This article will deal with the electrical earth arrangements in a domestic dwelling in the UK. Contrary to a lot of peoples notions the earth is very necessary.
Why do we have an earth in our houses? To answer that requires a little explanation of how electricity reaches our homes and how fuses work.
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Electricity is generated at power stations or similar installations,
wind farms, hydro-electric turbines etc. These plants generate the electricity which is the transformed up to around four hundred thousand volts and distributed around the country via the national grid.
It is easy and cost effective to transport electricity at these incredibly high voltages but obviously it once again has to be transformed back down to 230 volts for use in the house.
At the transformer the centre of the winding is connected via rods or mats, to the earth. This earthing of the winding provides a reference point, nominally zero volts. Electricity is then supplied at 230 volts to this reference.
To be useful electricity requires a circuit. The electricity must flow from a source, through the device whatever it may be, kettle, iron cooker etc. and return to that source.
To protect the cable in which it flows the amount of electricity must not exceed the capability of the cable. This would be an overload in the long term, in the short term a fault in the cable or any device attached to it will cause a large amount of electricity to flow and it is this that blows the fuse.
The amount of electricity needed to blow a fuse is determined by the rating of the fuse itself, i.e. a current of around 1.6 times the fuse rating is required to operate a re-wirable fuse so a 20A fuse will need approximately 32 amps.
To facilitate the quick and efficient operation of the fuse the electrical earth provides a quick route back to the source, that is the transformer. The better the return path, the more electricity flows and the quicker the fuse operates.
The circuit that the live conductor and the earthing conductor form is called the earth loop. The earth loop is measured with a special tester and must conform to certain constraints for the variety of fuses available.
The requirements for each type of fuse, properly called a protective device, are laid down in the wiring regulations. The electrical earth therefore, is extremely important for the safety of any user of electrical system. The absence of the earthing conductor means that any fault on the system will not operate the fuse until you or one of your family becomes that missing part.
Christmas Sales Bosch DDS180-02 18-Volt Compact Tough Drill Driver with 2 1.3Ah Batteries 201
Dec 24, 2011 00:01:22
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Christmas Sales Bosch DDS180-02 18-Volt Compact Tough Drill Driver with 2 1.3Ah Batteries Feature
- 4-Pole High Performance Motor - For maximum power in the most compact size
- New Patented Gear Train and Clutch - Enables most compact design in its class and lightest weight
- Flexible Power System - Both DD and HDD are compatible with every 18V Li-ion Bosch battery
- Ergonomic Grip Zone - Smallest diameter in market enables better gripping and greater comfort
- New Ergonomic Design - Modified orientation relative to handle increase comfort
Christmas Sales Bosch DDS180-02 18-Volt Compact Tough Drill Driver with 2 1.3Ah Batteries Overview
Includes 18V Cordless Lithium-Ion Compact Tough 1/2-in Drill/Driver - DDS180-02, (2) 18V Slim Pack Lithium-Ion 1.3 Ah Batteries, 30 Minute Li-Ion Charger, Carrying CaseChristmas Sales Bosch DDS180-02 18-Volt Compact Tough Drill Driver with 2 1.3Ah Batteries Specifications
Ready for all materials from wood to metal, the compact yet powerful Bosch DDS180-02 Compact Tough 18-volt lithium-ion 1/2-inch drill/driver's 7-inch head length is the smallest in its class, yet it delivers top heavy-duty drilling performance. It works with all Bosch 18-volt lithium-ion batteries, and this kit includes two 1.3 Ah Slim Pack batteries to help keep things light.
Fast Speeds, High Torque, and Durable Construction
The DDS180-02 is optimized to worke at two speeds--one for high-torque applications (0-500 RPM) and one for high-speed applications (1,700 RPM)--and it provides a maximum of 600 inch-pounds of torque. The 4-pole open-frame motor and newly developed gearbox provide exceptional power for such a compact drill/driver. The 18+1 clutch settings included in this Compact Tough model and a variable-speed trigger help you match the best speed to the job, so you can achieve precise results. It can drive 500 screws per charge using the BAT619G 3.0 Ah HC battery (not included).
Balanced Design and Easy Bit Changes
This drill/driver's Durashield housing is constructed with ABS/nylon composite, which makes the housing flexible on impact. Unlike competitive tools, which use a conventional plastic housing, Durashield will not crack and can easily withstand 10-foot drops.
The ergonomically designed handle and soft-grip wrapped housing offer a comfortable fit for extended working time. The DDS180-02 comes complete with a single-sleeve 1/2-inch auto-lock chuck for one-handed bit changes, as well as increased drill-bit capacity for versatility. And for even greater convenience, LEDs provide illumination when you are working in dark or enclosed areas.
Flexible Power System
Like all tools in Bosch's 18-volt line, this drill/driver can be used with either a 1.3 Ah Slim Pack battery (model BAT609), a 2.6-Ah Fat Pack battery (model BAT618), or a 3.0 Ah Fat Pack HC batter (model BAT619G). If you're looking for a lightweight option, the Slim Pack is the perfect choice. If longer runtime is what you need, the Fat Pack will do the job.
ProVantage GuaranteeThe DDS180-02 comes with the ProVantage three-year protection plan, which guarantees two years of battery protection and one year of tool protection. Under this plan, you can receive two years of free battery replacements, tool replacement for one year, and a free tool repair package for the second and third years. |
What's in the BoxOne Bosch DDS180-02 Compact Tough drill/driver kit with two 18-volt lithium-ion 1.3 Ah Slim Pack batteries, one 30-minute charger, one carrying case, bits, and operating instructions. |
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