Safety earth for the safe earthing of plumbing and consumer unitIts an important safety item for your checklist. The correct earthing of all the plumbing and the consumer unit.
The reason is very simple. Any faults in the system like a cut wire or meltdown of an appliance will have live power looking for the quickest way to earth. If that’s you, it will be very unpleasant. The result is often fatal. So, we make sure all these parts to your house have a nice thick earth cable to ensure an easy path to ground, away from you. As all boilers are connected to live mains whether they are gas, oil(to run the ignition and timer systems), or electric heated. This means that if there is a fault in the boiler it could make all the radiators live. The way boiler are constructed this is highly unlikely, however, just in case. The building regs state that radiators must be grounded.
Some electricians assume that means you must have an ugly green and yellow wire attached to the radiator with a big metal tag for all the world to see. In truth that’s not the case. It needs to be earthed if its connected with copper pipe to the boiler. Not if its connected with plastic grey pipe(or whatever colour you bought). And the earthing only has to have a continuous, unbroken connection. So, you can place the earth strap on the other side of the wall or floor boards as long as you can access it for inspection. The copper pipe itself provides a continuous connection so there is no need to earth each individual radiator. The simplest way to earth the lot of them is to do it at the boiler.
Next on the list is to earth the gas mains(after the meter as before the meter belongs to the gas supplier) and earth water mains within 600mm of entering the house The final termination should be at the supplied earth on the incoming power cables. Your electrician will show you where its safe to touch.
There is solid argument for using plastic pipe as it removes the large earthing surface in each room I.E the radiator, making it safer. It sounds backwards from what we have just been discussing but look at it this way. Humans with dry hands make lousy conductors of electricity. Wooden floor boards and even carpet are not favoured routes for power either. so if you get a jolt it may not be lethal as the power cant travel well through those mediums. However if you have a whopping great earth plate(radiator or metal bath tub) to transfer the power from you to earth you will be much more likely to get a fatal shock. That makes a powerful argument for the use of plastic pipe in bathrooms, and the rest of the house for that matter. The plastic pipe may be filled with water but tests have shown it is a poor conductor.
By the way. As plumbing fittings for baths often have pft tape(thread tape) which can isolate the bath it is considered a poor conductivity fitting so the bath or sink must be earthed individually.