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Filling in EIC page 2: supply, earthing and the main switchIs maximum demand the main fuse?
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The question at the end: Is maximum demand the main fuse? The answer is in the notes below.
The notes
Exactly as they are on the site.
This is the general characteristics — what an inspector has to know before inspecting anything. Most of it is ticks.
| Box | What goes in it |
|---|---|
| Earthing arrangement | TN-C, TN-S, TN-C-S (PME), TN-C-S (PNB), TT or IT. On the A4 form, TN-C-S is split into PME and PNB |
| Live conductors | AC or DC, then the wires. Single phase is 1-phase, 2-wire (line and neutral both count). Three phase with a neutral is 3-phase, 4-wire |
| Nominal voltage, frequency | 230 V (or 400/230 V three phase) and 50 Hz. These are by enquiry |
| Prospective fault current, Ze | By enquiry or measurement. Both are live tests — leave them empty until you’ve done them |
| Supply protective device | The DNO’s cut-out fuse, read off the front: e.g. BS 1361, Type II, 100 A |
| Means of earthing | The distributor’s facility, or an installation earth electrode (with its type, location and resistance) |
| Maximum demand | See below |
| Earthing conductor | Material and size, e.g. copper 16 mm². A tick for “connection / continuity verified” comes later |
| Main protective bonding | Material and size, e.g. copper 10 mm², and what it bonds: water, gas, oil, structural steel, lightning protection, other |
| Main switch | Location, BS (EN) number, number of poles, current rating, voltage rating |
Maximum demand isn’t the main fuse
It’s tempting to write the cut-out rating (“it’s a 100 A fuse, so 100 A”) or the main switch rating. Guidance Note 3 says what it actually is: the maximum demand expressed in amps, kW or kVA, after diversity is taken into account. The form says “kVA / A”, so delete whichever you’re not using. The fuse rating already has its own box.
The main switch: isolator or circuit-breaker?
A domestic main switch is normally BS EN 60947-3: a switch-disconnector. The 100 A on the front is what it can switch on load. It doesn’t protect anything. So the form’s “if overcurrent protective device” block is N/A, and so is the “if RCD main switch” block, unless the main switch really is an RCD. A main switch to BS EN 60947-2 is a circuit-breaker, and then its rating and breaking capacity go in that block. Two poles on single phase (line and neutral), more on three phase.
Boxes you leave empty for now
| Box on page 2 | Filled in after |
|---|---|
| Main bonding: continuity verified | Testing continuity of the main bonding |
| Confirmation of supply polarity | The live supply polarity check |
| Prospective fault current · Ze | The live tests at the origin |
| Earthing conductor: continuity verified | A sensible Ze, taken with your lead on the earthing conductor itself, shows the earth path is continuous all the way back to the source |
Guidance Note 3 · 2.3 · required information, max demand Guidance Note 3 · Fig 5.2 · p.148 · an example page 2 BS EN 60947-3 · the main switch
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