Are Electrical Engineers qualified persons?

[cuba_pete]

I had an EE come in to design and spec some MV power factorcaps and reactors one time. This wasbefore arc flash but we did have safety procedures for shutting down andworking on the system. My guys had opened loads and shutdown the substation, soafter all the lights went out we heard a loud G d D m it, and saw the EE on thefloor. He saw us pull the main and check with hot stick, but he did not waitfor us to discharge the capacitance in the wires between the switches. And thiswas the guy that was hired to SHOW US.

I had a qualified supervisor try to discharge the caps on a powered device.

We were in the adjacent room and heard a slight scream and a big thump on the wall. Luckily they were behind a piece of gear and the wall was only about 3 feet away.

The shorting probe probably save their life after giving its own.

 

[gadfly56]

I had a qualified supervisor try to discharge the caps on a powered device.

We were in the adjacent room and heard a slight scream and a big thump on the wall. Luckily they were behind a piece of gear and the wall was only about 3 feet away.

The shorting probe probably save their life after giving its own.

My intimate knowledge of this sort of work could be writ large on the head of a very small pin, but wouldn't you want to discharge through a load bank or something to control the rate of energy dissipation? Not to mention keeping things from going "bang!".

 

[drcampbell]

My intimate knowledge of this sort of work could be writ large on the head of a very small pin ...

Ohm's Law is still applicable. And the internal resistance of power-factor-correction capacitors is quite low.

 

[gadfly56]

Ohm's Law is still applicable. And the internal resistance of power-factor-correction capacitors is quite low.

It's not the internal resistance that's the issue, but the external. The time constant is RC and describes how long it takes to charge or discharge a capacitor to a given voltage. Low R, discharge fast(er). High R, discharge slow(er).

 

[drcampbell]

The sum of internal & external resistances determines how much current will flow. Using the aforementioned shorting probe, the internal resistance was probably the limiting factor.

... The shorting probe probably [saved] their life after giving its own.

 

[cuba_pete]

I use bleed down resistors in my projects with large capacitor banks, but that's my stuff. I also have a shorting probe that I use occasionally.

I suppose it would come down to the cost-benefit ratio. Shorting probes without internal resistance are pretty common and capacitors are generally designed to discharge "instantly".

 

[Dan Frank]

OSHA defines qualified

OSHA defines qualified

So am I:thumbsup:

There is no NEC, NFPA, OSHA, or IEEE definitive standard to determine who is qualified. It is entirely up to the employer to determine if a specific employee has the skills, knowledge, and proper training for a particular task. It is not necessarily a broad general qualification either. Some employees may be qualified for certain tasks and not others. It is task specific.

OSHA 29CFR1910.399 gives the definition of qualified.
Qualified person. One who has received training in and has demonstrated skills and knowledge in the construction and operation of electric equipment and installations and the hazards involved.
Note 1 to the definition of "qualified person:" Whether an employee is considered to be a "qualified person" will depend upon various circumstances in the workplace. For example, it is possible and, in fact, likely for an individual to be considered "qualified" with regard to certain equipment in the workplace, but "unqualified" as to other equipment. (See 1910.332(b)(3) for training requirements that specifically apply to qualified persons.)
Note 2 to the definition of "qualified person:" An employee who is undergoing on-the-job training and who, in the course of such training, has demonstrated an ability to perform duties safely at his or her level of training and who is under the direct supervision of a qualified person is considered to be a qualified person for the performance of those duties.

Clear as mud.