# Electrical islands and bonding



## gpop (May 14, 2018)

If the Mechanics build a metal stand like stairs that not connected to a building but can be close to electrical items should that structure be bonded to the building/ground?

Also if a island has a motor with a standard sized ground for the motor should a large bonding strap be installed as a know risk would be that a welder may incorrectly hook up his ground and use the motor ground as his ground path?


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## matt1124 (Aug 23, 2011)

Would you bond a metal ladder not connected to the building if someone we're to use an electrical appliance on it?

I don't follow the motor ground thing. Is the welder going to use the housing or shaft of the motor as part of the welding process? Or more specifically, what would you connect the two ends of the bonding strap to? The working lead clamp is not a ground clamp if that helps...


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## gpop (May 14, 2018)

the motor is on a concrete pad and it turns a drum. The drum doesn't touch either end so the only connection from the drum to any other frame work is via the motor ground wire. 3 times they have burnt up the wire to the motor by welding on the drum while there (working lead) ground in attached to frame work. So should there be a jumper between the island and the frame work around it.


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## matt1124 (Aug 23, 2011)

Oh I think I see. The motor is some sort of material positioner.

Sounds like they need to put the work lead on the work.


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## gpop (May 14, 2018)

matt1124 said:


> Oh I think I see. The motor is some sort of material positioner.
> 
> Sounds like they need to put the work lead on the work.



Yep you would think the big warning signs would be enough.


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## gnuuser (Jan 13, 2013)

gpop said:


> Yep you would think the big warning signs would be enough.


if that doesn't work taking the repair costs out of their paychecks will!

there is no excuse for not following clearly posted directions!


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## gpop (May 14, 2018)

gnuuser said:


> if that doesn't work taking the repair costs out of their paychecks will!
> 
> there is no excuse for not following clearly posted directions!


Last 2 times contractors paid the material and labor cost. I was wondering if a run of 4/0 welding cable bolted between the island and the frame (about 16") would be ok. At least that would protect the motor wiring


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## gnuuser (Jan 13, 2013)

it should be ok 
but any welder worth his salt knows that the return clamp needs to be attached to the work piece preferably near the weld.
too far away and the metal heats up too much and undercuts.
theres a fine line between a good weld and an undercut one.

one of my jobs was also a welding instructor (mig,tig,stick, and oxyacetylene, stitch and stud welding) and i am damn fussy about it! 

heck my teacher told me i could probably weld a fart if i could figure a way to clamp them together:vs_laugh:


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## trentonmakes (Mar 21, 2017)

gnuuser said:


> it should be ok
> but any welder worth his salt knows that *the return clamp needs to be attached to the work piece preferably near the weld.*
> : v








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## gpop (May 14, 2018)

I spent the first 6 years out of school making shop displays of which 2 years i spent behind a welding mask. If i never weld again it wouldnt upset me a bit.


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## paulengr (Oct 8, 2017)

First concrete is a decent conductor. It tends to absorb and hold onto moisture.

Second even if you improved the motor frame grounding welding on the shaft or an attachment will just arc through and destroy the bearings. Either welder retraining in the same craft or if that doesn’t work retraining in a new craft is the only solution.

Generally steel bolting and concrete works pretty well as structural grounding if the electrical equipment is metal enclosed and bonded. Google Faraday shields for why it works.



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