- Location
- Lockport, IL
- Occupation
- Semi-Retired Electrical Engineer
Re: The Chicken Switch
How about keeping it simple, like "remote operator"?
How about keeping it simple, like "remote operator"?
The Chicken Switch
- Thread starter bphgravity
- Start date
- Status
bphgravity
Senior Member
- Location
- Florida
Re: The Chicken Switch
How about, "anti-arc blast, 3rd degree burn, 4 months in the hospital, 2 years of physical theropy, lots and lots of wasted money and law suit-preventor switching device."
Has a ring to it!
How about, "anti-arc blast, 3rd degree burn, 4 months in the hospital, 2 years of physical theropy, lots and lots of wasted money and law suit-preventor switching device."
Has a ring to it!
- Location
- Illinois
- Occupation
- retired electrician
Re: The Chicken Switch
zog,
Don
zog,
A related question. If you are in the room, within the arc flash boundry, but not operating any devices, or working on the equipment, is arc flash protection required? I think that it is, but am not sure. Does the arc flash boundry change when the covers or doors are open?
Don
zog
Senior Member
- Location
- Charlotte, NC
Re: The Chicken Switch
Yes, the boundary will change with the doors open, a hinged door should be assumed to be open for the arc flash study, so when you see an arc flash label on the front of a panel or breaker door that is the distance with the door open.
Yes, arc flash protection is still required but the probabillity of one occuring when you are not doing any operations is slim to none.
Yes, the boundary will change with the doors open, a hinged door should be assumed to be open for the arc flash study, so when you see an arc flash label on the front of a panel or breaker door that is the distance with the door open.
ron
Senior Member
- Location
- New York, 40.7514,-73.9925
Re: The Chicken Switch
Don,
I think the answer is .... it depends on you interpretation, or more importantly the interpretation of your employer.
The standards have words similar to:
working on or near energized equipment.
If the janitor is sweeping near energized equipment, where the enclosure of the equipment is properly grounded, is he required to wear PPE?
Don,
I think the answer is .... it depends on you interpretation, or more importantly the interpretation of your employer.
The standards have words similar to:
working on or near energized equipment.
If the janitor is sweeping near energized equipment, where the enclosure of the equipment is properly grounded, is he required to wear PPE?
- Location
- Lockport, IL
- Occupation
- Semi-Retired Electrical Engineer
Re: The Chicken Switch
Don, are you talking about one person being in the room while another person is operating the equipment? Or are you talking about the equipment not being operated by anyone?
Don, are you talking about one person being in the room while another person is operating the equipment? Or are you talking about the equipment not being operated by anyone?
- Location
- Illinois
- Occupation
- retired electrician
Re: The Chicken Switch
Charlie,
I am talking about just being in the room within the arc flash boundary with no one working on anything. It is my understanding that arc flash PPE is required anytime you are within the arc flash boundary.
Don
Charlie,
I am talking about just being in the room within the arc flash boundary with no one working on anything. It is my understanding that arc flash PPE is required anytime you are within the arc flash boundary.
Don
rcwilson
Senior Member
- Location
- Redmond, WA
Re: The Chicken Switch
Don - That is our company's interpretation also. The arc flash hazard exists whether the door or covers are open or closed, at least according to our interpretation of 70E.
At one facility we have certified, arc-proof 5 kV switchgear that will contain the arc blast inside the gear. But the arc flash calculations still come up with an arc flash boundary of 31.8 meters, over a 100 feet, which means no one should be allowed in the switchgear room unless the gear is de-energized. (83 cal/cm2 flash hazard @ 18").
This does not make sense but it falls out from a rigid interpretation of NFPA 70E.
We purchased several of the Chicken Switches for use by our commissioning electrician?s and operators. It allows them to get out of the blast zone, especially for that first time that the gear is energized.
But for normal operations, I think there has to be some judgment applied. Does it make sense to require a full level 4 PPE to walk past the switchgear? Or should that criterion only apply if any door is open or any switching is occurring? We already restrict the electrical rooms to only ?qualified? personnel. I compare the electrical risks to other risks in our plants. If one of the high-pressure steam lines develops a leak when I am walking by, I will be sliced in half and die. How great is the risk of a steam injury compared to me being injured reading a meter mounted on the front of the switchgear?
From a design perspective, we now try to locate all of the breaker controls and metering away from the gear, to minimize the number of times an operator has to be exposed in the blast zone. We no longer put MCC?s near operator control stations for the same reason.
This arc flash seems to be full of magic numbers and engineering judgments, but by paying attention to it we are making safer work places.
Don - That is our company's interpretation also. The arc flash hazard exists whether the door or covers are open or closed, at least according to our interpretation of 70E.
At one facility we have certified, arc-proof 5 kV switchgear that will contain the arc blast inside the gear. But the arc flash calculations still come up with an arc flash boundary of 31.8 meters, over a 100 feet, which means no one should be allowed in the switchgear room unless the gear is de-energized. (83 cal/cm2 flash hazard @ 18").
This does not make sense but it falls out from a rigid interpretation of NFPA 70E.
We purchased several of the Chicken Switches for use by our commissioning electrician?s and operators. It allows them to get out of the blast zone, especially for that first time that the gear is energized.
But for normal operations, I think there has to be some judgment applied. Does it make sense to require a full level 4 PPE to walk past the switchgear? Or should that criterion only apply if any door is open or any switching is occurring? We already restrict the electrical rooms to only ?qualified? personnel. I compare the electrical risks to other risks in our plants. If one of the high-pressure steam lines develops a leak when I am walking by, I will be sliced in half and die. How great is the risk of a steam injury compared to me being injured reading a meter mounted on the front of the switchgear?
From a design perspective, we now try to locate all of the breaker controls and metering away from the gear, to minimize the number of times an operator has to be exposed in the blast zone. We no longer put MCC?s near operator control stations for the same reason.
This arc flash seems to be full of magic numbers and engineering judgments, but by paying attention to it we are making safer work places.
zog
Senior Member
- Location
- Charlotte, NC
Re: The Chicken Switch
Bob,
I am curious about the system you described with the 100 ft arc flash boundary, can you give any details?
Bob,
I am curious about the system you described with the 100 ft arc flash boundary, can you give any details?
Re: The Chicken Switch
Flash suits protect against just that...flashes. They will theoretically protect against heat, ionized gas entering the lungs, and ignition of clothing by superheated metal fragments. They will not do a darn thing to protect you from those same fragments hitting you at ballistic velocities. Kind of like a bullet proof vest, they may not penetrate, but it still feels like you got hit by a train.
Flash suits protect against just that...flashes. They will theoretically protect against heat, ionized gas entering the lungs, and ignition of clothing by superheated metal fragments. They will not do a darn thing to protect you from those same fragments hitting you at ballistic velocities. Kind of like a bullet proof vest, they may not penetrate, but it still feels like you got hit by a train.
- Location
- Illinois
- Occupation
- retired electrician
Re: The Chicken Switch
Matt,
You are correct. I expect that the next edition of 70E (2007) will address that issue. It is very likely that there will be no energized work on any system with an incident energy that exceeds 40 cal/cm^2.
Don
Matt,
You are correct. I expect that the next edition of 70E (2007) will address that issue. It is very likely that there will be no energized work on any system with an incident energy that exceeds 40 cal/cm^2.
Don
zog
Senior Member
- Location
- Charlotte, NC
Re: The Chicken Switch
This requirement already is in the 2004 standard.
- Location
- Illinois
- Occupation
- retired electrician
Re: The Chicken Switch
Zog,
I missed that. Can you cite the section for me? Thanks.
Don
Zog,
I missed that. Can you cite the section for me? Thanks.
Don
zog
Senior Member
- Location
- Charlotte, NC
Re: The Chicken Switch
My bad, it is in the 70E handbook, not the standard. Article 130.7
My bad, it is in the 70E handbook, not the standard. Article 130.7
- Status