OP
amberleaf
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
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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