Switchboard Lockout Provision

[jnpcook]

I have been asked by my companies Director of Customer Service to research the NEC concerning the following situation.

One of our field engineers was sent to a customers plant to replace the main disconnecting means (molded case switch)on an induction heating power supply. This main disconnecting means was fed from wires coming from an upstream switchboard containing several switches and/or manually operated circuit breakers that supplied power to other machines, etc. The switch that provided power to the induction heating power supply was shut off but apparently there was no provision on the switch for locking it in the off position. A piece of tape was placed over the switch by the customer when they shut off the switch and our field engineer was informed that the switch was shut off and it was now safe to replace the molded case switch in the induction heating power supply. Our field engineer tried to explain that this was not a safe practice and the customer insisted that he continue with the repair.

I have read NEC section 408 in it's entirety as well as the referred to sections in 408.2 (Articles 240, 250, 312, 314, 404) but do not find anything stating that a switch in a switchboard must have a provision of being lockable in the off position.

I have also read NFPA 79 and specifically section 7 covers Supply circuit disconnecting means. Article 7.10.3 states "The operating handle shall be capable of being locked only in the open (off) position." Is your interpretation of this that this applies to the switchboard containing the switch supplying power to our induction heating power supply and that the switch in the switchgear must be able to be locked out in the off position?

I have also read OSHA standards 1910.147 regarding the control of hazardous energy (lockout/tagout) and it seems to indicate that it is permissible to use a tagout procedure instead of a lockout procedure if the energy isolating device is not capable of being locked out (1910.147(c)(2)(i). Also is states that after January 2, 1990 when a repair or replacement is done to a machine or equipment the energy isolating devices that are installed shall be designed to accept a lockout device. 1910.147(c)(2)(iii). I am not sure when the switchgear in question was installed but I was told it did not have provision for a lockout.

Is the scenario described above in violation of code requirements or is this an acceptable method for shutting down a piece of equipment to allow repairs?

Thank you in advance for your help,

John

 

[69boss302]

Re: Switchboard Lockout Provision

It is not a violation of code. Happens all the time in older plants. They do make devices that are capable of covering the switches (depending on the type of switch) that can be locked. I have been known to go as far as removing the leads from the incoming line of the machine I am working on and tapping them up, or even at the breaker or switch depending on the safety aspect. The way I look at it, it's my fingers in there, my life on the line, I don't trust anybody anymore (been bit by people actually ripping off tags and turning things on). I'm going to do what makes me safe. If I have to worry about turning the thing on then I can't concentrate on my work and will end up making a mistake.

Here's one site that has some of these lock out defices http://www.aplussafety.net/products/index.cfm?d=3053&c=4568&p=16518&do=detail

Edit: to add link

[ July 07, 2005, 10:34 AM: Message edited by: 69boss302 ]

 

[friebel]

Re: Switchboard Lockout Provision

I do agree with 69boss302, I worked for the DuPont company for many years, and DuPont has a great Safety Record, and I was always proud of that.
If we had a switch that we could not lock out. We would disconnect the wires and tape them and also put a Tag on the wires.
On our plant our lighting and control panels were Square-D QO Panels. Square-D, makes a locking device that can be install on their QO Breakers. We installed a lockout device on every QO Breaker on our plant, and I am talking about a plant at that time that had 8000 employees. So you can imagine I am talking about a lot of Panels.

 

[jwelectric]

Re: Switchboard Lockout Provision

OSHA rule 1910.147 adopted into law in 1989 and is the rule that you might be looking for.

Go to www.osha.gov and enter 1910.147 in the search box and it will take you to this rule.

 

[jnpcook]

Re: Switchboard Lockout Provision

Thanks. Yes I did already find and read OSHA rule 1910.147 in it's entirety and from this concluded that it does not appear to be an OSHA violation if a proper tagout was used (not sure what was actually used to indicate the switch was in the off position but the director of customer service told me they just placed tape across it which I would venture to say does not meet the proper definition of a tagout).

But NFPA 79 (section 7.10.3) seemed to indicate that it was required for the switch to be lockable in the off position which seems to contradict somewhat the OSHA requirement which allows older equipment without the locking provision.

And I could not find anything in the NEC stating that the swith must have the locking provision on it.

The director of customer service at my plant wanted me to check if this scenario was a violation of safety requirements or codes but from my understanding of the code and from your replies, I do not see that this is the case.

John

 

[rbalex]

Re: Switchboard Lockout Provision

"A piece of tape ... placed over the switch by the customer..." is neither adequate nor acceptable - even if lockout is unavailable.

As an absolute minimum see: 1910.147(c)(5)(ii)(C)(1) and following:

1910.147(c)(5)(ii)(C)(2)
Tagout devices. Tagout devices, including their means of attachment, shall be substantial enough to prevent inadvertent or accidental removal. Tagout device attachment means shall be of a non-reusable type, attachable by hand, self-locking, and non-releasable with a minimum unlocking strength of no less than 50 pounds and having the general design and basic characteristics of being at least equivalent to a one-piece, all environment-tolerant nylon cable tie.

1910.147(c)(5)(ii)(D)
Identifiable. Lockout devices and tagout devices shall indicate the identity of the employee applying the device(s).

1910.147(c)(5)(iii)
Tagout devices shall warn against hazardous conditions if the machine or equipment is energized and shall include a legend such as the following: Do Not Start. Do Not Open. Do Not Close. Do Not Energize. Do Not Operate .

Your Director is wise and needs to know that it is your company's responsibility NOT your customer's for the safety of the employee and must communicate that to the customer.

 

[jnpcook]

Re: Switchboard Lockout Provision

Thanks Bob. I agree with you. I did read that section in the OSHA rules and from my understanding of the situation the tape did not meet the tagout requirements. I have not seen the installation first hand so I was not 100% sure what it looked like when power was shut off at the switch. I will forward this information to the director of customer service. Thank you all for your help. I will continue to check this post in case there is any further discussion.

John

 

[jim dungar]

Re: Switchboard Lockout Provision

Electrical safety during operation and/or maintenace is not a pervue of the NEC. The NEC is for installation, 90.1(B), 90.2(A). The NEC contains requirements that will allow operations and maintenance to be performed in a safe manner. NFPA70E is the "Standard for Electrical Safety in the Workplace". NFPA70E protects employees while they are working. NFPA70B is the "Recommended Practice for Electrical Equipment Maintenance".

In any case a Tagout procedure is as acceptable as a Lockout one. The keyword is "procedure", it must be documented and controlled.

A simple piece of tape over a breaker or switch handle is not acceptable for lockout/tagout. According to NFPA 70E 120.2(D)(4)(c) the tag attachment device will be equal to a "nylon cable tie".

 

[LarryFine]

Re: Switchboard Lockout Provision

John, I'd like to throw in my own thoughts. In addition to the above posts, all excellent, I would suggest some (almost) foolproof isolation steps:

I would throw the unlockable switch at the switchboard, test for voltage between each phase and ground, and between each phase pair, just to be sure.

Then I would disconnect the load-side wires, tape them, and then make the above voltage tests at the load end of the feeder, to be sure you got the right circuit.

Now, as long as you can work faster than it would take someone to find and reconnect the wires in the switchboard, you should be safe against "outside influences".

When doing new work, I used to think leaving breakers off was enough protection when trimming out or connecting new equipment, then I got zapped.

I had the panel cover and breaker handle tagged. Problem? They were in English. Now I don't even terminate the wires until the circuit is completely finished.