Question about electrical regs

[woodspiral]

Hi,

Any electricians on this board?

Does anyone know where I can get a 100% definitive answer to an electrical regs question? Two electricians and two appliance installers have verbally told me that a particular setup is against the regulations and non-compliant, but according to NICEIC, they are saying there is only an advisory against the situation under the BS7671 regs, not a mandatory prohibition against it.

The situation is that a hob and cooker are sharing the same isolation switch and terminal block.

Thank you,
Woodspiral.

 

[mikej460]

When I installed our kitchen I faced the same question and everything I read stated they needed to be separate and, if you have a split consumer unit, one on each side. I wouldn't challenge what's legal or not, go with the safest setup and follow the advice of the experts.

 

[woodspiral]

When I installed our kitchen I faced the same question and everything I read stated they needed to be separate and, if you have a split consumer unit, one on each side. I wouldn't challenge what's legal or not, go with the safest setup and follow the advice of the experts.

Thank you, Mike. The issue I face is that I need to know definitively what the regs say, for legal reasons. It's a very long complicated story I don't need to bore everyone here with, but the bottom line is that I need to know from a regs point of view if it is technically legit or not. Clearly having them split is going to be safer, but if they are shared it may not strictly be against the rules?

 

[flying haggis]

you dont have to have a switch. what is the rating of the hob and oven? dont forget that an "old fashioned" cooker had hob and oven on same circuit !

 

[woodspiral]

you dont have to have a switch

Thank you flying haggis, but can they share the same terminal block?

 

[HamsterJam]

Have you asked those that are telling you the installation contravenes the regs to advise precisely which clause(s) that the installation is contravening?
Also bear in mind even if it isn’t a direct contravention to the letter of the regs, going against an approved code of practice might also be a difficult position to defend.
Ultimately if this a legal issue, you may need professional legal advice.

 

[woodspiral]

Have you asked those that are telling you the installation contravenes the regs to advise precisely which clause(s) that the installation is contravening?
Also bear in mind even if it isn’t a direct contravention to the letter of the regs, going against an approved code of practice might also be a difficult position to defend.
Ultimately if this a legal issue, you may need professional legal advice.

That would be a good thing to do, thanks for the idea, HamsterJam. It would be good to have a copy of the regs to refer to, but I can't find them online. They seem to be absurdly expensive to buy.
The legal route is exactly the course I'm considering, but I before entering a fight, I need to know my chances of winning.

 

[Spectric]

the BS7671 regs

These regs are not statutory and are only guidance regarding best practice for electrical installation and there is always some interpretation within reason. What you have to remember is that they are a double edged sword because if you ignore or do something else rather than follow best practice then they can be used by the HSE to prosecute you if there is an incident or someone gets injured.

The situation is that a hob and cooker are sharing the same isolation switch and terminal block.

In other words they are both fed from a common protective device, and is this terminal block part of an old cooker connection point for a single unit, ie an electric cooker with both hobs, oven and grill. Here you could have a 6mm or larger cable on a 40 amp fuse and your appliances connected to the terminal block may well have cable sizes that could not handle potential fault currents.

You have two appliances and without knowing the power ratings then I have no idea on what they may be pulling in terms of current but I would always supply each appliance from it's own protective device with isolator(switch) because each circuit would be correct for that appliance wheras at the moment who knows .

 

[flying haggis]

Thank you flying haggis, but can they share the same terminal block?

yes thats what connectors like this are for
https://www.google.com/imgres?imgur...hUKEwjhtLzo5OXwAhUKaBoKHRW2BTgQMygNegUIARCAAw

 

[porker]

From the On site guide...

H4 Cooker circuits in household and similar premises
The circuit supplies a control switch or a cooker unit complying with BS 4177, which may incorporate a socket-outlet. The rating of the circuit is determined by the assessment of the current demand of the cooking appliance(s), and cooker control unit socket-outlet if any, in accordance with Table A1 of Appendix A. A 30 or 32 A circuit is usually appropriate for household or similar cookers of rating up to 15 kW. A circuit of rating exceeding 15 A but not exceeding 50 A may supply two or more cooking appliances where these are installed in one room. The control switch or cooker control unit should be placed within 2 m of the appliance, but not directly above it. Where two stationary cooking appliances are installed in one room, one switch may be used to control both appliances provided that neither appliance is more than 2 m from the switch. Attention is drawn to the need to provide selective (discriminative) operation of protective devices as stated in Regulation 536.3.

 

[HappyHacker]

It can also depend on the hob/oven manufacturers instructions regarding overcurrent protection on the supply. NICEIC are not the ultimate authority and occasionally give controversial advice. As has been said you need to be told what regulation it contravenes. It is quite a common question and the answer is often "it depends ..."

Edit: The on site guide is a guide and does not cover every eventuality. It is down to the designer to justify any design decisions and sign it off.

 

[Spectric]

The legal route is exactly the course I'm considering, but I before entering a fight, I need to know my chances of winning.

A very hard question to answer and a definative answer can only be given if your instalation was inspected, cannot be done online or remotely because for a legal challenge either someone has been injured through this installation so you are claiming negligence or you need a written report from an electrician to support a claim for a substandard or dangerous instalation.

The one point to bear in mind is that for any change in electrical conductor size then there should be a protective device unless protection is provided for the smaller conductor size..

 

[Spectric]

Two electricians and two appliance installers

It they are electricians then why are you questioning their advice, but I would question advice from appliance installers, what are their qualifications!

 

[Sideways]

BS 7671 is the definitive document. Everything else is just interpretation of it and therefore open to argument.
The on site guide effectively simplifies and interprets the regs to make for quicker, easier understanding "on site". A designer with the depth of knowledge of the regs and experience may design a solution that is safe and totally compliant with BS7671 but more cost effective than recommended by the on site guide. The OSG tends to employ simplifications with a little extra fat in it's recommendations so the designer doesn't have to do as much math to justify every element of their design.
As a trade body for a lot of sparks, the NICEIC are worth listening to. They play a role in trying to figure out best practice / interpreting the ambiguous parts of BS7671 on behalf of their members. As do NAPIT. Both employ some experienced people to try and do that. They don't get it right every time and often advice evolves over time, but worth listening to.
Lastly. There's a hierarchy in electrical quals. If your guys have the City & Guilds level 3 that allows them to do initial and periodic testing of installations without someone else signing off for them, then that's a good start. But the qualification in design is higher level, harder and a lot of domestic electricians don't have that as you can belong to a self cert scheme and do domestic work without it.
You need to know the quals of the various people who you are talking to, what section of BS7671 they are referencing and how they are interpreting that.

 

[Inspector]

Just curious. We have a national electrical code but provinces and cities can set higher standards. Does the same apply to you? Might you live in a higher standard area and that is why the wire tuggers are telling you no?

Pete

 

[Sandyn]

yes thats what connectors like this are for
Google Image Result for https://www.tlc-direct.co.uk/Images/Products/size_3/AA45DCOPX.JPG

If you were using a commercially supplied device (such as above) to connect the appliances, I would push the question back to the supplier. They make them to meet the relevant standards, so should be OK This assumes you meet all the wiring size/distance/height requirements. If you have cobbled something together using a large terminal block, then that is not OK. Even though electrically it's the same. it doesn't meet the requirements of standard BS 5733, so doesn't comply with BS 7671. Appendix 1.

 

[sirocosm]

Not sure if this helps, but this is from appendix H of the BS-7671 On-site guide (2018):

H4 Cooker circuits in household and similar premises
The circuit supplies a control switch or a cooker unit complying with BS 4177, which may
incorporate a socket-outlet.
The rating of the circuit is determined by the assessment of the current demand of the
cooking appliance(s), and cooker control unit socket-outlet if any, in accordance with
Table A1 of Appendix A. A 30 or 32 A circuit is usually appropriate for household or
similar cookers of rating up to 15 kW.
A circuit of rating exceeding 15 A but not exceeding 50 A may supply two or more
cooking appliances where these are installed in one room. The control switch or cooker
control unit should be placed within 2 m of the appliance, but not directly above it.
Where two stationary cooking appliances are installed in one room, one switch may be
used to control both appliances provided that neither appliance is more than 2 m from
the switch. Attention is drawn to the need to provide selective (discriminative) operation
of protective devices as stated in Regulation 536.3.

Edit: Just noticed porker already posted that, but can confirm this is a cut/paste of that document.

 

[Sideways]

Just curious. We have a national electrical code but provinces and cities can set higher standards. Does the same apply to you? Might you live in a higher standard area and that is why the wire tuggers are telling you no?

Pete

No.

 

[Inspector]

No.

Thanks.

Pete

 

[MikeJhn]

Worth noting in a worse case scenario, modern Double Fan Ovens can draw over 40amps when on intensive mode and a modern Induction hob can also draw over 40amps.