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# formula

1. ### 18th Edition Formula Questions - Any Genuine Examples

Hi, Firstly, sorry if this post is in the wrong sub-forum group; if it is please advise where to place this thread. I've been studying for the 18th Ed. Regs course via XS Training and all is going really well. The only problem is that I've noticed all their practice material/questions haven't...
2. ### delta transfomer current

Hi All, anybody know the formula to find current on delta transformer?
3. ### RFC cross connect formula

I may have asked this question before but I forgot what was said and the problem has reered it's ugly head again. I was doing some RFC testing the other day. Did my cross connecting but when I was doing the calcs I kept getting the wrong figure. It seemed I was not pressing = before dividing by...
4. ### Trainee Any tips ?? Remembering formula

Hey I’m studying 2365 at college and I’m at the science part now .. any tips on remembering formula or is it just a case of going over and over it till it’s in your head .. any help much appreciated
5. ### excel formula Help

hi all small formula issue can anyone help got the basics can add, multiply, ect copy columns, but need a multiple column (sum) entry. Row a item £ sorted b total £ sum of h-P (sorted) H-P x a = B all good Column 1-200 some headings but overall so I need H1 - H200 column H x A But for the...
6. ### Formula One Halo - Good or Bad?

Formula 1 votes against Halo in 2017 - http://www.skysports.com/f1/news/12433/10515016/formula-1-votes-against-halo-in-2017 Not as cool as the auroscreen or whatever the other option was. But that failed FIA tests apparently.
7. ### Generator formula

Hi everyone, I am looking to know the formula for KW to Kva and any other related formula that you would know thanks v
8. M

### Parallel cables

Hi I was give this calculation to do! First have I done it right? And is this the same as calculating parallel circuits? In a 230V DB 7 different circuit give out an installation resistance test of 200, 200, 150,100,50, 25 and 2. I came up with RT= r1+r2+r3+r4+r5+r6+r7 RT = 1/200 + 1/200 +...
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### Voltage drop question

Hi everybody. I have a question (still learning, passed 17th edition and part P, but I'm not yet registered). If you use formula from On-Site Guide p.140 what the design current you put in the formula, to calculate max length of cable for 11.5V. If 32amp then the maximum length of ring final...
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### high Zs on 110v

hi all, In a bit of a pickle ,got niceic audit imminent ,and i have some exccesive readings from a 110v transformer backed up by 60898 type c 16amps mcb acording to BS7671 pg 61 41.6 max is 0.34 .can change to a type B to get max 0.69. these reading s are from another tester ,who...
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### Industrial How can i select my Generator size and as well as its kVA.............?

HI, all let say.... i have connected load 20,000W = 20kW... I calculate ampere from this formula p=vi(1.732)(0.8) by the help of this formula i got my breaker size...... but i confuse that how would i get my generator size.......? plz help me about that.... thanks advance.......:tounge_smile:
12. D

### String fuses

Hi all, Just running through the "Photovoltaics in buildings guide - 2nd edition", as you do, and can't get my head around the string cable requirements. p 16, 2.1.5 says: "For a system of N parallel connected strings, with each formed of M series of connected modules, string cables are to...
13. T

Hi, i am confused about how voltage drop is worked out and need an answer for the following please; Work out cable size and cpc size you need when you have: Cable length = 50 metres Ib = 32Amps to get a voltage drop that complies with regs i.e. below 5%(11.5 Volts). It's wired in singles and...
14. F

### volt drop?

hi im struggling with volt drop , the circuit is 6mm 2core swa , run under ground , 220M long ,supplying a transformer charging batterys for a gate system rated at 5A. Can anyone help me and give me the formula for the calculation? Thanks:confused:
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### Can you work this out

what is the maximum permitted voltage drop of a cable supplied from 400v three phase. a.11.5v b.6.9v c.20v d.12v I know the answers c but I dont know what the formula is to get there. does anyone know
16. E

### formula for working out ring main cable sizes

Hi Can anybody remember the formula for working out ring main cable sizes (Cable Capacities). I know we use 32amp MCB with 2 x 2.5mm² but its been so long I cant remember the formula that proves 2.5mm² is capable of carrying a ring main load. Thank you in advance Sorry if this has been...
17. ### Volts drop

How do, can any one help me with how to work out volts drop, what is the formula? thanks