If your supplier agrees that their tails to the meter are old, perished and unsafe, they will fit new ones. There will be a large cable (somewhere) either coming into your home underground or off a pole, or sometimes (in older flats and terraced houses) it may continue to you from an adjacent property.
There wil be a supplier's fuse before the meter. If you tell them you are thinking of having a 45A shower installed you can ask them to check that their fuse and their cable is adequate. If they renew it, you can ask them to provide a new earthing point, which they will probably do free, or might charge £60 or so. It is your responsibility (or an electrician employed by you) to connect this point to your consumer units and metallic services (water, gas, oil, air con). this is very easy.
A DP isolator is a big switch that cuts all power on both Phase ("Live") and Neutral, so isolating your installation from the mains. the suppier may installl one for you after the meter, or there may be a charge, or you may have to provide one and new tails (=big wires) to go into the meter.
An RCD is a thing that cuts the power when it detects that current is leaking to earth, e.g. if there is water in an electrical appliance, or you have run over the cable with a lawn mower.
An MCB is a thing that replaces one of your fuses, and trips when there is an overload or fault current (I happen to have a numnber of old Wylex ones
hence my remark)
An RCBO is a single device that includes an MCB and an RCD for a single circuit (so if there is a fault it does not cut the power to other circuits in the house). They work out more exensive than using just one RCD for several circuits. Some people consider them very superior.
there is a lot of stuff in the top few items in
http://www.diynot.com/forums/viewforum.php?f=8
There wil be a supplier's fuse before the meter. If you tell them you are thinking of having a 45A shower installed you can ask them to check that their fuse and their cable is adequate. If they renew it, you can ask them to provide a new earthing point, which they will probably do free, or might charge £60 or so. It is your responsibility (or an electrician employed by you) to connect this point to your consumer units and metallic services (water, gas, oil, air con). this is very easy.
A DP isolator is a big switch that cuts all power on both Phase ("Live") and Neutral, so isolating your installation from the mains. the suppier may installl one for you after the meter, or there may be a charge, or you may have to provide one and new tails (=big wires) to go into the meter.
An RCD is a thing that cuts the power when it detects that current is leaking to earth, e.g. if there is water in an electrical appliance, or you have run over the cable with a lawn mower.
An MCB is a thing that replaces one of your fuses, and trips when there is an overload or fault current (I happen to have a numnber of old Wylex ones
hence my remark)An RCBO is a single device that includes an MCB and an RCD for a single circuit (so if there is a fault it does not cut the power to other circuits in the house). They work out more exensive than using just one RCD for several circuits. Some people consider them very superior.
there is a lot of stuff in the top few items in
http://www.diynot.com/forums/viewforum.php?f=8
