Rubber Insulating Matting Use

[Seguridad]

Hi All,

I would like to know if anybody can help me find some reference documents (codes, standards, etc) about the use of insulating rubber mats.

I have an idea about when to place a mat in front of electrical equipment, but I do not find any standard that tells me when to do so. If I need to justify the placing of matting, I what can I base my decision?

Thanks!

 

[zog]

You wont find much, rubber matting cant be considered to provide protection because if any part of the body is touching something else the matting provides no protection, think of it like rubber soled shoes (Or better yet EH rated shoes) , they usually protect you from shock hazards but cannot be considered your primary means of shock protection.

 

[bphgravity]

Have you reviewed the NFPA 77 - Recommended Practice on Static Electricity? I believe it discusses rubber mat use. The NFPA 70E also has provisions regarding insulating mats in conjunction with OSHA requirements.

Also see 250.174(C), 430.133, 525.20(G) and 640.45 of the NEC.

 

[zog]

Of course I have seen those, but I stand by my point that they cannot be relied on for shock protection, are you trying to say otherwise?

 

[Seguridad]

Insulating Matting and Shock

Insulating Matting and Shock

Thanks bphgravity, I will look into those documents and come back with any further findings. Zog, I believe he was responding to my request.

I agree with you two that insulating matting is a secondary protection, and consider that in an industrial environment the primary shock protection should be gloves and then shoes.

Insulating Safety Devices
Gloves + Shoes + Matting = Shock Protection

 

[bphgravity]

I wasn't responding to you ZOG. We posted at nearly the same time.

 

[zog]

Gothcha, sorry.

 

[Seguridad]

Some research on those documents...conclussions

Some research on those documents...conclussions

Hi bphgravity,

I looked into the referenced documents; NFPA 77 does not seem to have any information on this matter, at least not in the particular subject of personal (ground) protection from shock or electrocution. NEC has two articles about insulating matting, these are 250.174(C), 640.45:

Articles transcribed from NFPA 70 2005 (NEC 2005). Published by National Fire Protection Association.

250.174 (C) On Live-Front Switchboards. Instruments, meters, and relays (whether operated from current and potential transformers or connected directly in the circuit) on switchboards having exposed live parts on the front of panels shall not have their cases grounded. Mats of insulating rubber or other suitable floor insulation shall be provided for the operator where the voltage to ground exceeds 150.

430.233 Guards for Attendants. Where live parts of motors or controllers operating at over 150 volts to ground are guarded against accidental contact only by location as specified in 430.232, and where adjustment or other attendance may be necessary during the operation of the apparatus, suitable insulating mats or platforms shall be provided so that the attendant cannot readily touch live parts unless standing on the mats or platforms.

The 430.233 has to do with protection of wiring, it says something like: so as not to present a tripping hazard they should be covered with a non conductive mat (different than an insulating mat).

NFPA 70E has three articles where matting is mentioned: Article 250, where they are mentioned as electrical safety equipment and having to be maintained in a safe work condition. Article 420.10 Guards for Attendants, identical to NEC 430.233. Annex L, Typical Application of Safeguards in the Cell Line Working Zone.

It seems there is not much official information or standards about this matter, let me give my personal point on this matter after some research done in the past days, please tell me know if I am right, wrong, any suggestions, commentaries?thanks.

As far as I can see from common sense and electrical safety knowledge, insulating matting should be used to prevent electric shock or electrocution from grounding by workers in contact with energized equipment. Therefore, matting should be placed in front of all electrical equipment operating at over 50 volts, where workers may be in contact with a live part or exposed energized equipment. In closed facilities (under roof) those could be permanent mats and outside (open air) facilities or equipment we could use removable matting.

I mentioned 50 volts instead of 150 V as NEC says, because at 50 volts you start getting some current that could be hazardous for a person. Anyway in an industrial facility we have higher voltages, but I think it should be well noted.