Electrical safe working practices. 1

[61900]

Hi,
I would really appreciate anybodies advice on this.
An overload trips protecting Inverter and motor, a fitter attempts to reset the overload twice without success and then calls for the electrical engineer on site. The electrical engineer get's a brief account of what's happened then also attempts to reset the overload. As the overload blows, it welds the contactor shut. He spots this and replaces the contactor, then attempts to reset the overload again. This time it not only welds the contactor shut but trips the main supply breaker (165A) to the Control panel as well.
Now realising it requires further investigation starts to test along the circuit, finding the invertor at fault.
He has now been suspended for unsafe working practices.

Now, as an electrical engineer myself, i agree that after the fitter stating he'd tried to reset the overload twice, it obviously wasn't going to reset a 3rd time and he should have starting testing the circuit immediately but i'm a little confused at how the unsafe working practices comes into it.
Please, any advice would be great.

 

[rbulsara]

Resetting O/L once or twice may be OK. But why would a "fitter" be allowed to "replace a contactor"?. Only a qualified electrician should be doing that.

A proper procedure would have called for seeking electrician's services after a couple of O/L resetting attempts by an operator.


Rafiq Bulsara

http://www.srengineersct.com

 

[dpc]

how the unsafe working practices comes into it

1. Repeatedly attempting to reset an overload device without troubleshooting the actual cause.
2. Replacing parts and attempting a restart without determining root cause, such as testing the motor.
3. Working outside his area of qualifications.
4. Creating possible fire hazards and other safety hazards.
5. Lack of proper PPE (just guessing)



David Castor

http://www.cvoes.com

 

[61900]

Thanks for both replies, unfortunately i've been misunderstood/not explained fully. It was the electrical engineer who has been suspended for apparently knowing better than to attempt to reset the o/l for a 3rd time. The fitter has been disciplined via written warning.

It's the unsafe working practice, understanding the possible hazzards that could occur under fault conditions i appreciate that it was silly to attempt a further reset

i) possible fire hazzard (presumably, if it was an earth fault then i supposed there could be a risk of electrical shock due to indirect contact).

ii)further damage to the circuit involved

iii)Repeatedly attempting to reset an overload device without troubleshooting the actual cause.

iv) Replacing parts and attempting a restart without determining root cause, such as testing the motor.

Would you agree with these points as unsafe/poor working practices.

Thanks again.

 

[dpc]

If an engineer was doing the repair work, he/she was probably definitely working beyond their qualifications!

What was done is roughly the equivalent of replacing a fuse with a copper slug. If a protective device is operating repeatedly, it must be assumed there is problem rather than first assuming there is no problem and testing this theory to destruction.



David Castor

http://www.cvoes.com

 

[61900]

'If an engineer was doing the repair work, he/she was probably definitely working beyond their qualifications'!


Not if he was an electrical engineer as stated. I think the answer to my original question is, he should have known better!

Thanks for your replies.

 

[xnuke]

I agree with dpc as stated.

If an engineer was doing the repair work, he/she was probably definitely working beyond their qualifications!

Most electrical engineers do not know how to do repair work, and most sites will not let engineers handle tools for good reason. When I was a supervising maintenance technician (before I became an engineer), I used to tell my techs that if they saw an engineer walking toward a piece of equipment with a tool to tackle him, and if they saw an engineer walking away from a piece of equipment with a tool to run for their lives. I'm surprised the engineer only got suspended. I would've fired him.

xnuke
"Live and act within the limit of your knowledge and keep expanding it to the limit of your life." Ayn Rand, Atlas Shrugged.
Please see FAQ731-376 for tips on how to make the best use of Eng-Tips.

 

[61900]

In response to xnuke:

The job was to locate an electrical fault on a circuit, i would expect any of the electrical maintenance engineers to be capable of doing this, otherwise there'd not be much point in employing them. He did find the fault eventually but his methods were questionable.

 

[robertjo24]

XNUKE, I have to laugh at your post…kind of makes a point.

There is a distinction between trained, competent, and qualified.

In my company (energy/pipeline), only a qualified electrician can initiate troubleshooting and repair of an electrical circuit. This qualification comes through training (OJT, CBT, etc), and is signed off upon yearly. Our engineers certainly have the knowledge, and all should be competent, but rarely are they “qualified” as per the rules.
It has been hammered into each of our operations personnel who have electrical safety training, that if a safety device trips, they must contact a qualified electrician to investigate the issue. Re-engaging a tripped safety device is grounds for disciplinary action, up to and including termination.

 

[oldfieldguy]

The scenario I read in 61900's original post would have gotten somebody dismissed in many locations.

Assuming you're in the jurisdiction wherein the NFPA 70E code applies, it states that "After a circuit is deenergized by a circuit protective device, the circuit SHALL NOT be manually reeenergized until it has been determined that the equipment and circuit can be safely energized."

If the Code doesn't legally apply, it's still a very good common sense approach to handling protective equipment operations.

In our practice, that determination can be as simple as a quick review of the operating conditions that may have resulted in a mechanical overload, causing the thermal overload (or circuit equivalent) to trip. In this case, we tell the operator he gets one more try. A second "overload trip" means "call an electrician".

We further inform operators that the operation of the motor circuit protector or circuit breaker is not for them to reset under any circumstances. That's a job for the electrical department, and then only after an assessment is made of equipment conditions that may have resulted in the operation.

Fuses are voltage-carrying components and therefore are NOT accessible by non-qualified personnel, i.e., anyone NOT an electrician.

Our engineers don't do any "hands-on" work without the participation of electricians, first because we don't generally have the tools, it not being our job, and second, getting the electricians to actively participate in the thornier troubleshooting extends the skills of the electricians.

old field guy

 

[Zogzog]

OSHA 1910.334 (b)(2) "Reclosing circuits after protective device operation." After a circuit is deenergized
by a circuit protective device, the circuit protective device, the circuit may not
be manually reenergized until it has been determined that the equipment and
circuit can be safely energized. The repetitive manual reclosing of circuit breakers
or reenergizing circuits through replaced fuses is prohibited.

Note: When it can be determined from the design of the circuit and the
overcurrent devices involved that the automatic operation of a device was
caused by an overload rather than a fault condition, no examination of the circuit
or connected equipment is needed before the circuit is reenergized.