Cable calculation. Calculating the live cable size only using the On Site Guide.
2024 ж. 22 Мам.
1 165 Рет қаралды
This video is mainly aimed at students on Level 2. The video shows a step by step method how to calculate the size on the live cable only using the On Site Guide. Each formula you need is shown and explained, each table used and page is shown in detail.
Finding Ib, In, It, Iz and all relevant C factors. Finding the reference methods, mV/A/m value and calculating volt drop.
BS7671 18th Edition amendment 2
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On - Site Guide 18th Edition amendment 2
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Casio Scientific Calculator
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Multi coloured pen
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15cm ruler
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30cm ruler
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Folding ruler
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Black writing pens
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Great knowledge refresher buddy. Keep up the good work
Thanks for the video. I've watched many KZhead videos on this topic but this is the first that solely uses the OSG and has clarified a few questions I had. Look forward to the series progressing and calculating conductors (and cpc) using BS 7671. Being flippant, do you think may sparks would use 16mm for a 5.5Kw shower?
Thanks for your supportive comments! I am glad to have helped you. To answer your question, if the circuit was designed as the example then yes, you must use 16mm cable. This design isn't really what you would find in the real world. The examples I use are to challenge you and expose you to all of the values that affect our calculations. I do apologise but I also get some mean enjoyment out of it 😂
10:49 Why not check Table F5 multi-core? Normally domestic is using T&E multi-core cable but why you check the single core table F4? thx
Hi there, I used the single core cable as that was what the question stated. Yes, you are correct, in a standard domestic setting, T&E is used. I'm trying to expose everyone to all sorts of tables that could be used in an exam question.
9:30 why do you no follow (OSG page 167) using it formula, but use iz instead ? And what is z & t stand for ?
We are using the same formula as page 167. It is telling you the In divide all of the C factors must be equal to or less the it value. I'm just giving the answer to this equation the symbol of iz. It is the tabulated current carrying capacity of the cable. Iz is the current carrying capacity for continuous service under particular conditions. Look on page 46 of BS7671