Hi,who has asked you to "alter" this scaffolding?
The outfit responsible for erecting it,and whoever commissioned it,would or should have done a risk assessment,and any requirement to earth/bond or otherwise modify the structure,would be in that.
You cannot start clamping cables to a structure which at end of build up,and on a daily basis,should be inspected visually,to conform to exactly what was commissioned and agreed.
There could be a discussion regarding any unauthorised work,such as this,as introducing a potential electrical risk,where there was not one previously.
This is a common issue,with large,long-running refurbs,on churches,community halls,scout halls,etc,where "bob" on the committee,who did a bit of electrical work when working,mentions during a meeting,that there needs some "earthing",and he can sort it...
If i am wrong,i apologise,which means there is a request through specification,in which case,simply follow that directive.
