Imminent Power Failure? Make sure you check your buildings switches regularly.


Clients and Friends,
As you know I’m always promoting preventive maintenance, whether related to CSS inspections, thermography or maintenance of your switch gear. Last month, we were involved in a repair that encompassed a number of these factors. It’s a bit of a cautionary tale that I thought might have some wider interest.
During a routine CSS inspection, the ESA inspector noted that there was quite a bit of heat coming from the main switch at this condominium. He suggested that this be further investigated. The property manger contacted us promptly and we initiated a thermographic inspection of all the electrical services including the main switch.
On the day that the thermographic inspection was taking place, I received a call from the site.
The thermographer was so concerned about the heat within the main 3000 ampere  switch that he did not want me to wait the day or so that would normally be needed to produce the report. Below are the results of the inspection. In his opinion this was a “Priority 1, needing immediate attention”.

I followed up quickly after that with a site visit to determine how best to deal with this situation. While the cause was still not completely clear, it was obvious that the switch itself needed immediate replacement. There was a concern that the switch could fail at any time resulting in a loss of power to this 23 storey high-rise condominium.

A replacement switch was sourced and a quotation was submitted. The property manager and board were able to quickly come to a decision and the parts were ordered.
A day was selected for the replacement. The work required a fair bit of co-ordination between the client, Signature Electric, the local utility and the Electrical Safety Authority.  In the end the replacement went quite well with all players arriving on time and the building was actually back on line in advance of our anticipated time frame.
Now that we can all breathe again, the question is what happened here? While it is tough to be fully certain, a closer examination of the old switch did provide some answers.

In viewing the picture (above left) of the switch that was removed, it certainly appears that the blades are engaged, so what is the problem? In fact, in a switch this size, the engaging of the blades is only the first of two steps. Because the switch is so large, a secondary mechanism engages to pull the blade receivers together to make a tight bond. While it is not immediately obvious, the telltale sign is the fibre bar in the centre. When the switch is fully engaged, this bar will be right up against the bus bars. In this case you can see that it is still partially down.

The picture above-right shows the final installation with the new switch fully and properly engaged.

When a switch is new, all the moving parts are greased to allow for proper movement and engagement. As the switch ages, this grease tends to harden up. If the switch is not exercised for many years, as may be the case for a main switch, it is possible, even likely, that it will not work well when needed. It is quite common for us to open a switch in a main service and find that it will not easily close.

The solution is to initiate a regular program of maintenance for your main service where the switches can be tested, exercised and lubricated on a regular basis. At the same time we can clean all the cubicles. If this type program is not in place for your property please contact me and I will be happy to provide a quotation.

Signature Electric is pleased to have worked hand in hand with this customer to arrive at a successful conclusion with no unplanned outages.