We just had a bloke round from Scottish Gas to fit a new meter. I was out at the time but he told my wife that there was a current flowing through the earth connection from our fuse box to the gas pipe. He didn't seem to mind working on the system and said not to bother when my wife offered to turn off the electrics before he started working. However she's now worried about whether or not there's a problem with the electicity supply.
Is this something I need to be worried about? We've never had any problem with shocks or the like from any of the pipes in the house.
It MIGHT be simply a small potential, caused by one of a number of reasons, existing between the consumer unit earth terminal and the pipework but it could be something much more serious such as failing insulation on an appliance in the house. If you are not au fait with, or equipped for, carrying out a proper electrical system test I suggest you get a professional in to investigate. Don't cross your fingers and hope.
I dont know if he was right or not, one can draw that conclusion wrongly. If he is, it may be nothing of any significance, or it may be live to earth leakage that may increase at any time, adds to your bill, and may cause something to burn.
If it were mine I'd put a clamp ammeter on it and see what the current is. If it turns out to be a big fat raisin it might need sorting out. Then, with no-one else in the house, I'd disconnect the bond and see what pd is across it. Then a picture should emerge as to whats going on. Dont do the disconnect/measure if youre not sufficiently skilled though, as it could make normally safe objects live.
Current procedure is that most people involved in meterwork are issued with a device commonly known as a voltstick which is specified to indicate a contact voltage of 50v or more. The reason why these are issued is that there have been a number of recent deaths and serious inuries involving gas workers involved in meter work. We can speculate as to why this is so. My thoughts are that it is becuase of the upsurge in diy electricians and poorly trained/unqualified people doing electrical work which leads to current flow on piping/earthing systems.
As Gasmen are not electricians they are advised to test pipework where they are working with the voltstick. If it glows there is a procedure in place for informing the customer.
An inspection would then be advised to confirm/isolate the fault. The use of continuity bonding leads should ensure that there is no risk of injury to the engineer when he changes the meter.
As i say,in years gone by,bonding leads were thought of as almost superfluous/not needed but these days they are a definate MUST becuase the number of incidents has risen sharply.
During meter changes, sure, and temporary connections can be clamped on by the person doing the work. For daily domestic use they are of little significance.
Increasingly the water main is plastic so if the main earthing terminal or (earth rod on a TT supply) is disconnected the gas main becomes the only effective earth path. If there are a couple of leaky non RCD protected appliances let alone one wired up wrong, the removal of the gas meter becomes a serious hazard.
The polyethylene gas pipe (new plastic one) is commonly 20mm diameter for most domestic properties and will therefore easily feed up a typical old 1" bsp steel service pipe. The threaded end of the old steel pipe is then fitted with a new service head adaptor which connects to the new plastic pipe. The annualr space between the old steel service and the new plastic service is filled with a special filler which is pumped in in liquid form and then sets due to chemical reaction between the constituents. In difficult situations, i.e old steel services which have bends,there is another material known as flexserve which is a kind of corrugated PE pipe which can be fed round bends more readily with the aid of special tooling. The internal termination is similar.
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