Industrial electrical installations

Three phase distribution and machinery connections

Industrial sites run on three phase for straightforward reasons. The same power arrives down smaller conductors, motors start and run better on it, and the load spreads across the supply instead of leaning on one leg. Most of what an industrial electrician actually gets called to on a factory floor is not exotic. It is an unbalanced supply, a board extended well past what it was designed for, or a machine connected by whoever delivered it and not by an electrician.

Connecting plant properly means starting at the incomer and working outwards. Cable sized for the real duty and the run length, discrimination arranged so a fault on one machine does not drop the whole line, local isolation you can lock off, and a schedule that tells the next person what feeds what. Where the environment is wet, dusty or washed down at the end of a shift, ingress protection and the right glands belong in the specification, because stainless costs less than a rewire in two years.

Motor control and the cost of nuisance tripping

Motors are where industrial installations get interesting. Direct on line starting is simple and hard on both the mechanics and the supply. Star delta or a soft starter takes the edge off the inrush current. A variable speed drive does more again, giving controllable speed and a real energy reduction on fans and pumps that spend their lives throttled. Drives also bring harmonics and screened cabling requirements, so they get specified deliberately and not simply fitted where the old starter was.

Protection has to suit the machine and not whatever device happened to be in the board. Correct overload settings, phase failure and single phasing detection, and properly sized contactors are what stop a stalled motor becoming a burnt out winding and a week of lost output. Where a line is critical it is worth agreeing which spares live on site, because the delay after a failure is almost never the labour, it is waiting for a part.

Shutdown planning on a working site

Nothing on an industrial job costs what the downtime costs. Two hours of isolation on a packing line can be worth more than the entire quote, so the shutdown gets planned as carefully as the installation itself. That means a written sequence, agreed permits and points of isolation, the right locks and warning notices, and proving dead every single time instead of trusting a label somebody wrote in biro years ago.

Most of the work can be prepared while the site keeps running. Containment, cable pulls, new boards and terminations can all be taken to the point where the changeover itself is short, so the actual break in production is measured in hours and not days. Where a site has a genuine shutdown week, that is the moment for the big items. Tell us when yours falls and we will work backwards from it.