Electrical Safety

An arc flash study calculates how much thermal energy a worker would receive if an arcing fault occurred at a piece of equipment while it was open, and converts that into an approach boundary, a protective clothing requirement and a decision on whether the work should be done energised at all. A HAZOP examines deviation in a process and does not ask that question. The study is built from an impedance model of the distribution system, a short circuit calculation and a protective device coordination study, because incident energy is governed by how long the fault burns as much as by how large it is. Our team runs it to IEEE 1584 across every credible operating configuration, including tie breaker closed and standby generation.

Yes. Periodic electrical safety audit by a competent person is required under the CEA Measures relating to Safety and Electric Supply Regulations 2010 and under the state factory rules made under the Factories Act, and the report is submitted to the inspecting authority. The interval and the reporting format vary by state. Our audit covers the installation from the incoming supply through substations, switchrooms and cable galleries to the point of use, combines clause compliance with thermography, earth resistance and insulation measurement, and ranks findings on consequence and exposure so remedial spend follows the hazard rather than the clause number.

It is calculated, not chosen. IEC 62305 2 works from the local ground flash density, the collection area of the structure, its construction and contents, the occupancy and the consequence of loss, and returns a risk that is compared against a tolerable value. That comparison sets the protection level, and the protection level then fixes the rolling sphere radius, the mesh size, the down conductor spacing and the surge protective device coordination. A system installed without that calculation has no defensible basis, whatever hardware is on the roof. For storage tanks we also apply API RP 545, which covers floating roof shunts, bonding and the vent arrangement.

Because the design was calculated on assumed soil resistivity and has not been checked against reality since. The installed grid sits in ground that may not match the assumption, it corrodes over a decade, and later additions are often earthed locally rather than tied back into the grid. We measure soil resistivity by Wenner array, grid resistance by fall of potential, touch and step potential where the calculation is marginal, and bonding continuity across structures, equipment and cable armour. We then compare what we measure against what the design assumed and against the clearing time your protection actually delivers, since a touch potential that is safe at 200 milliseconds may not be at a slower one.

Classification decides where the zones are. It does not tell you whether the equipment standing in those zones is suitable for them, correctly installed and still compliant, which is a separate assessment under IEC 60079 14 and 17. We check equipment group, temperature class and protection concept against the zone and the material present, verify certification and its conditions, and inspect the detail the protection concept depends on, being flame path condition for flameproof, terminal condition for increased safety and the loop calculation for intrinsic safety. The findings that recur come from ordinary maintenance rather than design, such as a non certified cable gland substitution or an intrinsic safety loop extended without recalculation.

When you handle flammable liquids or combustible powders and ordinary earthing practice does not address the hazard, which is most of the time. Charge is generated by flow, splash filling, pneumatic conveying and plant movement, and whether it ignites depends on the charge relaxation of the material, the geometry of the accumulation and the minimum ignition energy of the atmosphere. We assess the operations where charge is generated, identify the credible discharge types by geometry including brush, propagating brush and bulking discharge, and compare available energy against the minimum ignition energy present. The controls that follow are usually operating limits, bonding arrangements and container selection rather than equipment.

Yes, and both sit in this practice. We deliver the electrical load list, the single line diagrams, the earthing design to IEEE 80 and IS 3043, the lightning protection system to IEC 62305 and the explosion protected equipment selection to IEC 60079, for new build and for retrofit. That design work used to sit inside a multi discipline engineering scope where it received less attention than it needed. Holding it alongside the assessment work means the engineer who calculates what an installed system actually achieves is the one who knows what it was specified to do.

Any change that alters fault current or clearing time. A transformer upgrade, a new incomer, a change of utility fault level, a protection setting change or a new switchboard all change downstream results, and a study that predates the change is describing a network that no longer exists. NFPA 70E expects the study to be reviewed at defined intervals and after significant modification. We state the triggers explicitly in the report and set the review interval, so the revalidation is scheduled rather than discovered after an incident.