As an old engineering colleague of mine, wryly remarked to me recently - engineering and technical graduates are often like babes in the wood when newly on-site as their practical and safety knowledge is almost non-existent. Despite an intensive 4 year (or longer) study program. My retort was that it didn't only apply to young engineers and technicians - and that "common sense is not so common around here" is often an appropriate expression on-site for even old hands. As we all know, electricity (well, energy) is extremely dangerous and can kill or maim if you are even a little careless. Fortunately most acts of carelessness result in a mild jolt (or electric shock), leaving no permanent physical reminder of the incident; but the unfortunate get life-long scars or worse.
We are compiling a list of tips from yourselves on working safely when commissioning a plant or with machinery from an electrical, mechanical, instrumentation and IT point of view. Please feel free to respond to this email with any safety and commissioning tips (a one liner to a complete procedure is fine) and we will circulate them to everyone in a nicely put together electronic book - over the next week or so. As we did with the software where we had a great response thanks to you, our wonderfully supportive global community of engineers and techies.
Examples of tips (do you agree with them all or not ?) from different parts of the world include: (and I would love you all to contribute) are (and thanks to Vijay, our experienced senior Electrical Engineer, for many of these initial ones below):
- * Watch out when taking measurements with your Fluke - don't think you can connect directly onto the bus bar to measure voltage
* Make sure the cabinet has been clearly tagged and locked out before commencing work
* Before going for a black start for a power station make sure there will still be auxiliary power for the stand-by generator
* Make sure you have sufficient spare fuses
* Make sure you have adequate lighting at night when troubleshooting a cabinet
* When opening the electrical cabinet, make sure the door doesn't close on you inadvertently when you are taking measurements.
* If you are going to work on an electrical panel, ensure that it is disconnected from ALL electrical sources. Visible contact separation and locking against re-energisation are a minimum check. Ensure that earthing/grounding is firmly in place until your work is completed.
* Never assume that a part is dead unless it is visibly earthed.
* When you earth/ground a bus or conductor, ensure that there is no voltage using an appropriate test method. If you are using a removable earth clamp, connect the earth clamp first to the earth bar and then lightly touch one of the other clamps (normally there are three other clamps one for each phase) on each phase conductor. If there is no spark, then go ahead and connect the clamp .
* If you have ensured that everything is disconnected and still are unsure and want to ensure that an LV bus or terminal is dead; do so by touching the part in question with the back of your fingers with the palm open and facing you. If the part is live, the shock causes the fingers to curl and the arm to move towards the body (both are involuntary reflex actions), thus breaking the contact. Touching in any other way can be fatal.
* Live working (work on parts which are normally live) is permitted in rare cases. All other work must be done after isolation and earthing only.
* Sometimes you may have to check for voltage presence or measure the voltage under live conditions. If you are testing the voltage with respect to earth, place or connect the earth side measurement lead on the earth bus first and then place the other (usually RED) lead on the live part. Many people have received inadvertent electric shocks by reversing this procedure.
* Do not use uninsulated test-leads or tools with bare shanks when working on panels where live parts can be present. There is always a possibility of accidental short circuits.
* When you finish working on any equipment, ensure that no tools or operating handles remain on the live parts. They can cause short-circuits unexpectedly and can injure or kill you or someone else when the equipment is racked in or switched on.
* If you are called upon to work on or inside equipment driven by electricity, ensure that all procedures for safe isolation of electric supply to the equipment have been completed and power cannot be turned on unless you have done your job and move away from the equipment. Insist on a lockable safety device and ensure that the key is in your possession.
* Do not take any short cuts, especially when you are the person in-charge of a crew which is carrying out the work. Before you allow the equipment to be re-energised, ensure that everyone is in a safe location away from the equipment. Do not resort to any last minute tweaking after you return a work permit.
- Instrumentation and Electronics
- * Make sure you don’t inadvertently put the PLC into run mode
and we also need heaps of tips on mechanical and IT
* Assume the software is not working until it has been tested
Yours in engineering learning