first domestic rewire, opinions please.

[Richard Sutcliffe]

My concern with a 32a ring with 60a supply is that if the shower is on pulling 33a and ring is at near max then the main fuse will go, where as on a radial it would trip the mcb instead. The kitchen has washer, fridge freezer and usual toaster, kettle and microwave. The cooker is all gas which I intend on keeping. No intention of wiring a cooker circuit again due to supply being so small.

The idea of smoke's on the light circuit makes sense, I just thought they had to be on a dedicated supply.

Are kitchen extractors wired the same as bathrooms? I need to find a suitable place for that with kitchen being Io the basement.

 

[SPECIAL LOCATION]

My concern with a 32a ring with 60a supply is that if the shower is on pulling 33a and ring is at near max then the main fuse will go, where as on a radial it would trip the mcb instead. The kitchen has washer, fridge freezer and usual toaster, kettle and microwave. The cooker is all gas which I intend on keeping. No intention of wiring a cooker circuit again due to supply being so small. The idea of smoke's on the light circuit makes sense, I just thought they had to be on a dedicated supply.

Are kitchen extractors wired the same as bathrooms? I need to find a suitable place for that with kitchen being Io the basement.

Extremely unlikely to go IMHO....

Diversity being the key word here!..

There are millions of homes all around the UK with..

32A rings

32A cookers

40A showers..

etc...

all off 60A main cut out fuses....

Go back and check in your books how much current is needed to blow a 60A HRC cut out fuse?



Where as...

Kitchen with all those appliances on a radial is going to put a excessive amount of strain on the first leg of 2.5mm from the fuse box..

either 4.0mm if radial or 2.5mm ring ..

Personally I would be doing 2.5mm ring in a kitchen..



Anyone considering a radial for kitchens/utility's is a bit daft IMHO, share & distribute the loading around the cable..

keep it working longer!



{Sounds like the course you took missed out on a few basics of circuit design and electrical science IMHO :_| }

 

[Sharpend]

I don't drink in all honesty AndyGuinness

I guess you must be experiencing the "virtual" pi**ed feeling.

 

[alpha spark]

As special location says your only going to use the same ammount of appliances whether you wire it has a ring or a radial

 

[SPECIAL LOCATION]

As special location says your only going to use the same amount of appliances whether you wire it has a ring or a radial

And they are all unlikely to be drawing full power at the same time....

i.e.

Much of a washing machine cycle is only spinning the drum around...

NOT heating water....

Diversity is the thing that trips up loads of inexperienced sparks...

when they assume everything is running full whack simultaneously for over 50% of the time...

 

[Manator]

Extremely unlikely to go IMHO....I agreeDiversity being the key word here!.. Not used by most it would apprear

There are millions of homes all around the UK with..

32A rings

32A cookers

40A showers..

etc...

all off 60A main cut out fuses.... So would not change on a new board!

Go back and check in your books how much current is needed to blow a 60A HRC cut out fuse?



Where as...

Kitchen with all those appliances on a radial is going to put a excessive amount of strain on the first leg of 2.5mm from the fuse box..

either 4.0mm if radial or 2.5mm ring ..

Personally I would be doing 2.5mm ring in a kitchen..



Anyone considering a radial for kitchens/utility's is a bit daft IMHO, share & distribute the loading around the cable..

keep it working longer!



If I did do domestic I would put all main appliances on individual radials, but I doubt I would get any work, a ring offers the potential to share the load around the circuit.

{Sounds like the course you took missed out on a few basics of circuit design and electrical science IMHO :_| }

This is always a problem with design, if you keep it simple and read the regulations more it soon becomes apparent why some regulations are in force. The science behind any electrical installation is the same, and the diversity given in the books are a guide for those who do not design their own diversity. Its amazing if you look at the curves for a given fuse just how long it would take to blow.

 

[Richard Sutcliffe]

Ring is sounding a better idea now you've got me thinking a bit more about it.

Would you put 1st floor on the ring aswell as I planned to do with the radial or run that as a seperate radial?

I did the c&g 2330 level 2 and 3, which I feel has taught me a lot, however I know experience means a lot hence why I asked on here.

THis may sound a stupid question, but what makes a ccu a good one? LIke the hager ones you mentioned.

 

[Zeespark]

You won't go far wrong with Hager, I have found them to be the most adaptable of the lot, and if needs be, finding replacement parts for them is a doddle, dont rely on the built in spirit level though, its carp

AndyGuinness

 

[Cirrus]

Ahem, did I not explain the benefits of a ring???

As for C/U - the Hager 5/5 split boards are great - I pay

 

[Manator]

Richard, the design of any installation is down to cost and efficiency, with a little added what if?

I never understand why some install ring circuits to bedrooms for instance, given the amount of power demanded radials are more cost effective.

Just have a look now at you connected electrical devises in your own home, lets take the living room as an example. TV on? well there is no more than 5 amp, music station playing? well thats another 5 amp or maybe even 3amp. Electric fire? OK lets give that 10 amp,aquarium? another 10 amp at most for a marine setup, 5 amp for some random goldfish.

Lets add all them up and we have 30 amp at most if all on at the same time. I bet the actual figure would be around 18amp, or less.

Lets take a bedroom with a 3amp table lamp a 5 amp TV and you get to start to think about just how little energy all electrical items really do use.

Put a clamp meter on your supply cable and turn everything on that you can, you will be amazed at the results.

 

[NozSpark]

Richard, the design of any installation is down to cost and efficiency, with a little added what if?I never understand why some install ring circuits to bedrooms for instance, given the amount of power demanded radials are more cost effective.

Just have a look now at you connected electrical devises in your own home, lets take the living room as an example. TV on? well there is no more than 5 amp, music station playing? well thats another 5 amp or maybe even 3amp. Electric fire? OK lets give that 10 amp,aquarium? another 10 amp at most for a marine setup, 5 amp for some random goldfish.

Lets add all them up and we have 30 amp at most if all on at the same time. I bet the actual figure would be around 18amp, or less.

Lets take a bedroom with a 3amp table lamp a 5 amp TV and you get to start to think about just how little energy all electrical items really do use.

Put a clamp meter on your supply cable and turn everything on that you can, you will be amazed at the results.

Jeez Manator,, you must have some juice guzzling bits and bobs around your house:O

For instance:-

Table lamp---- 60W

Aquarium heater ----200W

Aquarium pump ----20W

TV (and I'm talking my 36" CRT one here) 400W max

 

[Manator]

Jeez Manator,, you must have some juice guzzling bits and bobs around your house:OFor instance:-

Table lamp---- 60W

Aquarium heater ----200W

Aquarium pump ----20W

TV (and I'm talking my 36" CRT one here) 400W max

I just quoted the fuse requirements, not the actual usage, that's why I said you would be surprised at the readings if you used a clamp meter on the incomer.

 

[NozSpark]

I knew you were TBH

But you are right; if you actually sit down and think about the useage you'll soon realise there is no point of having a 32A ring in the living room or bedrooms, kitchen/utility yes though

 

[Richard Sutcliffe]

Finally managed to get online again to have a more detailed look into your points. It is also the first time of trying to do an 'advanced reply' on the forum so I apologize if this comes out a large pile of code.

On top of which, Hager boards are the dogs chopper. As are Aico smokes. Get hold of Aicos Contractors Handybook, it tells you all you need to know about smoke systems in domestic.

I have applied for a copy to be sent out to me for a look. I have returned the smokes I originally bought as I realized they didn't have a battery backup. Are the radio linked Aicos worth fitting as opposed to a 3 core link running over 4 floors?

Comes under Part P obviously. Presuming this "other spark" is Part registered then he/she have to be careful on the "signing off".

Yes he is part P. However after talking to NAPIT today it is more likely I will inform Local Authority I have done the work and that it will be used as one of my jobs for my NAPIT assessment and then certified myself.

Also make sure that shower circuit is method C if you're using 6mm.

After looking again at installation methods I think I may be wrong if I use 6mm. Can someone clarify if method C includes being buried under plaster? The majority of the circuits are being run under floorboards (is this 'in a ceiling, appx 4, 7.2?), clipped to masonry and skimmed over with plaster, and run up the side of a door frame to get to the upper floors (In what I would class as Ref 40?)

Main points for me have already been covered1. I'd be pulling in a ring for the kitchen

Radials fine for elsewhere

2. I'd be putting the smokes on with a lighting circuit to avoid them being turned off in a year or two when the beeping starts

3. No mention of cooker circuit?

Depending on run I would be inclined to run one for future use?!?

I have decided to pull a ring in, at the end of the day it was only an extra 3m or so of cable to run it back. Basement (Kitchen) and ground floor power both to be on RCD2 as a 32A Ring for the kitchen and 20A radial for ground floor (Lounge) with 1st and 2nd floor power (bedrooms) on RCD1 as a 20A radial (as long as Volt drop works out fine when I get clarification over my ref methods as stated above), with lighting to each floor on opposite RCD's to power.

Smokes are to go onto lighting circuit now, makes sense when the idea was mentioned. Thanks.

Might put a cooker circuit in if I have enough cable left over.

Ahem, did I not explain the benefits of a ring???As for C/U - the Hager 5/5 split boards are great - I pay

 

[Manator]

Your reply works fine.

There are a lot of questions there Richard, I would suggest you read over and over books like the onsite guide and any other books that include installation design. The reference methods for cable installation is used for de rating purposes so you can correctly assess its suitability for the expected supply. Any cable de rated should be done so for the worst case possible unless the length is so short that it would be negated by other factors.

A four storey dwelling would require a fire corridor offering at least 30 minutes fire protection, this would involve an early warning system to be installed, but would not necessarily require a fire control panel to be installed. It would however require a detector and sounder (combined in most domestic smokes) to be fitted on either side of the fire doors along the fire route.

 

[Richard Sutcliffe]

I would of split it up into different posts but didn't want to forget anything. I have been going over the regs book with reference to instalation methods but cannot find any mention of plaster over clipped direct, or anything that matches that description. Reference method C looks the closest but if it doesn't include plastering over surely the plaster would retain heat and therefore a derate of cables would be required? Is there any books someone could recommend for basic installation design? I want to start as I mean to go on, I don't want to 'assume' anything and get it wrong.

 

[PC Electrics]

Cable clipped to brick or block and buried in plaster (or behind a dot & dab plasterboard panel) = ref method C

---------- Post Auto-Merged at 21:29 ---------- Previous post was made at 21:26 ----------

After looking again at installation methods I think I may be wrong if I use 6mm. Can someone clarify if method C includes being buried under plaster? The majority of the circuits are being run under floorboards (is this 'in a ceiling, appx 4, 7.2?), clipped to masonry and skimmed over with plaster, and run up the side of a door frame to get to the upper floors (In what I would class as Ref 40?)

err, watch your permitted zones!! This doesn't sound like such to me!

---------- Post Auto-Merged at 21:30 ---------- Previous post was made at 21:29 ----------

My local Edmundsons and Denmans are both excellent

---------- Post Auto-Merged at 21:32 ---------- Previous post was made at 21:30 ----------

As you're rewiring anyway I'd stick with hard wiring your smokes. Radio bases are

 

[Richard Sutcliffe]

******... too busy thinking about cable runs, installation methods and volt drops and forgot about permitted zones. What is the 'done' thing about running cables from 1 floor to another? At present it would run vertical with the light switch on the ground floor so no problem, but then it goes through the bathroom vertically in a channel covered with architrive (sorry for the spelling mistake) in the middle of the wall, no sockets or switches to run in its zone.

I think I may try Edmundsons this week then. Need to get my smokes and heat alarms so I'll pop down and spend a penny or two.

 

[Doc Hudson]

Cable clipped to brick or block and buried in plaster (or behind a dot & dab plasterboard panel) = ref method C err, watch your permitted zones!! This doesn't sound like such to me!

If you want to verify PC's comment Richard in the big list in appendix 4 of BS7671, the schedule of installation methods number 57 is single or multi core cable direct in masonry, (method C) which basically includes cables surrounded by bricks and plaster and as PC highlights is this cable up the door frame surface or buried? if it is buried I would think it would be outside of safe zones.

Doc H.

 

[PC Electrics]

It is a recommendation of BS5839t6 that smokes are not protected by the same RCD as sockets. This is not a regulation though, so you could go ahead as above. I'd recommend a hi integrity board so you can put one lights/smokes and one socket circuit (kitchen) on an RCBO each.

I have decided to pull a ring in, at the end of the day it was only an extra 3m or so of cable to run it back. Basement (Kitchen) and ground floor power both to be on RCD2 as a 32A Ring for the kitchen and 20A radial for ground floor (Lounge) with 1st and 2nd floor power (bedrooms) on RCD1 as a 20A radial (as long as Volt drop works out fine when I get clarification over my ref methods as stated above), with lighting to each floor on opposite RCD's to power.Smokes are to go onto lighting circuit now, makes sense when the idea was mentioned. Thanks.

So you'll end up with smokes protected by an RCD which also protects sockets??