help me wire this please

[shocksl]

Hey guys


As some of you know I study at York College. I am working on an assignment exam, Which I need some help with.

Fixed appliances:

• 12k W electric cooker with induction hub (no socket)
• 300W extractor over cooker
• 7 KW electrical central heating and hot water boiler.

Building construction :

• Outer walls - brick with wood cladding, insulated cavity
• Inner walls : plasterboard dot and dabbed onto lightweight blockwork
• Floors: laminate flooring on 50mm concrete seed.
• Ceiling lasterboarded through with acess hatch into fully accessible loft void above. Ceiling 2.3m above finished floor level.
• Loft insulation : this 250mm thick and cables are to be clipped to joist or lay on plasterboard.

Electric supply

• 230v , TNCS, with ZE and PFC at 0.3 ohms and 0.77ka
• Amb temp 25 degrees

This is for a 2 bedroom bunglow and I need to wire it.





I have decided the accessories will include the below and with FSU for boiler, and cooker:


2 bedrooms –ill put 1 x light in each room. And 3 x double sockets each room

1 onsuite room – so 1x light – no sockets

Small hallway – 1 xlight and 1 double socket and 1 smoke alarm

Bathroom has sections so 2x lights. 0 sockets

Utlity room – 1 x light plus 2 x double sockets

Kitchen 1 xlight. Plus about 7 xdouble sockets and 2 x single sockets.

Large diner and lounge room integrated.. so therefore 2 x lights plus 5 x double sockets



If you think I should add more please let me know.



What will be the best way to wire this ? since theres concrete under laminated flooring, . I am thinking of taking the cables from the consumer unit and take the wire up to the loft clip to joists and drop to the nearest socket for the circuit and then back up the wall clip up the joist and come down again into the next socket. And repeat until the sockets are complete. For the ring curcuits. Take the wire back again same way


In terms of lights can I just lay them over the plastboard? And it doesn’t matter how they go as theres no safe zone etc. is this correct? So in affect I can just go up the consumer unit abover th plasterboard just go in diagnels if I have to get the light and switches?

once Ive done this I will do all the calcs required.



Any advice would be greatly applreciated. I am more than happy to discuss further,.



thanks

 

[richy3333]

Hi.
What is the assignment question - sorry you haven't specified this. Presumably you need to do cable calculations?

What are you studying at York college?

What reference material do you have? - BS7671?

I think if you try and answer the assignment question members will jump on to help with advice and pointers etc

 

[littlespark]

Diagonal runs? No.

And what do you mean no safe zones?


Might need more than one smoke detector.

Extractor fan in bathrooms?

Appliance switches in kitchen?

How many of each circuit? 2 or 3 rfc’s… 1 just for kitchen. 2 or 3 lighting circuits?

12kW for cooker? That’s massive.

 

[shocksl]

Hi.
What is the assignment question - sorry you haven't specified this. Presumably you need to do cable calculations?

What are you studying at York college?

What reference material do you have? - BS7671?

I think if you try and answer the assignment question members will jump on to help with advice and pointers etc

I'm ok with the cable calcs. That will be after ive workd out how i will wire the bungolow. Ive wrote it in the last paragraph.. . ref is BS7671

So basically I have a layout diagram and I need to wire it up and put accessories etc on it. Which I have stated in the first post.

Once I get that bit right I can then move onto doing the calcs.

 

[shocksl]

Diagonal runs? No.

And what do you mean no safe zones?


Might need more than one smoke detector.

Extractor fan in bathrooms?

Appliance switches in kitchen?

How many of each circuit? 2 or 3 rfc’s… 1 just for kitchen. 2 or 3 lighting circuits?

12kW for cooker? That’s massive.

I propose

1 radial for cooker
1 radial circuit for boiler
Kitchen has 1 final ring
Rest of the bunglow on 2nd ring
2 lighting circuits to avoid voltage drop.

Yes 12kw is massive but it's part of the assignment brief.

Good shout to add the those to my list .

 

[shocksl]

This is how the layout looks. I haven't put all the accessories etc on it yet

 

[richy3333]

Id say that the plan looks ok. In the kitchen you have the light switch behind the door. Don't know about England and Part pee but in Scotland light switches have to be outside the bathroom.

I can't help much more as I'm still confused as to what you want help with.

 

[shocksl]

Id say that the plan looks ok. In the kitchen you have the light switch behind the door. Don't know about England and Part pee but in Scotland light switches have to be outside the bathroom.

I can't help much more as I'm still confused as to what you want help with.

How to wire it to the different cables . So how do I get the different cables to all the different accessories. That's something I've never done. So I'll find out the length of cables for each circuits so I can do my cable cals which I'm comfortable with.

 

[mainline]

Diagonal runs? No.
And what do you mean no safe zones?

The cables wouldn't be concealed.

 

[plugsandsparks]

Agree - drop down from loft, however for sockets you can go horizontal once you have dropped down, also there may be opportunities to place sockets on either side of walls to reduce cable runs.

Your cooker cct is going to be a challenge for cable and local isolator so allow space for a fat cable and huge isolator, lol

 

[mainline]

I wouldn't use 3 ring finals, I would radial the bedrooms.

Socket on side of beds, usb ?

More lights in kitchen, cabinet under lights ? Cooker hood ?

Bathroom shaver socket/ mirror light ? Fan ?

 

[shocksl]

I wouldn't use 3 ring finals, I would radial the bedrooms.

Socket on side of beds, usb ?

More lights in kitchen, cabinet under lights ? Cooker hood ?

Bathroom shaver socket/ mirror light ? Fan ?

Hi

As its for an assignment I don't want to add too many things so I don't over complicate things for myself when I do the cable calcs etc. It's not for real life. I think their concerned if I get the main things in and can work it all out at the end.

Maybe I'll add a fan to the bathroom. Would that just spur off the light ?

So are you saying 1 radial covering both bedroom rooms. 1 radial for cooker, 1 radial for boiler. 1 ring for lounge/diner and hallway ?

 

[shocksl]

Agree - drop down from loft, however for sockets you can go horizontal once you have dropped down, also there may be opportunities to place sockets on either side of walls to reduce cable runs.

Your cooker cct is going to be a challenge for cable and local isolator so allow space for a fat cable and huge isolator, lol

So would you say drop down from loft to a room go horizontal for all the sockets ie 2 double sockets in bedroom. Then go back up to the loft and drop down into the next room ?

 

[mainline]

Hi

As its for an assignment I don't want to add too many things so I don't over complicate things for myself when I do the cable calcs etc. It's not for real life. I think their concerned if I get the main things in and can work it all out at the end.

Maybe I'll add a fan to the bathroom. Would that just spur off the light ?

So are you saying 1 radial covering both bedroom rooms. 1 radial for cooker, 1 radial for boiler. 1 ring for lounge/diner and hallway ?

If the fan is a timed one then it would require a 3 pole isolator, if not then a dp fused switch would do.

Yes, off the bathroom lighting circuit.

 

[shocksl]

If the fan is a timed one then it would require a 3 pole isolator, if not then a dp fused switch would do.

Yes, off the bathroom lighting circuit.

Thank you would that come off the light circuit ?

Also can you tell me how would it benefit having more radials than rings please ?

 

[mainline]

Thank you would that come off the light circuit ?

yes

Also can you tell me how would it benefit having more radials than rings please ?

Selectivity.

 

[plugsandsparks]

So would you say drop down from loft to a room go horizontal for all the sockets ie 2 double sockets in bedroom. Then go back up to the loft and drop down into the next room ?

If the layout suits, (i have not looked at the schematic) its possible to drop down once, pick up all the sockets you can horizontally only going back up for obstacles like doors. Also you may be able to pick up the next room by going through the wall and just keep going only going back up if you need to. If say you are going for radials, which i would do for most of the sockets (kitchen / utility probably not) then if you plan it nicely there is just one drop which will save a huge amount of cable and reduce how many opportunities for someone to hang a picture in the wrong place, lol

 

[westward10]

yes

Selectivity.

It has nothing to do with selectively.

 

[shocksl]

yes

Selectivity.

Thank you

So would it be suffice to have

If the layout suits, (i have not looked at the schematic) its possible to drop down once, pick up all the sockets you can horizontally only going back up for obstacles like doors. Also you may be able to pick up the next room by going through the wall and just keep going only going back up if you need to. If say you are going for radials, which i would do for most of the sockets (kitchen / utility probably not) then if you plan it nicely there is just one drop which will save a huge amount of cable and reduce how many opportunities for someone to hang a picture in the wrong place, lol

Lol this has helped alot !!

So to get an understanding I'll take a radial from the CU. Go up to the loft. I can clip direct on the joists or lay on plaster as it says on the assignment brief. So does it matter how I get the cable when its in the left to the required room. So for example if I take I take it up from CU I get in the loft and I need to get into bedroom 2 .. do I need to go arounf the external walls. Or cut straight through in sort of diagonal. I've never done it life lol

 

[plugsandsparks]

In the loft how you get from the CU to a drop will depend. from CU , chances are that the ceiling / roof joists span across the shortest wall to wall distance, if so you can simply clip to these joists, that will put you above the lounge, from there you can take a route to drop down to the sockets in the far side of the bungalow. There are no right / wrong routes in the loft. Need to be clipped, preferably above the insulation but not mandatory as you can de-rate for that. Have a go on the drawing and post...

 

[shocksl]

In the loft how you get from the CU to a drop will depend. from CU , chances are that the ceiling / roof joists span across the shortest wall to wall distance, if so you can simply clip to these joists, that will put you above the lounge, from there you can take a route to drop down to the sockets in the far side of the bungalow. There are no right / wrong routes in the loft. Need to be clipped, preferably above the insulation but not mandatory as you can de-rate for that. Have a go on the drawing and post...

Thank you so much that has had made alot of sense. I appreciate you giving your time.


I'm going to have a go this afternoon to draw it on.

The only other considerations I really need to make is installation reference method.

I'm not sure whether inside the walls it needs to be enclosed in a conduit or not.

In the loft as there is 250mm insulation. I will be clipping sides of the joists. Given that a standard joists is under 230mm . It will be affected so I cable calcs I'll include that factor. However i don't think it needs any conduit or trunking at this stage in the lift.

Below is a reminder of the building structure.



Building construction :

Outer walls - brick with wood cladding, insulated cavity
Inner walls : plasterboard dot and dabbed onto lightweight blockwork
Floors: laminate flooring on 50mm concrete seed.
Ceiling lasterboarded through with acess hatch into fully accessible loft void above. Ceiling 2.3m above finished floor level.
Loft insulation : this 250mm thick and cables are to be clipped to joist or lay on plasterboard.

 

[mainline]

Thank you so much that has had made alot of sense. I appreciate you giving your time.


I'm going to have a go this afternoon to draw it on.

The only other considerations I really need to make is installation reference method.

I'm not sure whether inside the walls it needs to be enclosed in a conduit or not.

In the loft as there is 250mm insulation. I will be clipping sides of the joists. Given that a standard joists is under 230mm . It will be affected so I cable calcs I'll include that factor. However i don't think it needs any conduit or trunking at this stage in the lift.

Below is a reminder of the building structure.



Building construction :

Outer walls - brick with wood cladding, insulated cavity
Inner walls : plasterboard dot and dabbed onto lightweight blockwork
Floors: laminate flooring on 50mm concrete seed.
Ceiling lasterboarded through with acess hatch into fully accessible loft void above. Ceiling 2.3m above finished floor level.
Loft insulation : this 250mm thick and cables are to be clipped to joist or lay on plasterboard.

Also, don't forget to take into account reg 521.10.202

 

[mainline]

It has nothing to do with selectively.

Selectivity refers to the ability of a system to isolate a fault to a specific section, minimizing the outage to only that section and not the entire system.


Selectivity Previously known as discrimination, selectivity is the ability of the protective device to operate in preference to another device, which is in a series connection configuration. For correct device coordination, short-circuits, overcurrents and residual currents will need to be considered.

• In a radial circuit, the fault current is limited to the specific circuit where the fault occurs, as there's only one path for the current to flow. This makes it easier to isolate the fault and restore power to other parts of the system without disrupting the entire network.
• Easier Coordination of Protective Devices:
  When designing a radial system, it's easier to coordinate the tripping characteristics of circuit breakers or fuses to ensure selectivity. This means that a fault on a downstream circuit will trip the circuit breaker on that specific circuit, while upstream circuit breakers remain intact.