# calculations

1. ### UK Hotel extension cable calculations

So I've calculated my hotel lighting and 1 circuit has an (ib) of 0.33a and I put a 6a breaker on it (in) then got my (iz) 5.8a which is suppose to be equal to (in) or greater right but it's not so what should I do to change this. By the way my (ca) is 1.03 my (cg, ci, cf,) are all 1. Please...
2. ### 3 wire Delta calculations

I have a question on 3 wire Delta connected winding with Phase Supply between X, Y & Z is 370 Volts. What is the voltage between One Phase 'X' and the center tap of the opposite winding? See attached doc.
3. ### SWA cable calculations!!

Ive been asked to confirm the maxium possible supply for an existing SWA sub main and I know im doing something wrong with my cable calculations. Its a 10mm 3 core SWA currently on a b40 on a split load boad but its about 120m run ( direct burial) and they want to run an airsource heat pump...
4. ### Trainee Am2 calculations on test sheet

I’ve got my am2 tomorrow morning, I’m pretty confident with everything and just gone over my testing and done the prep day yesterday, I was just wondering if anyone knows what calculations are needed on the back of your testing sheet to pass? I’ve got r1+r2/4 for ring final, zs=ze+r1+r2, my...
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### Cable calculations for pricing

Ok guys it's back to school for me.... Since leaving college I have prided myself into thinking what a great electrician I am, only now that I am starting to take on my own projects from scratch it has become apparent that I am a little rusty on the theory side! Turning up as a subby, no...
6. ### Is the IEC 60909 standard applicable for short circuit current calculations in UK?

Hi. I would like to get a help from this forum electrical engineers. There is the international standard “IEC 60909” for calculations of symmetrical and asymmetrical short circuit currents. I need to calculate line-to-earth short circuit (circuit 0.4kV) by the software that uses calculation...
7. ### Voltage drop and cable size calculations.

Hi, would like ta post a question about voltage drop in a cable. If I have a 230v single phase load of 500w with a 50 meter cable run reference method C . What would be the voltage drop in a 1.5mm2 ? From my calculations excluding pf I checked from the table the the voltage drop in mV/A/m of a...
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### Question regarding Voltage Drop Calculations

When one is calculating the voltage drop of a circuit, one must determine the length of said circuit. However, I am not sure whether the length of the circuit includes the length of both the Live conductor running out from the consumer unit to the furthest circuit AND the Neutral conductor...
9. ### True Power Calculations

Hi guys, hopefully, maybe, someone will be able to help me with this one. Trying to get my head around true power calculations and am really struggling to understand it. So the scenario goes; Three coils of resistance 40 Ω and inductive reactance 30 Ω are connected in delta to a 400 V...
10. ### Help with CPC size

Hi I am training to become an electrician. I have a problem to solve to work out the size of the CPC. My calculations say I would use 6mm and 1mm CPC. This can't be right, can it? Please refer to attached document for details.
11. ### Cable calculations

Can anyone help me out how to find minimum kva? The question is, determine the minimum KVA, you have 0.5kw, 12v motor and a power factor of 0.8 cheers
12. ### Cooker circuit and diversity.

Evening all. Customer needs a new oven and electric hob. The current setup is 6mm T+E on 32A MCB, RCD protected, about 8M run, reference method 100. The oven they are looking at is 10.5KW. I initially thought that was too much but after adding diversity it seems ok. Are my calculations ok as I...
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### Voltage drop calculation

Hello everyone just want a little help how you would calculate the volt drop if 230 single phase heater circuit line & neutral conductors combined resistance of 0.68 Temperature at 20 degrees and load current of 16A? show calculations got this in my 2395 today wanna make sure I used the...
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### Wind Calculations

Hi Had our two day MCS audit this week. Three technologies produced two non conformances . Solar PV and solar thermal ...no wind load calculations. Having read the entire section on wind calculations I am still at a loss as to how to do the calculation and what to do with the figure when...
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### Android app EasyEngineer

https://play.google.com/store/apps/details?id=easyn1.easy.EasyEngineer&feature=search_result#?t=W251bGwsMSwxLDEsImVhc3luMS5lYXN5LkVhc3lFbmdpbmVlciJd Only for screens with 4'' and less. With EasyEngineer you have more than 180 calculations available, divided in 6 areas. It's a huge...
16. ### Working out resistor calculations...

Late at night....tearing my hair out....need help with working out resistor calcs. 230V supply....R1=70...R2=90 What is the value of a resistor which when connected in parallel with 70 ohm resistor will cause a total current of 2.4 amps to flow in the circuit? any guidence to push me in the...
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### Books you swear by... Whats in your collection?

Can anyone recommend some good electrical books? I feel I need to update my collection. The ones I have are not only the regs and the O.S.G but also: Advanced Electrical Installation Work. Electrical Installation Work - Brian Scadden. Electrical Installations Level 2 and 3 - Heinemann...
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### CU Change for assessment

Ive changed a CU for my assessment and rewired the upstairs lights due to no cpc, will the assessor want to see calculations for cable size and voltage drop for rewiring the lights? and will he want max demand/diversity calculations for the CU and on the inspections, what happens if a box...
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### hey all,anybody know best book for understanding formulas

struggling with getting my head round formulas,anybody know any books which are good or any tips...cheers
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### Power to an out building

Say you wanted to power a shed office, or somethign similar, and lets say it's up the end a garden. Would you split at the meter to an isolator switch or a breaker then swa all the way up to a new CU. Then for earth would you have to use an earth spike instead of the earth down the armoured...
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### Differential Protection testing of a 3-phase transformer

For Differential protection testing of a three phase Power T/F using secondary injection test set, how do we know the correct value of current to pe applied(value at which relay picks up)? Does OEM provide these values in Instruction manual or Electrical Engineers calculate these values...