Free notes
Table A1, and the cooker worked throughWhy add five amps for a cooker socket?
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Table A1 — assumed demand
Everything starts with the design current, from the power triangle:
Same formula you already know as I = P/V. In a design it is called Ib, the design current.
Table A1 then tells you what to assume for each kind of point. For a household cooker the sum is the one On-Site Guide · Table A2 · p.151 prints: 10 A, plus 30% of the full load in excess of 10 A, plus 5 A if a socket-outlet is built into the control unit. Table A1 gives the same result.
The cooker, worked through
A 5.5 kW cooker on a 230 V supply, with a socket outlet in the control unit.
| Step | Working | Result |
|---|---|---|
| Design current | 5500 ÷ 230 | 23.91 A |
| Take the first 10 A | 23.91 − 10 | 13.91 A |
| 30% of the load in excess of 10 A | 13.91 × 0.3 | 4.17 A |
| Add the 10 A back | 10 + 4.17 | 14.17 A |
| Socket in the control unit | + 5 | 19.17 A |
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- Building Regs
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- Fundamental Inspection & Testing
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