Earth a welding trolley?

[skotl]

I'm in the final stages of building my trolley and tomorrow's plan is to mount a 32A socket on it for the welder, as well as a 4 gang that I can plug the plasma and grinders into.

There will be a cable coming into a 32A isolator switch, through to a junction box that will feed the 32A and 13A sockets.

It occurred to me that I should run an earth from the junction box to the trolley's chassis as it's sitting on rubber wheels so is mostly isolated. I say mostly because earth leads from the welder and plasma will contact other grounded items, plus it will inevitably come into contact with other grounded items.

But then a bit of me wonders whether it is more dangerous to have the trolley presented as a route-to-ground if any of the kit develops a fault.

Thoughts?

Edit: The garage is RCD protected, if that makes a difference

 

[sparkysy]

Hi Skotl
Just a quick thought will the sockets be a 4 way extension joined into the other supply as it will only have 1.25mm or at most 1.5mm that will not be rated at 32a as the 13a fuse in the plug top protects it. I would use the same size cable and put metal clad sockets on there which If you earthed the boxes would also earth the frame. forgot to say earth and the welders (earth) are not the Same thing really so would not be a reliable earth.
Sy

 

[skotl]

Hi Skotl
Just a quick though will the sockets be a 4 way extension joined into the other supply as it will only have 1.25mm or at most 1.5mm that will not b rated at 32a as the 13a fuse in the plug top protects it. I would use the same size cable and put metal clad sockets on there which I you earthed the boxes would also earth the frame. Sy

Cheers Sy

I did consider that as I chopped the 13A plug off the 4-way but I figured that each of the grinders has either a 5A or 13A fused BS1363 plug on it, so that should cover the load.
Do you think it's worth putting a 13A FCU between the incoming feed and the 4-way?

I'm reading that as a +1 for earthing the trolley?

 

[rikrobson]

I've also a 32A feed to my trolly then a breaker box for a 32a mig supply a 16A for the plasma and a 16A for some sockets. Thesis all earthed to the metal frame. The feed is off an red. Therefore if there is an earth fault or something live touches the frame it will trip. The r-tech mig has a chassis ground to that's connected to the trolly frame Aswell.

 

[rtbcomp]

The "earth" (return) on the plasma & welder aren't connected to the cases, and should be kept separate from the mains earth. The cases themselves should be earthed to the mains via their mains cables.

I would earth the frame, if a live came loose, got chaffed or a socket got smashed you would need a safe path to earth to blow fuses or trip the RCD.

 

[sparkysy]

Sorry Skotl it was getting late last night, it's up to you as has been said you could put a circuit breaker in or just use the same size cable for all wiring. Definitely earth the metalwork to make it safe!
God isn't it amazing how everyone agreed with the comments made, that hasn't happened for a while!!

 

[skotl]

The "earth" (return) on the plasma & welder aren't connected to the cases, and should be kept separate from the mains earth. The cases themselves should be earthed to the mains via their mains cables.

I would earth the frame, if a live came loose, got chaffed or a socket got smashed you would need a safe path to earth to blow fuses or trip the RCD.

Sorry Skotl it was getting late last night, it's up to you as has been said you could put a circuit breaker in or just use the same size cable for all wiring. Definitely earth the metalwork to make it safe!

Good stuff - thanks guys - I'll earth it.

God isn't it amazing how everyone agreed with the comments made, that hasn't happened for a while!!

There was a similar debate on diynot/electrics UK, which ran on for pages and pages, and people definitely did not agree over there!
But there's a far friendlier and mature level of discussion on here rather than diynot, of course

 

[sparkysy]

Depends on how you mount the boxes 6mm bolt would provide a suitable earth with a crimp lug on the bolt. And that is assuming the sockets are fixed to the frame. But you could put a flying earth to the frame too, if it was in the socket box there is no chance of it getting cut or damaged either.

 

[sparkysy]

Ah no sorry pdg I should of made myself clearer, those lugs in the back of the boxes have got more and more rubbish, with things getting more cheaply made to the point where you wonder weather it would even earth the backbox properly!

 

[sparkysy]

Love it! Yes you could make it all class 2 with plastic accessories and that would also be perfectly acceptable

 

[skotl]

That may be a tad too advanced for my abilities

 

[sparkysy]

Nah its easy Skotl and would be no problem for a man of your skills! Class 2 is just making sure that the metalwork is insulated from the end user so that the electric connections cannot cause a fault to the frame itself. Using plastic accessories and fixing it to something other than the metal frame eg insulated plastic panel would also comply and be safe, especially as you say you have rcd protection as well anyway!
Sy

 

[skotl]

Nah its easy Skotl and would be no problem for a man of your skills! Class 2 is just making sure that the metalwork is insulated from the end user so that the electric connections cannot cause a fault to the frame itself. Using plastic accessories and fixing it to something other than the metal frame eg insulated plastic panel would also comply and be safe, especially as you say you have rcd protection as well anyway!
Sy

Huh... funnily enough I plan to mount the various bits of electrical plastickery onto a lump of wood and then bolt the wood to the trolley. So, in that case, do you think I wouldn't run an earth strap to the trolley?

 

[sparkysy]

Oh B@lls what has @pdg started yes that would work but be Careful with the fixings for the boxes as they are metal, and coming from inside the electrical enclosure. Fixings on class 2 installation are usually seperated from the enclosure by insulation and caps in the face to hide cover screws.

 

[sparkysy]

Should of made that clearer, the socket boxes would have to be plastic. But the screws into the wood would compromise the class 2 rating unless insulated! Hope that makes more sense.
Sy

 

[sparkysy]

^^^ what @pdg says above! It's getting far too complicated!

 

[skotl]

Don't worry - I'm going to do all of the above to keep everyone happy

The plastic bits will be bolted to a piece of wood, which will be bolted to the trolley without any insulation of the bolts. Then I'll add an earth strap!

 

[skotl]

All done! Will get some pictures up later in the week.

Thanks for everyone's help

 

[skotl]

Finished article...