Earthing of Metal Cable Glands

From my understanding, as per IECEX put simply, for unarmoured or screened cables bond metallic glands to metal box using metal nut for clearance holes, for armoured or screened cables bond metallic glands to metal box using metal nut and lock washer. Use earth tags if the enclosure is non-metallic or armour or screen fault current exceeds what the metal enclosure can handle (or if in doubt).

Local site regulations and requirements may require something slightly different. Not sure about IEEE requirements or US standards requirements.

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Thank you all , but concerning the iecex , can you tell me what iec code number stated this information ?

If you don't know you should NOT be on this job!

The IEC 60079 series. Like most standards, it is a safety document, not a design tool. As one manufacturer's installation instructions state, "...The addition of an Earth Tag will depend upon the earth continuity provision of the enclosures installed...", something only you can determine by contacting your suppliers.

Pick up the phone now, or pick up the cost of the explosion damages later.

Dear sir , Thank u so much for your time , also I would like to highlight that I understand that the manufacturer can make a provision for me to connect the gland grounding jumper ( tag ) or not , But my question is whether the standards itself stated clearly whether that I shall use this provision of the enclosure supplier or not ? As what I know is that I shall connect the gland to the enclosure by a copper jumper to ensure equipotential on both different materials ( gland and enclosure ) but I heard that there is a code stating that if the threads are contacted in more than 1 cm between the gland and the enclosure then no need to install and connect an earth tag . So which is the correct saying ? Thanks again

Just to clarify the thread contact provision......that would require a conductive enclosure that is 1cm thick? The thread on the gland may be too short to accept the nut unless the enclosure hole is threaded, eg a metallic socket cast or welded to the enclosure.

We are drawing pictures with words here..

"...but I heard...", then you should go back to to where you heard it. You have essentially shut yourself out of any real help here because you are refusing to accept an answer that is not to your liking.

Here's how the Forensic Engineer from the insurance company writes his report during the explosion investigation: "...It was noted that Earth Tags intended to ensure the grounding integrity of the entire system, were NOT installed as recommended by the cable gland manufacturer and/or directed in the owner's design specifications. Although it may not be a causative factor, it is quite possible that the missing Earth Tags contributed to the conditions that lead to the overall failure of the explosion-proof equipment to perform its intended duty...". Been there, done that. Is that how you want me to write my report?

btw- bad-mouthing other members of the forum hardly scores you any points around here.

but I heard that there is a code stating that if the threads are contacted in more than 1 cm between the gland and the enclosure then no need to install and connect an earth tag

Would this happen to be relating specifically to Ex d flame proof housings?

Your company should have standard procedures for this. I'd find a better employer if I were you.

Maybe it's not the employer?

Please spare me of your opinion as I am quite sure that you don't understand the question in the first place or all " the other than your's " respectfull answers . Thanks

Gladly.

In my opinion, NEC and BS7671 -or BS7430- required grounding of metallic parts which are not -usually-energized but could be in a ground fault case. Then, this equipment grounding could be a wire [PE- for instance-according to BS or IEC],a conduit, a cable metallic armor and so on. If the gland is connected within the chain of equipment grounding you could use it-using jumpers-in order to complete the equipment ground. If there is not entering cable metallic exposed sheath[armor, lead sheath etc.] or a jumper to be connected you don't need to ground the gland[in my opinion].A grounding gland has to be in contact with the equipment metallic enclosure and has to be connected to ground through it.

You may consult these documents also:

IEC 60079-0 Clause 15 Connection facilities for earthing or bonding conductors. 15.1.2 External. 15.3 Size of conductor connection.

http://www.cooperindustries.com/content/dam/public/crousehinds/industrial-products/catalog-pdfs/fittings/ade4f-datasheet.pdf

NEC 2014 Art.501.30 Grounding and Bonding, Class I, Divisions 1 and 2.

Art.250.4, 250.8, 250.100, 250.102-mainly.

However, there is not a standard requiring to connect this gland with a grounding electrode.

You may or have not. This is connected with the entire grounding system. You have to be an electrical engineer which has experience in electrical installation.

For instance if the supply system is grounded you have to provide a grounding conductor in the internal part-cable, conduit and so on-in order to connect together all [not live] metallic parts and to the electrical supply source in order establishes an effective ground fault path[NEC Art.250]. This conductor has to withstand the maximum short-circuit current.

The gland grounding it is required in order to achieve a potential equalization. See

[for instance] IEC 60079-14 ch.6.3 Potential equalization.

"Potential equalization is required for installations in hazardous areas. For TN, TT and IT systems, all exposed and extraneous conductive parts shall be connected to the equipotential bonding system. The bonding system may include protective conductors, metal conduits, metal cable sheaths, steel wire armoring and metallic parts of structures, but shall not include neutral conductors."

A qualified local Electrician can answer this question.

BS7671, among other applicable national and international electrical standards, refers to metal parts that are part of the installation and are not live, though they could become live under fault conditions. When one considers the risks:

• getting an electric shock from the metal part under fault conditions
• getting an uncontrolled spark that is an ignition source under fault conditions - especially in an <...oil and gas field...> where the presence of flammable gas/air mixtures being present becomes a possiblility

the need to <...earth the cable glands...> in some way becomes glaringly obvious.

So it is rather worrying that this question is being asked.