Containment for island electrical points

[padstar]

I have just re read my post from earlier and think i may have caused some confusion as to what is in the island.

The single ring main currently suggested by the elctrician for the Kitchen/Utility/Island is split (Location wise) as below;

Fridge (Kitchen)
Freezer (Kitchen)
Extractor (Kitchen)
2 double sockets (Kitchen)

Washing Machine (Utility Room)
Tumble Drier (Utility Room)
2 double sockets (Utility Room)

Dishwasher (Island)
Wine fridge (Island)
Quooker hot tap (Island)
Food disposal unit (Island)


Ovens and Hob are on separate radials


Is the above any more than most kitchens that are run on a single ring main? Hot tap rather than kettle, maybe a washer and drier rather than a single W/D and an extra fridge?

 

[EFLImpudence]

Is this work just using and modifying the existing cables to the kitchen and utility room?
That is, there is only one Ring Final Circuit to the two rooms at present.

If so, then without more extensive work you have little choice than to have all the items on the one ring.
It is nothing out of the ordinary.

 

[plugwash]

Real world experience says a 32A circuit is fine for domestic kitchens as long as you keep ovens/cookers on their own circuits (and often even if you don't). Yes if everything was drawing full power at the same time you would have an overload but breakers don't trip the instant there is a small overload and most high-power domestic appliances only draw full power for a short time.

 

[padstar]

Its a new install in a refurbishment/extension.

Ovens and hobs are on separate supplies.

The chances of everything being used at the same time are fairly low.

 

[SUNRAY]

Getting back to CONTAINMENT in your title.

Yes I always advocate cable management to make any later alterations possible without ripping up the floor. If it's a concrete floor I'd be installing conduit/duct capable of carrying at least double anything you plan for, i'd be aiming for 35 or 50mm from at least 2 accessible locations.

 

[winston1]

Worth considering two 20 Amp 4mm radials to the island.

Why is it worth considering oversized cables? 2.5mm2 cables are more than adequate for 20amp radials. In fact 1.5mm2 could be used.

 

[bernardgreen]

Why is it worth considering oversized cables? 2.5mm2 cables are more than adequate for 20amp radials

Which to believe

(1) Calculations that show that 4mm² cable is required

(2) An opinion posted by a person with a history of posting misleading opinions

Voltage Drop Calculator

www.tlc-direct.co.uk

 

[JohnW2]

Which to believe .... (1) Calculations that show that 4mm² cable is required

The calculation you present shows that 4mm² cable would be required if the cable were installed using 'Method A' (enclosed in conduit in a thermally insulating wall).

Why did you choose that installation method for your calculation?

Kind Regards, John

 

[FrodoOne]

padstar wrote
"The island will have a fridge (left hand unit), dishwasher (right hand unit) and hot tap and waste disposal unit (center unit)."

Which means that the Freezer, Washing Machine, Tumble Drier, Wine fridge, Extractor and 4 double sockets will be elsewhere - or, will there be at least 1 "accessible" double socket-outlet on the "Island" ?
(Presumably, half of one double socket-outlet will be "dedicated" to a microwave oven - somewhere.)

There is no mention of a "Cooker" but there is an "Extractor", so the "Cook Top" is (presumably) Gas.
However, is the Oven also Gas or is there a seperate circuit for that?

padstar also wrote :-
"is it best to have 2 double sockets mounted within the center cupboard feeding all appliances or a double in the center and then a single under/behind the units to each side?"
The socket-outlets should be mounted where they can be reached without moving the appliance being supplied.

Coming from a 240 V country where ONLY Radial circuits are allowed, putting all of that on one 32 A "Ring" circuit appears to be "lunacy" - One fault and they are all out - including the freezer.

With a "new" kitchen I would have at least two 20 A Radial circuits supplying several outlets, arranged with consideration to "diversity".

However, using 20 A radial circuits throughout the entire house usually allows for having no more than four (often three) such circuits, in even the largest houses (plus one or two radial lighting circuits.)
Hence, the maximum would be 6 Circuits, using RCBOs (or MCBs) (plus MCBs for "dedicated" circuits for any Air Conditioners and Ovens - (although RCBOs are now required for these in Australia.)

Bedrooms use little current (except for heaters) and laundry appliances are unlikely to be used when bedroom heaters are operating.
Lounge Rooms, TV Rooms, Dining Rooms etc. are generally not used at the same time as Bedrooms or Laundries (although there may be some overlap with Kitchen usage,
The feed to any attached garage/workshop can be shared with the Bedrooms or Lounge, again due to "diversity" reasons.

(I know that those in North America have problems with their "half hearted" Voltage but they now require 2 separate 20A feeds to socket-outlets in Kitchens plus separate 15A feeds to each of Refrigerators, Dishwashers, Waste Disposal Units, Microwave Ovens - and Laundry appliances., with the Dryers often being supplied with 240 V.)

 

[SUNRAY]

The calculation you present shows that 4mm² cable would be required if the cable were installed using 'Method A' (enclosed in conduit in a thermally insulating wall).

Why did you choose that installation method for your calculation?

Kind Regards, John

I'm guessing the concrete floor is insulated.

 

[SUNRAY]

Worth considering two 20 Amp 4mm radials to the island.

I was a little surprised at the post as my initial reaction was 2.5mm² should be plenty. In fact I penned this:

However, knowing Bernards usual accuracy, rather than make a silly fool of myself I used my head did this check:

So indeed our hallowed regulations indicate 2.5mm² is not large enough, in fact in the situation 2.5mm² is demonstrated to be too small for the ring circuit too.

Was I surprised to see:

Why is it worth considering oversized cables? 2.5mm2 cables are more than adequate for 20amp radials. In fact 1.5mm2 could be used.

some one suggesting not only using undersized cable but actually suggesting going even smaller?
We have an advice forum to provide accurate and SAFE advice

 

[bernardgreen]

Why did you choose that installation method for your calculation?

Because it is closest to the cable being installed in a duct under the kitchen floor

""insulated stud wall cable NOT touching plaster board"" would require 6mm²

We have an advice forum to provide accurate and SAFE advice

Given the number of posts from Winston1 that were somewhere between "unhelpful comment" and "in-accurate advice" it would improve the forum if his postings were vetted before appearing in public. Especially when a dangerous situation could be created if his "in-accurate advice" was taken to be accurate and was used by a DIYer in a project.

 

[padstar]

Thanks for the advice on the containment etc.

I had a chat with the electrician and he acknowledges some of the concerns raised regarding loads (mainly the hot tap). He sticks by the original plan of 1 ring main for kitchen/utility/island, but is happy to put the island on a 2nd ring main if i wanted to go "belt and braces".

As the floors are up and it is a new electrical installation, i assume this is advisable for the minimal extra cost of some wire and breaker?

 

[EFLImpudence]

According to those calculations, it would mean that 4mm² would also be required for a 32A ring circuit so a ring circuit is pointless.

A 4mm² radial could have a 25A MCB (if available for CU make) so one would probably suffice.
2.5mm² 16A radials would also be acceptable.


So Bernard was right saying two radials with 4mm² and 20A (or 25A) might be better - that is if 40A (or 50A) is required for an island.

All this, of course, assuming method C is not possible.

 

[JohnW2]

I'm guessing the concrete floor is insulated.

Although you may well be right, I think you're also guessing that it is a concrete floor in the first place. See also the reply I'm abot to write to bernard (to whom my question was directed.

Kind Regards, John