS7671).

5. Installation of Equipment
a) Motor overload/low voltage protection

BS 7671 requires that every electric motor having a rating exceeding 0.37 kW be provided with control equipment incorporating means of protection against overload of the motor. Every motor needs to be provided with means to prevent automatic restarting after a stoppage due to a drop in voltage or failure of supply.

b) Cables
Cable conductors should only be of copper.
Power cables with integral mechanical protection are preferred, non-armoured cables can only be used providing the cable is protected by another method against mechanical damage.
Earthing cable sizes need to be assessed for each site prior to installation. 25mm2 should be adequate for most installations, should a smaller cable be considered then the appropriate calculations need to be carried out before installation.

c) Glands
Cable glands should be suitable for the relevant zone or area, the type of equipment being connected, the connection thread and for the cable being used. They should also maintain the Ingress Protection of the equipment.

d) Auxiliary equipment
Any auxiliary electrical equipment (e.g. solenoid valves) should be suitably protected (e.g. using an individual RCD) in the event of failure of the equipment. This protection should not be incorporated into hazardous area enclosures unless written approval is received from the manufacturer.

e) Enclosures of equipment for use in potentially Hazardous/Protected Areas
Any modification of the enclosures after dispatch from the manufacturer will invalidate the electrical certification for use in hazardous areas and must not be carried out.

f) Emergency Switch
A suitable switching device for emergency use should be fitted outside the potentially hazardous areas or separation distance (whichever is greater). When operated this would disconnect all electrical supplies (live and neutral conductors) to the associated equipment. It may be preferable to leave some auxiliary circuits live; e.g. lighting for the area, gas detection systems etc.

Except where failure to start after a brief interruption would be likely to cause greater danger; the installation should incorporate a system so that following the loss of power (e.g. power cut) power is not restored automatically but needs to be reset manually by an authorised person. This may be incorporated with the switching device in the above paragraph.

g) Isolation
Where required by BS7671 and BSEN60079–14 a means to secure the isolation in the off position shall be provided for the equipment in the potentially hazardous areas.

h) Switching off for mechanical maintenance
A means of switching off and isolating the power supply for mechanical maintenance should be provided for any electrical equipment in accordance with BS7671 and BSEN60079-14.

 

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i) Earthing
Earthing arrangements should be assessed for each site prior to installation. Metallic sections of an installation should be designed, installed and tested to confirm they are electrically connected. For equipment not mounted on common
steelwork each component may need to be electrically connected, using an appropriately sized conductor, back to a single point.
The use of electrical connections across mechanical joints is not necessary providing, after installation, electrical conductivity is checked and confirmed to be acceptable. This should be checked periodically at intervals not exceeding 2 years.

Consideration should be given as to whether earthing of metallic items within a distance of 2.5 metres is also required. e.g. adjacent metallic fencing. Care should be taken to ensure that surface features (e.g. powder coating) do not render surfaces insulating.

For installation the incorporate Cathodic Protection systems suitable measures will need to be taken to ensure the parts of the installation protected by the CP system are not connected to the electrical system earth. Electrical isolators (with static build up protection) may need to be incorporated into the installation.

system are not connected to the electrical system earth. Electrical isolators (with static build up protection) may need to be incorporated into the installation.

j) Static earthing
Before connecting a vessel to a local earth rod an assessment is required to see if this would affect the protection of the total installation. It may be necessary to supply a separate “clean” earth for a delivery tanker earth connection.

k) Sodium lamps
Due to the potential hazard of ignition if a lamp is dropped or falls sodium lamps should not be installed within or above zone 0 or 1 areas. Before changing such lamps above zone 2 areas the area should be checked to confirm there is no flammable atmosphere present.

l) Redundant cables or cores
Any redundant cables/cores should either be removed or terminated in a suitable enclosure.

m) Multistrand cables
To prevent loose strands the terminations of these cables should be fitted with crimped or similar ends.

6. Testing/documentation
a) Initial inspection
All new installations and equipment should be subject to a detailed inspection as part of the commissioning, suitable documentation should be issued on satisfactory testing of the installation. Typical information is given in Appendix 1.
On completion DSEAR requires a register of the electrical components, their relevant zone of installation and the equipment approvals. Typical register layout is given in Appendix 2

b) Periodic Inspection
This is the routine inspection of all equipment, systems and installations and information is given in BS EN 60079-17. An assessment should be made, and recorded, at the time of issuing the initial inspection of:

˃The type of inspections required usually visual or close
˃ The period between inspections.

installations these are normally 12 months but must not exceed 3 years)

Visual and close inspections can be carried out without removing any covers or isolating the power.
The results of all inspections should be recorded.

c) Detailed inspection
In addition to any other periodic inspections a detailed inspection should be carried out at intervals to be determined by the competent electrician (usually not exceeding 5 years) or after any modifications to equipment and/or wiring. Modifications being defined as any change to the wiring, circuits or the replacement of items that are not identical to the one removed.

The next electrical survey will be due no later than ------------ 12 months from the
date of this document. ---------- (Delete as applicable.)
Signed: -------------- Name: ------------
Date: ----------
Qualification for hazardous area work: -------------------

This Schedule relates only to Certificate/Report Reference

Cable type :
A ) PVC/PVC cables
B ) PVC cables in metal conduit
C ) PVC cables in non-metal conduit
D ) PVC cables in metal trunking
E ) PVC cables in non-metal trunking
F ) PVC/SWA cables
G ) XLPE/SWA cables
H ) Mineral Insulated cables
Other ?
Extent covered by this schedule

Stripping out of Redundant Installation

1) All redundant installations shall be stripped out as far as practical. Where this exercise could lead to any future confusion labels shall be installed giving clear concise instructions.

2) Where the stripping out of redundant installation is specified, the work shall be carried out with the same care and attention as for a new installation, and the Contractor shall ensure that no damage to the building fabric or equipment ensues.

3) Under no circumstances shall the Contractor allow any of his own, or any other Contractor’s or Sub-Contractors operatives to disconnect or cut a live cable, or cut conduit / trunking containing ANY cables.

 

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extract taken from wiring maters 2009

Conclusion
When carrying out additions or alterations to existing electrical installations, the reconfigured aspect of the electrical installation should comply with BS 7671:2008. The installer does not simply take responsibility for the newly installed or reconfigured element of the installation but all parts of the circuit(s) worked on - including the need to comment on the continued suitability or
otherwise of the equipment belonging to the distributor - this includes the condition of the metering equipment,
supply and meter-tails, distribution equipment and the earthing and bonding arrangements. If the client does not want to pay for
upgrades to existing equipment, this does not absolve the installer from responsibility, nor does a disclaimer.