GFCI for Welding Machines

This is a pretty sketchy area...I would say that you should have a comprehensive grounding strategy in place that will stand up under scrutiny...If you don't have GFCI protection, then you better be able to show why it's not necessary, that your workers are protected as much as can be reasonably expected in this situation...and that some authority(OSHA) has signed off on it....

"In industrial establishments where conditions of maintenance and supervision ensure that only qualified personnel are involved, an assured equipment grounding conductor program as specified in 527.6(B)(2) is permitted for only those receptacle outlets used to supply equipment that would create a greater hazard if power was interrupted or those that have a design that is not compatible with GFCI protection."

http://ecmweb.com/code-basics/nec-requirements-ground-fault-circuit-interrupters-gfci

https://www.osha.gov/pls/oshaweb/owadisp.show_document?p_table=STANDARDS&p_id=9881

If you don't know the answer to this question, you should not be in a position to make the decision!

Certainly, asking an anonymous forum to give you advice on life critical circuit protection is reckless and irresponsible.

YES GFCI IS REQUIRED.

okay... we've been asked by our safety manager to install GFCI on the panel board... to me it didn't make any sense as the welding plants are installed on a separate stand... all the welder has to work on are -ve and +ve terminals coming out of the machine... why would the gfci be required in this case.. i want to understand...

Just do as your manager has told you to do, you clearly aren't the one to make such decisions.

The GFCI isn't to protect the LV + - O/P it protects the incoming to the set, in doing so protecting the operator against any leakage between the windings or to the casing.

Having read this and other threads you have started I think you should find a new occupation or stick to welding.

Interestingly NFPA 70 (aka NEC) Article 630 "Electrical Welders" is silent on the matter, with Section 630.1 Scope referring only to "...(welding) apparatus...that is connected to an electrical supply system..." Typically this is interpreted as "look back to the supply side and its requirements" (my words, fwiw), so you'll have go back to the appropriate sections that deal with everything from your generator installation up/down to, and including, the welding receptacle(s).

Hire a qualified electrical contractor/engineer and let him deal with the AHJ (Authority Having Jurisdiction), then abide by their decisions (in writing); otherwise you'll be liable for any lawsuits that result from any electrical incident/accident from the entire installation.

ACTUALLY, taking a strictly literal interpretation, a GFCI is a very SPECIFIC device that is ONLY required on 15 & 20A single phase residential circuits into which devices can be plugged into receptacles in wet areas, or outdoor receptacles. It is SPECIFICALLY limited to a maximum of 6mA of ground current, designed to trip at around 4mA. You basically cannot plug a 380V welder into one, so the entire question is moot.

I would also further speculate that anything rated for 380V is not designed to be used anywhere in the USA, so referencing the U.S. NEC also becomes moot.

Now IF, once again having to INTERPRET what you MIGHT be attempting, is that you are in the U.S. and for some strange reason are compelled to try to connect s 380V welder here, so you have bought a custom transformer to feed it, AND you have investigated and discovered that it will indeed work on 60Hz because if designed for 380V it is likely designed for 50Hz, then MAYBE you are asking if you must provide Ground Fault Potection, aka GFP then the answer would be, no. You are not compelled to provide GFP unless the service feed to it requires 1000A or more. You can, at your discretion, add it if you like.

In N.S.W Australia - where I reside - it became law in 2011 for all socket outlets rated at 20 amps or less in workplaces to be RCD protected. This replaced the previous residential only requirement. This covers many smaller 3 phase welders, but wouldn't apply to the OPs ones.

All existing workplaces had 12 months to begin implementation, and 4 years to fully comply with the rule.

My understanding is that NEC rules were expanded in 2002 to include a number of non residential activities - ie. 547.5G agricultural buildings, 511.12 commercial garages, 555.19 marinas and boatyards, etc.

I had 30mA RCDs (minimum trip 15mA) installed for all outlets, both single and three phase, at my last workplace back in the nineties, 3 phase welders were regularly used from these outlets with no ill effects.

3 phase RCDs are available here up to 100 amps off the shelf and greater by order with trips ranging from 10mA to 300mA.

Thank you. That does clarify.

380/220V would indicate one of the Benelux countries so the NEC wouldn't apply. It's one of the few areas I don't have the codes/regulations for.

From y hands on experience GFI on anything but an outlet near a kitchen sink or bathroom is nothing but a nuisance and waste of good company time and money.

My experience is that a GFI on any portable generator/power station system is nothing but trouble. The primary problem being it's rare that any portable generator ever gets properly and sufficiently (If at all) earth grounded which makes the local generator frame ground nothing more than a floating ground and thus nearly useless.

Granted many will have their common line tied to their frame ground which then makes the unit safer for line to grounded objects but it also makes the GFI totally useless being it now has what is essentially a floating tap going someplace that is not of equal potential/ current path flow with the line side.

Now to make things worse welding power supplies often have some degree of internal connection between their lower voltage high current outputs and the frame grounds via capacitive coupling and or resistive coupling to bleed off any potential static charges that could be held or induced in the objects being welded on. That again makes for an odd combination of possible stray current flows that can mess with a GFI units ability to distinguish between a true earth fault and a false one.

So given that if you want to put GFI on a nonstandard multiphase portable generator powered welding system you might as well hire one guy to stand by the GFI and hit reset every few seconds after someone strikes a weld because you won't get a damn thing done other wise.

In the right applications and contexts of use a GFI is a very good thing. In the wrong ones where they serve no real gainful purpose they are just a waste of time and money and a source of a lot of frustrations and by my experience portable power systems and welding related work is not a place for them.

Thanks for your detailed response.

British Standard 7671.

BS7909

I can't say if one is required. I can say that if you install the GFCI, you should be ready for a lot of unplanned shutdowns if it uses arc detection as a fault condition.

To a WELDER? Riiiiight!

Cortland Richmond

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