My Arduino Mega controller is mounted on a metal backplate which is mounted inside stainless box which is mounted to a metal frame and box is earth grounded. The guy needs to Weld to the metal frame. Do I need to remove the controller before he Weld to the frame to prevent damage?
Hi,
Main question is are there wires that come out of the metal box?? If it's TOTALLY contained, and the AC power to it can be really disconnected from it and grounded, you should be OK.. IF there are wires coming out to sensors or actuators or operator interface you need to remove any sensitive electronics.
Other: The welder has a choice where the welding 'ground' is connected. That should be a really good connection close to the point the welds are done, so the welding current stays in the physical area.
Thanks. Yes, the wires go out to NO/NC switch limiters that are mounted to the metal frame as well with pin inputs connected to NC side of the switch block and 110v to NO side. I'll make a trip to remove the controller. I already warned him of the potential damage anyway.
What is being called the 'ground', is really the positive electrode. the one with the rod is the negative side of the welder (machine). Hence the more prevalent hazard of 'ground loops' and stray voltages.
It is ALWAYS a good idea to remove all connections to electronic assemblies (including ground paths through mounting hardware) before arc welding attached structures.
Keeping the return electrode as close to the welds as possible is a good practice, but not a guarantee of safety to attached electronics.
I think it wise to remove the electronics first.
There have been stories here of welders causing problems.
One was on a nuclear sub where you would expect everything to be bomb proof but arc welders sent the instrumentation crazy.
There are actually two areas of concern - the first is because of the current welding (either AC or DC), you can get significant voltages across the metal frame from the IR drop. The other aspect (besides the splattered hot metal) is that because of the high currents involved, you can induce significant voltages in any wires near the wires from the welder (either side) as that field fluctuates. That can be quite a "pulse" when you have a 100 amp transient on a wire next to sensor wires etc. People often overlook the induced currents from the fluctuating currents in the welding wires - it is NOT a steady 100 amps or whatever current you are running. Been there, done that 
Have both a MIG welder and a traditional AC stick welder. I'm always careful where the cables are relative to other wiring.
Thank all of you very much for your info.
Having seen the securing studs holding the steel panels onto a 66kV breaker switchboard sparking merrily whilst the breaker was being 'exercised' I would always recommend removal of electronics when any form of electrical welding was taking place. Enclosure within a steel enclosure is no guarantee of "no-damage". Steel is an amazingly poor conductor of electricity (relatively speaking) and the 'stainless' version is usually worse than the 'mild'. The resistivity of stainless steel is around 50 times higher than that of copper.
To reduce the risk of damage to your circuit through electrical energy, you could always weld using oxy acetylene
Agree with other posters on the advisability of removing any electronics from an electric welding environment.
And even oxy-acetylene gets things very hot - electronics don't like that much either....
regards
Allan
6v6gt:
To reduce the risk of damage to your circuit through electrical energy, you could always weld using oxy acetylene
No, no - use the arc welder to put things together. Use the oxy acetylene cutting torch to take it apart when you discover you welded it in the wrong position (that is why I have a cutting head for my torch )
Oxy-acetylene is a very messy way of taking things apart - for thinnish stuff I use a 1mm thick cutting disc in an angle grinder, and for a bit thicker (up to half inch or so) a plasma cutter ...
Of course, if you're breaking up old ships it's just the job!
regards
Allan
Have not quite figured out a good justification to the budget director (AKA wife) for a plasma cutter yet. But I'm working on it
Plasmas are effective and quick - and leave a better approximation to a weldable edge.
You can get attachments for a TIG reasonably cheaply if you already have one.
I should work on it!
regards
Allan
allanhurst:
You can get attachments for a TIG reasonably cheaply if you already have one.regards
Allan
Can the output pin of a nano handle that ?
Boardburner2:
Can the output pin of a nano handle that ?
Well, if you can weld with a pencil, what's the harm in using the output of a nano
possibly not
R
A
turbofreak:
My Arduino Mega controller is mounted on a metal backplate which is mounted inside stainless box which is mounted to a metal frame and box is earth grounded. The guy needs to Weld to the metal frame. Do I need to remove the controller before he Weld to the frame to prevent damage?
If you are in any doubt (which you must be to ask), remove it.