by ericmark »
Thu Aug 10, 2017 8:05 pm
BS7671:1992 is I suppose when the regulations became widely know, it was at that point where people started to go to collage and take exams to show they had read them, it was the first reprint of the 16th Edition of the regulations and has since had many upgrades the two major ones being BS7671:2001 and BS7671:2008.
In those 25 years there have been many changes, in 1991 we had earths on lights, then we had the move to MCB’s rather than fuses meaning the earth loop impedance became much more important, the old ELCB-v has been outlawed and the RCD now is used for circuit protection on most circuits.
Volt drop allowance has been modified in those years, but the two major items which suffer when there is volt drop is the fluorescent lamp and refrigeration units. And you have both. Typically a freezer takes less than ½ an amp running, but a massive 10 amp to start, and it is the starting which causes the problem, they have an overload so should they try to start before the pressure has dropped then it will trip and reset it is hoped after the pressure has dropped, with a volt drop it can try restarting many times and can burn out the overload as a result.
2.5 mm² cable will carry 10 amp for around 70 meters before the volt drop limit is reached, so there should not be a problem, however raise it to 13 amp and it drops to 53 meters, 16 amp down to 42 meters, and at 20 amp down to 32 meters, it would seem your well within the limits, however this is from the consumer unit including any cable joining garage to house.
When ever is see the statement “I am competent” it rings alarm bells, the classification was dropped with amendment 3, but there were four classes of person, starting with ordinary, then instructed, then skilled, the highest was competent and I will admit the difference did not seem to make sense, skilled person can look after his own safety and competent can also look after the safety of others. A competent person is NOT the same as being a member of a competent persons scheme, maybe that is why the classification was dropped to avoid confusion.
There are as well as the regulations also laws, the laws vary area to area the health and safety at work act is nation wide, but Part P in England is different to Part P in Wales.
In the main outbuildings will drop into two types, the simple fuse connection unit (FCU) feeding the building with a second switched FCU with smaller fuse for lights, or the MCB/RCBO in main consumer unit feeding a sub consumer unit in the out building which in turn has an array of MCB/RCBO protected circuits. It would seem the former even though BS7671 would describe it as forming new circuits Part P building regulations don’t, although I have not seen any official document to say that. However once you use a consumer unit, then it will be seen as forming new circuits. So it seems very likely that the work is notifiable.
There are two or three methods depending where you live, either pay the local authority a fee, or pay a third party a fee (England only), or use a scheme member electrician. The latter is likely the cheapest.
The problem with all DIY work is 99 times out of 100 nothing alerts the authorities anything untoward has been done, so we get away with it. When it does go wrong however then the questions are asked. It seems daft in this country I can buy things which I can’t legally use, for example a ham radio can only be used by a licensed radio ham, but anyone can buy one, walk into the DIY sheds and they are full of things you are unlikely to be able to legally use, the regulations on wood burning stoves for example makes it very hard to actually fit and use one within what is allowed by law. However the DIY sheds still sell consumer units and the like to the general public.
There are surprisingly very few domestic deaths due to contact with electricity, although likely many more due to fire caused by the electrical items in a house, when it does happen then it seems the courts hand out really high sentences, often it seems not to the person one would expect to be held responsible.
Law has some odd rules it seems, but I have always said I don’t want to be in the firing line when case law is laid down even if found not guilty, these cases seem to take up to 10 years for the result to be declared.
I feel in my house I should be allowed to do anything which will not endanger others, however other people do visit my house in an official capacity, from post man to gas man even the double glazing salesman my house is his place of work, so the EAW act applies.
As to drops for each socket yes I have done that both to reduce the loop impedance and to remove as much wiring as I can out of harms way, but when you sign the installation certificate you need to be able to say why you have done it, you sign to say you have the skill to design, install and inspect and test. It is no good saying well I asked on a forum.
People seem to think they can do electrical work then get it tested, it does not work like that, every part has to be agreed, so when I took over my mothers wet room job, first thing was contact the council, when I state what I intend to do, they then say yes or no, and if yes they will say when they want to inspect, surface wiring likely at the end, but it is up to them not you.
They wanted to see my test equipment some £400 worth, and wanted to verify I had the skill, both my son and I are both electricians, however they would not accept his signature it had to be mine, as I had a degree he at that time did not.
I don’t like saying don’t DIY, however I think you need to understand what your letting yourself in for. I think the LABC Part P thing where is says you can DIY is really for non scheme member electricians to work on their own home. Not for normal DIY men.
