Electrical box, where your fuses are located. That box is usually made of metal and is grounded properly. Where I live old style grounding is done with just a loop of wire inside the outlet, since wires are live and ground, some places have live and live. Modern style of grounding is done with proper yellow green wire all the way to electrical box. Kitchen stainless steel sinks or counter tops should be grounded. Hot water heater. Bathrooms should have protective earth outlets.
What about just making sure everything is in same potential? And charges have to dissipate and equalize. Doesn't have to be just the exact protective earth, but then you need to make sure there is no danger of electric shock, which might be easier said than done.