Arc Flash Protection and Equipment

Kinky! Rubber gloves with leather gloves over them. Gossamer thin rubber with kid leather, what a combination, I'm going weak at the knees.

OK I'll try to be serious. Wearing of PPE regulations are open to interpretation when the practicality of a task is taken in to consideration.

To bad they're not thin and kid leather. The rubber is thicker than heavy duty cleaning gloves and the leather is somewhere between shoe leather and seats in your car.

I know the ones, last time I was supposed to use them they ended up being thrown across the substation!
I couldn't get them in to were I was working, never mind get hold of anything.

Sigh. Sorry I can't help, but I will watch this thread carefully. I know some safety rules are necessary, but sometimes they get ridiculous. Somewhere between arming a person with a toothpick to fight a dragon, and dressing up like an astronaut to rollout a 2A fuse, lies common sense.

Off rant mode, exit stage left...

Open a jar of Limburger Cheese, instant hazardous atmosphere. Need to...cough..leave...cough gag.....ventilation......wheeeze sniffle......on.

If the panel has power coming into it, then the panel is NOT de-energized. When you turn off the breaker in the panel, all you have done is turned off the breaker in the panel. You have to turn it off at the buss and then recheck it for power and at that point, you are allowed to take off the PPE and treat it as a de-energized. If the panel is not connected to a buss, then it is connected to a breaker box on a wall and that breaker box will have in it a breaker for the machine. After that breaker is turned off and locked out, then you can test the operating panel and if it is de-energized you can take off the PPE and continue as you like. Good Luck and Stay Safe!

Not All Power Supplied to a panel comes from the panel Disconnect in all cases . Since you are preforming a major tranplant to the machine. (Controller replacment) Turn the power off at the supply panel and the Panel discconect. Lock and tag - use a lock box if seven people will be working on the panel. Check and then have second person check the panel for power. This mean all terminals for AC and DC voltages. Remove all the fuses, Make sure the transformers supplied by the panel disconnect have been dengizered. VFDs, DC controller and Servo motor drive have large Caps that can hold high DC voltage +750VDC. Make sure the motors can not be drive by a machine load to act like a generator. (example elevators and long inlcine conveyors). Interfaces to up and down stream equipment the may supply external power. These are just few of the things I would checkout before starting a replacment job. Knowing the equipment and how it operate also helps. Study the schematics for external power supplies. Remeber one wrong move and your toast.

Can you fit a secondary insulator around your main switch in the panel be it clear pespex etc to effectively isolate the still live part of the main switch from the rest of the panel without deratting it or even fit a secondary insulator using the corret ppe after opening the panel . Being from Australia i am not familiar with your rules but i would think that if you provided a physical barrier from live parts and follow it up with the appropriate documantation to explain why this is a practicable solution to allow specialised work to be performed it would be ok.

Typically the energized portion of the main CB can be covered by a lexan or metallic / grounded cover to avoid inadvertent contact with hazardous voltage. The other components that are on the load side of the main CB can then be safely worked on and considered de-energized. If the panel is already in operation then a retrofit kit can be installed covering the incoming line / hazardous voltage. This is typically what is preferred practice in the semiconductor capital equipment business. I believe that this arena is more stringent than the commercial / industrial business so this practice would be acceptable.

Surely there is a breaker upstream of the panel. Why can you not open this breaker and lock it out?

Martin

if there is any voltage detected comming into the panel over 50 volts then it is not dead. can you ground yourself and touch any wire in the machine and not get shocked? something about OSHA, they did go to school and hopefully you did too. lock out the the source feeding the control panel!

Remember, one blunder will get you 6 feet under.

Jonathan

I have heard and seen the results of improper grounding while working in a panel. One man here in Indiana was sent to the hospital last year after he shorted out a bus bar in a main panel. He lived but was badly burned. It burned all of his clothes off of him. Makes me want to put on a Faraday suit. Set up would be rigorous, but you could work on any live circuit. Here is a fascinating video of a faraday suit in action. Absolutely awesome. http://www.youtube.com/watch?v=7nX3SxRrqWA

Common sense would dictate that if the device you are working on has no voltage present,due to locking out of power source, and verified by measurement, then no protection is required to perform repair,replacement of DEENERGIZED components.

The appropriate PPE would be required during deenergizing/reeinergizing of the hazardous voltage supply source.

The local authority having juristiction can require more stringent rules than OSHA,regarding electrical as well as compressed air,steam,flywheel inertia, stored energy,etc.

Check with the LAHJ.

Question - But if I have turned off my breaker and have verified that there is no voltage present past the breaker can I de-rate to a lower level and treat the components as being de-energized even if located in the same panel????????-------------------------------------------------------------------------------------------- NO...PERIOD . If the breaker is in the panel and the feed side is hot, then the panel is NOT de-energized and has to be handeled with (appropriate PPE). You have to disconnect the feed to the main breaker in the cabnet. -------------------------------------------------------------------------------------------------------------- This can be a cord plugged into a outlet, a hardline to a power buss, a hardline to a breaker box on a wall somewhere, or a hardline to a switchgear.------------------------------------------------------------------------------------------------------- Statement - I have Googled and Binged and Whathaveyoud and have not had any results in my querry. Every piece of equipment they have shown or mentioned has a remote disconnect or breaker, but not one contained within the panel. These are large panels usually 6 to 7 feet tall and as wide as ten to 15 feet. They are almost all fingersafe and have guards over the disconnects and fuse connections.------------------------------------------------------------------------------------------------ Answer - The reason they do not mention the breaker in the panel you are working on is because it does not matter. If that breaker has power, so does the panel and you have to keep your PPE "ON" ------------------------------------------------------------------------------------------------------------------------------------------- To be able to remove your PPE, you will have to fine the source of the power and disconnect it there. (remote breaker - remote fuse box - plug on the wall if it is a corded machine - or turning off it off at the power buss.)--------------------------------------------------------------------------------------------------------------- I keep going to the power buss because you insinuate that this is a manufacturing facility. In most facilities, the machine is on the floor, and the power line (conduit or cord) goes up to the ceiling and attaches to a buss box (breaker or fuse box) Some plants do not have buss bars so the go up with hard pipe and over the ceiling and to a breaker box on the wall.---------------------------------------------------------------------------------------------------------------------------------------------- Either way, there is a place to disconnect power to the machine that is not in the machine. After that is shut off and you verify it by wearing your PPE and testing for the voltage in the panel and it show dead, then you can remove your PPE and you can perform your repairs and you will not be dead when your finished with that job.------------------------------------------------------------------------------------------ It is very important that you understand that the breaker in the machine is not for maintenance, it is to protect the machine from itself. (shorts or overloads) If it has power, it can be shorted and that is why you need to treat it with respect. The only way to work on the machine without PPE is to remove the energy at the source. ---------------------------------------------------------------------------------------- Also remember (like one of the other posters said) Electricity is not the only energy source. Air, water, gravity, stored energy like air tank, water tank, spinning parts, and gravity can all get you at any time as well so always verify that all your energy sources are removed and your moving parts are secured before attempting your repair. ----------------------------------------------------------------------------------- I do not know you personally and these statements might seem harsh but I like your arms, hands, and fingers attached to your shoulders so you can have these talks with others over the internet. I also like your brain wet and spongy in your skull instead of cooked or splattered on the wall. ------------------------------------------------------------------------------------------------------------------------------------ Please remember, if any energy is in the panel your working on, always wear the PPE required for the job. I just do it the other way and de-energize everything and I have another person check it before I do any work on the panel I am working on. My life is worth more than the paycheck and my wife like it when I come home every day after work in one piece. ---------------------------------------------------------------------------------------------------------------------------------------------------- Accidents happen but many of them can be avoided. God Bless and Stay Safe!

Have been off for a few days so I haven't gotten back. All our panels dsconnects are covered and protected. They are also finger safe. The only thing that could get into the hole is the tester lead to check for voltage. As previously stated I have all the training through category 4 as well as trainer. I know the rules and how they pertain to voltages and panels and all the other crap. Main feeds for equipment are controlled from our penthouse. These are all conduit down to PP panels. From there they distribute to MSP panels and from there they feed several MSC panels. Turning off one MSC panel will shut down several Motor Control Panels where up to 24 conveyors and associated equipment will be shut down. We never work on circuit breakers live and have multiple equipment for locking out whatever is necessary. OSHA loves us because we are a government entity and one problem in one installation can be used as a stepping stone to larger fines if found in another installation on the other side of the country. With over 40 miles of conveyors and all the panels to control close to 1000 conveyors I was looking for what OSHA refers to as acceptable in reference to one small device being replaced in a control panel with an internal "Protected", "Finger Safe", Circuit breaker (which is turned off). Inside all these panels there are seperate breakers for each motor and associated controls as well as overload modules and removable and locking sections with each Smart Motor Controller to facilitate LO/TO on each one for repairs being made to said equipment. Locking out and tagging one motor is no problem but these main disconnects are not what protects the equipment per-se. They only provide power distribution to the seperate motor controls and breakers and act as a second response to problems within the panel. Ground faults and other problems are detected upstream and usually react faster than these disconnects or the fuses associated with them. Short of locating these disconnects to the outside of the panels I was trying to determine if they could work with only rubber gloves while installing a screw to a device being positioned into place with a starter screwdriver which is "double insulated" without having to (remove leather glove, insert screw into starter, re-apply glove insert screw, repeat, repeat, repeat) when you have already checked for any voltage, are in direct view of said disconnect and are trying to manipulate small tiny little pieces.

Hope I detailed this enough so people can understand exactly what I am referring to. It is not a little machine plugged into a wall or even connected to one breaker. If it was there would be no problem. It is a protected breaker but unfortunately located inside the panel itself.

to sum up

what you are doing is safe, but what you need are some clear regulatory precedences, so you can have a clear easy to use & explain procedures.

Problem is arc flash rules[for lower voltages] being relatively new & the rules haven't been in place all that long, there is not the history either written or in practice amongst the enforcement personnel, leaving you on uncertain ground.

Exactly my predicament! They don't and won't tell you what or how to do any procedure, only what they don't like and how much the fine is.

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Arc Flash

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An Arc Flash is an electrical explosion due to a fault condition or short circuit when either a phase to ground or phase to phase conductor is connected and current flows through the air. You can use electrical safety products including arc flash clothing, arc flash protection kits.