KITCHEN RING. Just COOKER, HOB & EXTRACTOR?

[srands]

Hi quick question about what is common practice when wiring KITCHEN RINGs for your typical 4 bedroom house:

i) KITCHEN to include just COOKER, HOB & EXTRACTOR?

ii) OR i) + INCLUDE all other larger appliances (Washer, Dryer, Dishwasher, Fridge and Freezer), as well?

iii) OR i+ii INCLUDE all WORKTOP LEVEL sockets (Microwave, kettle, toaster, sandwich toaster, deep fat fryer, etc), as well?

iv) UNLESS just i), then all other KITCHEN APPLIANCES included with GROUND FLOOR SOCKET RADIAL?

Cheers

Stephan

 

[poheZ]

Think about this the fuse in the plug will only protect the cable going to the appliance it will not protect the 2.5mmT&E this would be protected by the mcb or fuse at the board unless you fused the dp switch you get fuse units for grids if the mcb or fuse was 32A this wouldn't be great practice to just have a 2.5mm T&E on it I would down rate it to a max 20A unless on a ring of course

no your wrong. The fuse is simply upstream of the cable.

In any case a 4mm radial is way ott. Have a look at most appliances and what they consume. A 20 amp radial would suffice to run 3/4 appliances

 

[Smugley]

I don't disagree that a smaller CSA would still be safe. Had this discussion on here last year and had divided opinions again, so in the end chose the safest possible approach. Also didn't have spec of appliances at first fix stage and wanted to allow 2kW per socket - total of 34A with no diversity. Just erring on the safe side, that's all.

 

[SPARTYKUS]

I wired a kitchen ring in 4mm2 (yes a RING!) once. and only once. Because that is what the customer paid me to do. What a pain. The Zs figures were great, it will never be overloaded, etc etc a feat of over engineering but the number of times I had to wrestle three cables into the back of a GET flat plate nickel pewter thingy .... nightmare, it is possible but it was so tight I hardly needed to screw (eh-hem).

The chap had spare rolls of it and insisted on a ring so what could I do !

 

[jmtisme]

no your wrong. The fuse is simply upstream of the cable.

In any case a 4mm radial is way ott. Have a look at most appliances and what they consume. A 20 amp radial would suffice to run 3/4 appliances

No I am not wrong the fuse in a plug will only protect the appliance if the fuse/mcb at the consumer unit protects the fixed wiring

 

[Amp David]

If done correctly, spurring in 2.5 should never become overloaded anyway. Thats why its allowed or am I wrong

 

[srands]

OK some irrelevant/nonsence chit chat here, you would think you're trying to confuse somebody who knows sweet FA!
I'll some up the useful comments made so far about KITCHEN RING:

KITCHEN RING includes: COOKER, HOB and other large applainces, fridge, freezer, dishwasher, washing machine & dryer, etc.
KITCHEN RING excludes: WORKTOP level sockets, these are to be included typically in GRND FLOOR SKT RADIAL.

And on the subject of RINGS lets talks about RING AMPAGES, what are the approx RING AMPAGES of:
1mm, 2.5mm, 4mm, 6mm, 10mm and 16mm skt wire?

It is a simple question, that has a simple answer :
A very approximate RING AMPAGE per different skt wire diameter!

OBVIOUSLY IEE AND SKT WIRE MANUFACTURERS ARE VAGUE ABOUT SPECIFYING RING AMPAGE MAXIMUM VALUES, AS THESE ARE NOT ABSOLUTE CERTAINITIES AS THERE ARE MANY VARIBLES (See detailed explanation below), HENCE RING AMPAGE MAXIMUM VALUES ARE JUST AN APPROXIMATE GUIDE. Let me put this another way.

SOCKET WIRE MANUFACTURERS make SKT WIRE of different diameters, the AMPAGE specified, does include a big safety margin.
For example 2.5mm skt wire ampage is rated to 27A.
To make a comparison, a 30A fuse wire (Used on rewireable fuses), is approximately ½ the diameter of 2.5mm skt wire. Hence the real ampage load of 2.5mm skt wire is much greater then 27A, how big a safety margin skt wire manufacturers have worked into their stated ampages is anybodies guess, and I’m not going test skt wire until it melts to discover what is the absolute maximum of skt wire before it melts. But of course the stated AMPAGE is intended for CONTINOUS use (Or not) for a great many years, that is the life of buildings (Houses, businesses, factories, sky scrapers, etc), as buildings do NOT routinely need skt wire replacing, obviously!

Hence socket wire manufacturers do not specify RING AMPAGE per SKT WIRE diameter on their skt wire reels that I’ve ever bought, instead the approx specifying of RINGED skt wire is left to BRITISH STANDARDS. But IEE only stipulates the most commonly used skt wire, 1.5mm, 2.5mm & 4mm for RING circuit AMPAGE values (IEE 17th Edition, Pg44).

Obviously stated RING AMPAGE of skt wire can’t be less then stated AMPAGE of skt wire, and it is less then double. An incorrect assumption, is that ringing doubles ampage, it does not. For example, even if a RING circuit was an even loop, and the only LOAD was at the RING loop end, the flow of electrons (anions - and cations +) will NOT necessarily be drawn by the LOAD from SUPPLY in even amounts from each length of skt wire from the fusebox.
Hence RINGing is less then double: 1.5mm 20A x 1.6 = 32A (As stipulated by IEE 17th Edition), so this is 1.6 times the stated AMPAGE of the skt wire (32A/20A=1.6).
And since skt wire length depends on room size and next nearest skt/fixture, and watts used and the length of time a light/appliance is used for, varies widely, hence watts load drawn from each skt in a RING is likely to be different.
And to make my point more obvious in a RING circuit, if a skt wire is near to the fusebox, then the load will be drawn to nearest supply, hence the electrons will NOT flow evenly through both lengths of skt wire, INSTEAD the load draws electrons from the skt wire length nearest to the fusebox, hence since RINGING circuits AMPAGE maximum load depends on the nearest direction of supply for electrons to follow, hence quoted RING AMPAGE figures are/would be a very approximate guide. And since consumed watts will NOT necessarily be known hence IEE and other REFERENCE GUIDES also stipulate RING maximums in SQUARE METRE lengths, hence when consumed watts not known RINGED CIRCUITS maybe calculated solely using Square metre calculation, eg 4mm RING 100m2. Then electric contractors will plan circuits from calculating room/hall square metre dimensions, for ring circuits to be fitted, when watts maximum/average consumed unknown, etc.

IF YOU HAVE VIDEOS/ANIMATIONS/DIAGRAMS OF ELECTRONS FLOWING, ESPECIALLY IN RING CIRCUITS, I’D BE VERY INTERESTED IN SEEING THOSE.

TO REITTERATE, OBVIOUSLY IEE AND SKT WIRE MANUFACTURERS ARE VAGUE ABOUT SPECIFYING RING AMPAGE MAXIMUM VALUES, AS THESE ARE NOT ABSOLUTE CERTAINITIES AS THERE ARE MANY VARIBLES, HENCE RING AMPAGE MAXIMUM VALUES ARE JUST AN APPROXIMATE GUIDE.

So you nonsense talkers, give it a rest & stop deliberately "wasting my time", and anybody who can add reliable approx ring ampages to the following, speak up:
1mm RINGED approx ? (Not Ringed Ampage = 15A)
1.5mm RINGED approx 30A to 32A (Not Ringed Ampage = 20A)
2.5mm RINGED approx 30A to 32A (Not Ringed Ampage = 27A)
4.0mm RINGED approx ? (Not Ringed Ampage = 36A)
6.0mm RINGED approx ? (Not Ringed Ampage = 46A)
10.0mm RINGED approx ? (Not Ringed Ampage = 63A)
16.00mm RINGED approx ? (Not Ringed Ampage = 85A)

ELEC GAS WATER autocalc 1st tab, scroll down

FUSEBOX MCB autocalc 3rd & 4th tab

Cheers

Stephan


ELEC GAS WATER autocalc 1st tab, scroll down

FUSEBOX MCB autocalc 3rd & 4th tab

 

[malcolmsanford]

There you go as clear as day ...................and lets stop discussing things in a forum, as forums are not set up for discussions, as it is clearly wasting Mr Srands time, who thought it so insignificant that he wrote a tome on the subject, which explains everything so clearly.

So to fellow members please stop using the forum as a sounding board, or a discussion platform and instead use it as it was intended as a .........................

 

[Penance]

srands, it was mentioned that a cooker supply should be just that, a cooker/hob only with kitchen sockets on their own ring.
Why keep asking about other appliances on the cooker circuit?

 

[malcolmsanford]

srands, it was mentioned that a cooker supply should be just that, a cooker/hob only with kitchen sockets on their own ring.
Why keep asking about other appliances on the cooker circuit?

Now if I answer that I'm going to get into trouble, your trying to get me in trouble aren't you Penance

 

[Penance]

Now if I answer that I'm going to get into trouble, your trying to get me in trouble aren't you Penance

Oh go on, i'll take the blame

 

[telectrix]

i've just pressed my delete button, but she no work, thread is still there.

 

[srands]

As per the example given in the NICEIC TECHNICAL MANUAL, of a RING circuit, calculated using the KIRCHOFF equation.

Here is a SPREADSHEET with formulas for the example in the NICEIC TECHNICAL MANUAL.

EXAMPLE1:

SKT D to A: 32A(TOTAL OF A+B+C), 20m's
SKT A: 12A, AtoB 15m's
SKT B: 14A, BtoC 20m's
SKT C: 6A, CtoD 5m's

SIMPLY, "IF" this was a RADIAL CIRCUIT were the WATTS/AMPS MAXIMUM was known (32A), the SKT WITE to be used/spec'd would suggest 4mm SKT WIRE.

QUESTION: SIMPLY, what SKT WIRE would "you" use here for the RING MAIN example (Given the recognised KIRCHOFF equation)? 3 SKTS EXAMPLE1 ABOVE.
Please show your workings, I have shown mine long hand in the SPREADSHEET, which is the short hand version of the KIRCHOFF equation. If you have a better spreadsheet I'm sure this of interest to all electricians and DIYERS.

Obviously the KIRCHOFF equation doesn't actually reduce the actual WATTS/AMPS used, it calculates the AMPAGE spread over the RING MAIN, as an approximate. But isn't the KIRCHOFF equation the recognised standard equation for calculating a RING MAIN.

ALSO I realise in addition to KIRCHOFF, the IEE 17th Edition Pg44 qoutes something like:
1.5mm (20A not ringed) or 2.5mm (27A not ringed) is approx 32A Ringed, <less then 100m's (# 20A x 1.6 or 27A x 1.2).
Hence on the 3rd tab of the spreadsheet, I guess this is how they reached 32A, or a sliding scale of multiplication as you can see in the pattern #, or unless they destructively tested socket wire in collaboration with socket wire manufactuers such as Prysmian, and the suggested figures were thought reasonable for permanent use for a great many years, well socket wire isn't going to twist and bend behind plastered walls.

Cheers

Stephan

RING AMP CALC: Add your comments/workings and upload/post

FUSEBOX MCB autocalc 3rd & 4th tab


ELEC GAS WATER autocalc 1st tab, scroll down


LONG HAND OF EXAMPLE1 with KIRCHOFF short hand:

SKT D to A: 32A(TOTAL OF A+B+C), 20m's, Cumlative Count 0A
SKT A: 12A, AtoB 15m's, Cumlative Count 12A
SKT B: 14A, BtoC 20m's, Cumlative Count 26A
SKT C: 6A, CtoD 5m's, Cumlative Count 32A

i) Metres of Skt wire X Cumlative Count of AMPs from skts in circuit:
20 X 0 = 0
15 X 12 = 180
20 X 26 = 520
5 X 32 = 160
0+180+520+160=860

TOTAL i) / LENGTH TOTAL - Cumlative Count of Amps in circuit = AMPs of SKT LENGTH
D to A = 860 / (20+15+20+5) - 0 = 14.33A
A to B = 860 / (20+15+20+5) - 12 = 2.33
B to C = 860 / (20+15+20+5) - 26 = -11.67
C to D = 860 / (20+15+20+5) - 32 = -17.67

SEE NICEIC TECHNICAL MANUAL Pg 5

Given this example if RADIAL then 32A would use 4mm SKT WIRE. So if RING circuit what SKT WIRE would you use, given the above? Please show workings.

If the above are totalled together: 14.33A + 2.33A + -11.67A + -17.67A = 19.3A
Does the equate the AMPAGE spread over the SKT WIRE? Hence 1.5mm SKT WIRE?

Cheers

Stephan

RING AMP CALC: Add your comments/workings and upload/post

FUSEBOX MCB autocalc 3rd & 4th tab

ELEC GAS WATER autocalc 1st tab, scroll down​

 

[Lou7]

If you're using grid switches, why not use a grid fuseholder aswell, then you can run to appliance in 1.5 and use a flex outlet plate. No pulling out appliance if the fuse ever blows.

 

[Smugley]

Customer wanted minimal stuff on the wall and the grid fuses look a bit ugly. Also you don't achieve satisfactory discrimination with two inline 13A fuses.

 

[Lou7]

I know what you mean. But I try not to put socket outlets behind appliances, If the plug top fuse blows you've got to get the appliance out. Cut the plug top off and use flex outlet.