as they must be bonded anyway can anyone tell me what difference it makes to have the copper pipe run outside?
Sorry, Iāve been working away last week and see thereās been a lot of discussion in response to my question. Thanks for all the positive points of view and healthy debate.
I feel I should reply to the discussion points about my statement of risk with exposed metal work outside a building. As Iāve said this is only one of the reasons why Iād prefer to have an outside mdpe gas pipe from the meter to the boiler.
The electrical dangers here shouldnāt be confused with the bonding requirements for services within a dwelling as these are very specific and are needed to reduce danger within the home as discussed below.
The wiring regulations use terms like āPersons shall be protected against dangers that may arise from contact with exposed conductive parts during a faultā they also have requirements to limit fault current magnitude and duration to such a level as will not to cause danger. With this in mind, consider the following: -
Danger can arise when any metal work, be it a copper water pipe (with tap), copper gas pipe or even an outside metallic security light is fitted to a building where the electrical service to a home uses the combined neutral/earth arrangement offered by the electricity supply company. Why? If a neutral fault occurs the earth conductors of the whole installation can become live at a voltage above true earth. As most users of this forum know, the wiring regulations call for equipotential bonding within a building (gas services included) to reduce the risk of injury in these circumstances, but this measure is only effective within the building. If this metal work is taken outside (e.g. gas service in copper around the house or a copper water pipe and tap) a person can make contact with the metal work and if this is during a neutral fault, can receive an electric shock. Of course, this may also occur inside the house but the risk of receiving a leathal shock is reduced through equipotenial bonding and generally having a dry and carpeted environment. Outside is a different matter altogether and in the extreme, a child grabbing hold of an external water tap in bare feet standing in a puddle of water (during a neutral fault) could have lethal consequences.
Before a reply comes back with āthe RCD will protectā argument, it wonāt. If the neutral fault is on the mains side of the cut out the earth will become live and this conductor will pass current through the person āholding the outside metal workā to true earth, completely bypassing the RCD.
As a disclaimer, if anyone wants advice about specific installations you need to consult a qualified electrical contractor as this discussion is of a general nature. Hopefully it will enhance debate and questions leading to a safer environment.
I'd also like the comfort of knowing the mdpe pipe I'm laying for my gas safe plumber to connect is within regulations and is one of the better options I have open to me.
Thanks for the responses and keep the debates going.