Practical electrical design articles: earthing, protection, cables, SPDs, generators, boards and drawings.
What the RCD type letters mean, a one-table guide to choosing AC, A, F or B, sensitivity and type S, and why a type B circuit must never sit behind a type A RCD.
RCD Types AC, A, F and B: Which One Where Read More »
How to read the two IP digits, a location-by-location table of typical minimum ratings, and five site tips on cleaning, glands, cable entry, heat and IK.
IP Ratings Explained: Choosing IP44, IP54, IP65 on Site Read More »
A side-by-side dictionary of IEC and NEC earthing, grounding and bonding terms, a labelled service-entrance diagram and what the differences mean on a project.
IEC vs NEC: Earthing, Grounding and Bonding Terms Compared Read More »
Size a standby generator from the running load, then check the largest motor start; a worked example shows how a soft starter saves about 300 kVA of generator.
Standby Generator Sizing: A Quick Method That Works Read More »
The fall-of-potential method step by step: where to drive the probes, why 62 %, how to check the plateau and how to judge the result for TT, LPS and substation earths.
How to Measure Earth Electrode Resistance (Fall-of-Potential) Read More »
Two quick methods for tray width (sum of diameters and area fill), a worked riser example, and the grouping factors and spans that make a tray schedule hold up.
Cable Tray Sizing: Fill, Spacing and Derating in Practice Read More »
How to measure phase unbalance on a distribution board, why boards drift out of balance, and a minimal-change method that fixes most panels with one or two swaps.
Phase Balancing in Panel Schedules: Measure and Fix Unbalance Read More »
Five checks for choosing an MCB, from rating and curve to breaking capacity, and what discrimination between MCBs can and cannot achieve, with a worked example.
MCB Selection and Discrimination: A Practical Design Guide Read More »
What TN-S, TN-C-S, TT and IT earthing mean for fault current and protective devices, with the same circuit worked through on TN-C-S and TT.
TN-S vs TN-C-S vs TT Earthing: Systems Explained (Plus IT) Read More »
How to size a cable for both current capacity and voltage drop using mV/A/m values, with typical limits and a worked sub-main plus final-circuit example.
Cable Sizing for Voltage Drop: Formula, Limits and Worked Example Read More »