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Need help for College paperwork


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Hello,

could anyone guide me and give me some idea about my paper work in college... this involve in workshop task...this year we are doing our task in a cubicle which is more realistic e.g working overhead using steps.

the task is really a basic one , installing a single way switch...

In our log sheet we need to write up and include the following

1. describe the continuity test which would be appropriate to testing this circuit

2. Explain the values you would expect to find for a good circuit

3.How does resistance compare with the lenght of the conductors and

cross sectional area?

Please any explanation will enlighten my mind

thank you all for your time and brill idea..

have a nice day

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Hello,

could anyone guide me and give me some idea about my paper work in college... this involve in workshop task...this year we are doing our task in a cubicle which is more realistic e.g working overhead using steps.

the task is really a basic one , installing a single way switch...

In our log sheet we need to write up and include the following

1. describe the continuity test which would be appropriate to testing this circuit

You need to go have a look at 10.3.1 Test procedures - continuity of CPC etc..

Starts Page 78 of One site guide to page 80.

2. Explain the values you would expect to find for a good circuit

You expect a low resistance value, proportional to the length and CSA of the circuit.

3.How does resistance compare with the length of the conductors and

cross sectional area?

You reference table 9A on page 166 of one site guide..

it has all of the standard cable sizes and their respective Resistance in miliohms per metre.

Please any explanation will enlighten my mind

thank you all for your time and brill idea..

have a nice day

for example.. if you had a 25m run of 1.5mm with 1.0mm CPC

the table on pg 166 gives you values for;

1.5mm conductor, (R1)

1.0mm conductor, (R2)

or combined 1.5mm & 1.0mm (R1+R2)

so:-

25m of 1.5mm is (25 x 12.10)/1000 = 0.302ohms (R1)

25m of 1.0mm is (25 x 18.10)/1000 = 0.453ohms (R2)

25m of 1.5mm is (25 x 30.20)/1000 = 0.755ohms (R1+R2)

so whether you are doing readings with a zeroed long-lead

or strapped Live-Earth to get R1+R2...

you should know roughly the value you will get on your meter based on the amount of cable you have installed and the CSA of the cables you have installed...

on our 25m of 1.5mm example If my R1+R2 was 0.84ohm I wouldn't be too woried...

but if I got 1.37ohm, I would be double checking my circuit for a bad termination at an accessory somewhere;)

HTHGuiness Drink

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The lower the resistance, the better - But it is to be equal to/less than0.05ohms

When the length increases - so does it's resistance.

When the csa of a conductor increases - the resistance decreases.

The smae applies with ambient temperature - the hotter it gets - the more resistance the conductor has.

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