Kitchen ring mains, cable routing

[Catalin]

I am converting a room into a kitchen. I have to install a ring mains, a (radial) circuit for the oven, and a separate radial circuit for the fridge/freezer. I know this will have to be notified. My questions are about routing the cable for the ring.

1. Can I route some of the cable on the surface of the wall behind the cabinets, rather than buried into the wall?

1a. If I can route cables on the surface of the wall, am I right in thinking that they don't have to be in safe zones? Those apply only to buried cable (and only if less than 50mm deep).

2. Can I have a FCU that's part of the ring mains inside a cabinet, on the inner side of the cabinet, in a surface mounting box, with the cables in mini-trunking going through the back of the cabinet? The FCUs feed single, unfused, inaccessible outlets where built-in appliances connect (or flex connection plates, where the appliance comes with pigtails rather than a 13A plug). There would be three cables to each FCU: two from the ring, one for the load.

2a. If I can't have a FCU that's part of the ring mounted inside a cabinet, what about one that's a spur?

2b. If I can't have a FCU mounted in a cabinet at all, what are other ideas about where to place them so that they are not immediately visible? (I wanted them in plain view, but my wife objected when I told her we would have six of them: cooker hood, gas hob (for ignition), plinth heater (hydronic), dishwasher, built-in microwave oven, built-in fridge-freezer).

Also, can you tell me about the notification process? How do the inspections work, and what happens if they find something that's not satisfactory? Are the inspectors typically helpful, or do they try to discourage DIYers like me?

 

[Veglen]

1. Can I route some of the cable on the surface of the wall behind the cabinets, rather than buried into the wall?

Yes.

1a. If I can route cables on the surface of the wall, am I right in thinking that they don't have to be in safe zones? Those apply only to buried cable (and only if less than 50mm deep).

IMO No! The safe zones will still apply because the units will be fixed to the building structure. Therefore, becoming part of the structure and cable will not be visible!

2. Can I have a FCU that's part of the ring mains inside a cabinet, on the inner side of the cabinet, in a surface mounting box, with the cables in mini-trunking going through the back of the cabinet?

Yes, although some would disagree. If the unit is fixed to the wall then it will become part of the structure. Otherwise the argument of safe zones behind such units wouldn't stand up!

2a. If I can't have a FCU that's part of the ring mounted inside a cabinet, what about one that's a spur?

You can have a spur provided the the cable joint off the ring is accessible for inspection.

2b. If I can't have a FCU mounted in a cabinet at all, what are other ideas about where to place them so that they are not immediately visible?

Behind the appliance if not built in, or on the wall below and behind the units at plinth level or even in an adjacent room in a module grid switch plate?

The cooker isolator should be within 2 metres of the appliances and easily accessible and IMO preferably on view!

As you are aware you must notify this type of work to LABC. If you are competent to do the work there shouldn't be a problem. However, they will want to inspect your first fix. i.e cable runs, safe zones, accessory point locations, etc,etc!

Make sure they know in advance that they are going to have to test and inspect this installation for you when it is complete!

Are the inspectors typically helpful, or do they try to discourage DIYers like me?

Only if they feel that you are not competent to do this type of work!

Good luck

V

 

[Catalin]

Thank you for your answer, very helpful.

It won't take much extra cable to run the surface wiring in the safe zones, and no extra work, so I'll do it that way.

What exactly is a first fix? I plan to do these steps, in this order:
1. Dig holes for mounting boxes.
2. Dig trenches for buried cable.
3. Drill holes in floor joists along the path to the consumer unit.
4. Run cables for the new circuits, without connecting them to the consumer unit or anything else just yet.
5. Fix the mounting boxes in their holes, and make good around them.
6. Cover the buried cable with plaster.
7. Clip exposed cable to wall.
8. Install kitchen cabinets.
9. Install mounting boxes in cabinets, thread cables through holes in the backs of the cabinets, install mini-trunking.
10. Install all sockets and FCUs.
11. Test the circuit. I have an adequate ohmmeter for continuity and resistance measurements, but I'll probably have to hire an insulation resistance meter for the 500 volt test at this point. The circuit is short enough for the current of a live-earth fault to trip a standard MCB within milliseconds -- and it's on the protected side of the RCD in the split-load consumer unit.
12. Turn off power, connect the circuit to the consumer unit, turn power back on.

Does this make sense, and if yes, where in my schedule will the LABC want to inspect this?

 

[griggs]

Points 1-5 & 7 as 1st fix, inspector will need to see these as well as explain point 9

Point 10 2nd fix

You will need more than an ohmmeter to carry out the necessary testing. Are you aware of the tests you need to carry out?

Will building control accept your test results - thought they get someone in to do the testing as part of the building control notice?

 

[ColJack]

here's a question..

do you still have to notify if the room isn't a kitchen when you do the electrical work? ( as part of the kitchen notification thing, not for general addition of circuits and such, i know that.. )

 

[Catalin]

do you still have to notify if the room isn't a kitchen when you do the electrical work?

I'm playing it safe. And I'm adding a new circuit, which is notifiable at any rate.

Will building control accept your test results - thought they get someone in to do the testing as part of the building control notice?

I have no idea, that's one of the things I would like to find out. I'll probably call them and ask...

While we're on the subject, can I throw in as many changes as I want on one Notice? I need to fix the ring mains in the bedrooms (it's a mess, it has spurs on spurs on spurs, and it might not even be a ring anymore, and one of the sockets in the old kitchen downstairs is on the same circuit as the bedroom sockets -- at least it's all on a 16A MCB, so it's not very dangerous), the lighting circuit in the old part of the house (no earth anywhere), run new central heating controls (I want zones, so I'm converting from Y plan to "S+" plan), move some pipes and radiators, and replace the hot water cylinder and the loft tank (I'll get a contractor to remove the asbestos tank when I'm done putting in the new plastic one). If I put all these and the kitchen circuits on one notice, will they want to inspect all of them at once, or can I call them as often as I need as I get to work on each of them? I'm doing this during weekends and mornings (I work evenings), so it's going to take a while -- and I would like to avoid the expense of having to notify each change on its own.

 

[DESL]

Speak to your LABC and explain what you are doing - you may find them helpful.