What are the rules on replacing/removing/installing an electric oven?

[ajohn]

Well…it CAN be plugged in to a ring final, but SHOULD it be?
The guidance in BS7671 is that loads of more than 2KW should be on their own circuit, rather than plugged into an RFC.

What the site guide say specifically on cookers is
"It is recommended that electric oven are supplied by a separate circuit however for lightly loaded circuits ovens of a rating of 13A or less may be connected to a ring final circuit"

The 13amp fuse aspect and switches comes from switching requirements for permanently connected items. Again from a ring final. That on the face of it doesn't apply to 4mm radials.

My feeling are better summed up by carry on adding spurs In other word best to do it properly with the switches even though those are only recommended.

I haven't got the full regs out as several sections would have to be tied together - that is what the site guide is for, avoiding that aspect. If you know of a reg that states differently give me the number.

 

[EFLImpudence]

Ajohn:

You have previously stated a caveat that you are not an electrician; presumably meaning that you are not 100% certain that what you write is correct.

Whilst what you have written may not actually be wrong, it is not the definitive solution to any problem.

Also, beware of quoting the "On Site Guide" (which is what I suppose you mean) which, among its mistakes, usually gives the worst case scenario for any topic; meaning if you follow it everything will be alright but that does not mean that is what must be done.

The nominal voltage of 230V might be a spoof but it is the voltage used for all the calculations and values given in BS7671. If you want to use 240V you may but you will have to adjust all the values to see if they comply.

 

[EFLImpudence]

I haven't got the full regs out as several sections would have to be tied together - that is what the site guide is for, avoiding that aspect.

Yes. Doing things without knowledge and having to think.

If you know of a reg that states differently give me the number.

There are lots.

Appendix 15 is not a regulation.

 

[ajohn]

Yes. Doing things without knowledge and having to think.


There are lots.

Appendix 15 is not a regulation.

appendix 15 in this respect is a can generally achieved so all comes back to what I mentioned initially - what else is on the final circuit and what is it's current rating. The socket being used as it may not be on a 32amp circuit, other things already connected and the rating of the appliance that some one wants connecting. Then thoughts /sums about diversity. A bit of an imponderability on ovens as it depends on the temperature they are at and how well they are insulated. Worktop types are often rather bad in that respect. Free standing little or no better.

The site guide contains nothing that does not need thought even the table of cables and length that can be used without calculation because they assume some aspects that will be checked and can be different if a cable is installed as it should be.

15 is also a clarification of some aspects of section 4. That's the one that can over ride parts elsewhere. It also clearly shows that 2 double sockets can be run on one spur providing it's fed by a fuse unit. Far more clearly than the guide. Using 1.5mm for this amuses me but suppose it saves a few pence and it still likely to need some 2.5mm for spuring an FU.

230 - 240v. Anyone that thinks it really is 230v has very probably got a duff meter or has never measured it. Using 230 for calculations is an entirely different subject,

Maybe I am more of one than you think.

 

[JohnW2]

... Using 1.5mm for this amuses me but suppose it saves a few pence and it still likely to need some 2.5mm for spuring an FU.

In fact, despite what the diagram in Appendix 15 shows, one could actually also use 1.5 mm² cable for the connection from ring to the FCU if one wanted to, since a real regulation in BS 7671 allows it to be protected by the downstream fuse in the FCU.

Kind Regards, John

 

[ajohn]

I was wondering about mixing 1.5mm and 2.5mm in the same hole - I'm a bit like that. It sounds awkward so would use 2.5mm and wouldn't be concerned about using 2.5 throughout it.

Some electricians will fit a spur when the CU hasn't got an RCD. They use a FU with a built in RCD. I say some as opinions may vary. When done that way I have wondered if it's possible to fit a small metal din style box near the CU and protect the entire circuit the spur is on with an RCD. I've not seen signs of any exclusions of doing it this way. Not that I have looked that hard.

 

[EFLImpudence]

I was wondering about mixing 1.5mm and 2.5mm in the same hole - I'm a bit like that.

Terminate them so that it is satisfactory.

It sounds awkward so would use 2.5mm and wouldn't be concerned about using 2.5 throughout it.

Ok.

Some electricians will fit a spur when the CU hasn't got an RCD. They use a FU with a built in RCD.

FCU.

I say some as opinions may vary. When done that way I have wondered if it's possible to fit a small metal din style box near the CU and protect the entire circuit the spur is on with an RCD. I've not seen signs of any exclusions of doing it this way. Not that I have looked that hard.

Commonly known as a Shower CU or Garage CU.
https://www.toolstation.com/search?q=shower unit

 

[JohnW2]

Some electricians will fit a spur when the CU hasn't got an RCD. They use a FU with a built in RCD.

In terms of currents regs, they can't really get away with that any more if the cable is 'buried' (in a wall) anywhere between the CU and the FCU, since that cable, in itself, is then required (by current regs) to have (upstream) RCD protection.

Kind Regards, John

 

[ajohn]

The regs shouldn't be applied retrospectively - or so it seems. That I suspect is why some may install a spur this way. Plastic consumer units are an example. Initially many electricians went around saying must replace when they needed to do anything. That was clarified - check tightness of the connections. Wired fuse CU's are still legal. Fuses can still be used for short circuit protection. RCD's are the new parts also used to get round earth circuit resistance problems. There have been comments that suggest it's up to the electrician in respect to surge protection in a guidance respect. Not really looked in detail. I did look at the performance and thought still fit a plug type on some equipment.

I've never spent several intellectual hours on the regs to see what must be updated if say a cu is upgraded or a new circuit added. That's assuming anything is clearly stated. If notifiable a number of things will be checked, indications are every circuit and a report is generated. It's notified. If the regs shouldn't be applied retrospectively all may be ok in this respect as they meet earlier ones. A pass for me at the moment as I feel the actual regs don't have a format that is really suitable for people to work to except when it gives specific examples in some areas. Hence guides clarifying things in places.

Going back to the topic in some respects DIY's can do all work needed. It's specifically stated in the guide to building regs. They must inform building control first and building control then becomes responsible for checking and approving it. For an electrician that does work regularly it's far cheaper to join one of the approved competent person schemes. They usually get other benefits as well. A diy'r might also find an electrician who will allow them to do the donkey work. How much is likely to vary but I doubt if many really like channelling walls etc. Some companies employ monkeys to do work and have an organ grinder with them that can check and pass things off. There were mutterings about electricians passing off work done entirely by a diy'r. Seem to have gone / not sure.

 

[JohnW2]

The regs shouldn't be applied retrospectively - or so it seems.

There is no requirement for new regs to be applied retrospectively to existing installations.

However, there is scope for debate (and differing opinions) when 'new work' is involved. For example, as I was implying, if one extends an existing circuit, by adding an FCU and things fed therefrom, some would say that there would then, strictly speaking, be a requirement for the whole circuit (back to the CU) to comply with current regulations (hence RCD protection required for any buried cable).

As I say, opinions about this will vary.

Kind Regards, John

 

[ajohn]

Opinions varying is the worrying bit really as the responsibility in respect to building regs is the property owner not the person that does it. I think there has been talk of changing that. Just talk. There was a gas explosion a few miles from me. A fitter did what he was told to do knowing it was wrong and finished up in prison. According to the news supervisor - no problem.

My main interest stems from feeling we aught to upgrade the CU. Companies are spending millions on new stuff to stick in them so it's not exactly static but more worrying no way of knowing what work will need doing in total. So decided to fully test the lot myself first. I'm not at all keen on having the house ripped apart. That might influence the decision. Repairs are a little different to upgrades / changes as well.

 

[JohnW2]

Opinions varying is the worrying bit really as the responsibility in respect to building regs is the property owner not the person that does it.

The Building Regs are the only la with which one has to comply and, as far as electrical work is concerned, that consists of just one sentence ("Part P") which essentially just says that electrical work must be done safely.

"The Regulations" which we discuss, debate and attempt to interpret here are BS 7671 (aka The IET Wiring Regulations) which are non-mandatory and have no force in law.

Kind Regards, John

 

[flameport]

I've never spent several intellectual hours on the regs to see what must be updated if say a cu is upgraded or a new circuit added.

BS7671 applies to any alterations or additions to an existing installation, as well as new installations.
Therefore if changing any part of an existing circuit or extending a circuit, that circuit will need to comply with whatever version is applicable at the time of the alterations. That may well involve adding RCD protection to it. Other fundamental requirements such as earthing and bonding must also be met.

If a consumer unit is changed, all of the circuits connected to it need to comply with the current version of BS7671. That is why the physical replacement of the unit is a minor part of the work - the bulk of it is the testing, inspection and inevitable repairs to the existing circuits.

If someone has an old installation and doesn't want it upgraded they can keep using it for as long as they want - provided no alterations or additions are made.
Replacing items is not an alteration or addition.

 

[ajohn]

"The Regulations" which we discuss, debate and attempt to interpret here are BS 7671 (aka The IET Wiring Regulations) which are non-mandatory and have no force in law.

I think there is a misunderstanding there. It is part of building regulations. In a sense these have no force in law but what matters is the outcome. Say some one builds something that departs from in some way they can be made to take them down. BS7671 in many respects is privatised building regs enforcement some aspects of which can also be handled by local building control. The equivalent taken down here is disconnection and don't use stickers. There are others about that have no force in law. The party wall act for instance.

 

[Taylortwocities]

The only law (statutory instrument) is Building Regulations Part P.
This is it


Along side this is the Approved Document for Part P. This is a guide to advise how the law can be complied with.
In the approved document is says that a way to comply is to follow BS7671. You could install your electrics to a completely different standard, but you would have to be prepared to convice an overseeing body (LABC, for instance) that your approach is acceptable.
LABC don’t have the wish to mess around , so they use the Approved Document, with its notification requirements, as the Bible by which electrical installations shall be carried out.