Fixed Ring in Kitchen - Wanted to check my understanding

[Dave78]

Hi all, I've just been talking with a kitchen fitting company as we're currently looking at (surprise surprise) getting a new kitchen. Anyway, we are wanting to add in a dishwasher, and also replacing the existing freestanding fridge/freezer with two separate under counter ones.

I've tried to draw out what is being suggested, given a picture is worth 1000 words and all that. Black is existing, red is what's new. All the wiring is 2.5mm T+E

As I understand what they are proposing, is to replace the existing back box of two of the existing FCU with a dual back box. Take one of the ring wires into one of the FCU, and the other wire into the other FCU, and then connecting the two together. Thereby effectively adding in an extra FCU to the fixed ring. There was talk about using a MK Grid plus with two switches and two fuses so it'd all fit in a standard 2gang back box - but the idea is the same.

I understand the adding of the FCU's to the circuit - the logically and physical actions of connecting it all up all make sense. However my concerns are mostly around the loadings all that could put on the circuit. I know we're mostly likely going to have both washing machine and dishwasher on together overnight (according to their spec's they can both pull in 10A) so that's a possible 20A before anything else. I've been trying to find out this afternoon some info on the others.

I'd rather be able to say now to the kitchen company, nope we have to have an additional circuit, and that all get costing in - than have the kitchen finished and then start having it trip when things are on. And then start having to change circuits etc.

So could I:
a) check that is this an ok modification to the circuit for them to be suggesting?
b) should I be concerned about the loadings of this circuit.

Thanks all.

 

[Wilko]

Hi Dave and Welcome to the Forum !
If you want an extra circuit now is definitely the time, it might just cost a bit more. FYI my family kitchen has a similar 32A rfc set up, only with an extra microwave, dryer, toaster, kettle and fridge. I would prefer to have a second circuit myself, but the existing circuit works fine with no problems.
Can I ask what circuit have you got for the oven?

 

[Pete999]

Where do all the 13Amp switched sockets for Kitchen use, and Oven supplies fit into your scheme, as all I see are switched fused spurs and and non switched spurs.

 

[westward10]

Where do all the 13Amp switched sockets for Kitchen use, and Oven supplies fit into your scheme, as all I see are switched fused spurs and and non switched spurs.

I think he is just showing the part to be altered, seems fine to me.

 

[Midwest]

I would be very surprised to see any domestic appliance (non cooking) drawing 10A's, it would ruin those pretty economy data sheets they have to provide.

Who is this kitchen installer?

 

[Pete999]

I think he is just showing the part to be altered, seems fine to me.

Right

 

[Octopus]

The loading you suggest is unlikely to trip a MCB.

how old is your fuse board?

 

[Dave78]

Where do all the 13Amp switched sockets for Kitchen use, and Oven supplies fit into your scheme, as all I see are switched fused spurs and and non switched spurs.

Hi Pete, Yes sorry only showed the fixed ring that was to be changed. the 13Amp switched sockets are on a different circuit and the oven is on it's own circuit altogether.

 

[Dave78]

The loading you suggest is unlikely to trip a MCB.

how old is your fuse board?

I expect about 20 years old, as guessing (I know should never guess anything) it's the one put in when the house was built about 20 years ago.

I had been wondering about when the electrical work is done in the kitchen, getting the whole house checked for any other electrical work so it can have a complete clean bill of health.

 

[telectrix]

you don't need FCUs for each under worktop appliance. a 20A D/P switch is a better option, as each appliance has a 13A fuse in it's plug top.

 

[westward10]

you don't need FCUs for each under worktop appliance. a 20A D/P switch is a better option, as each appliance has a 13A fuse in it's plug top.

Such switches are not tested for the current carrying capacity of a ring final circuit like BS1363 fuse connection units. How would they be a better option.

 

[telectrix]

Such switches are not tested for the current carrying capacity of a ring final circuit like BS1363 fuse connection units. How would they be a better option.

the 20A switches will only need to handle the current drawn by 1 appliance, which is fused @ 13A.

 

[Des 56]

This is another old argument where the two sides never the twain shall meet

The 20 amp switch would be a better option if only because it omits one unnecessary fuse from the equation
The doubts always expressed about them have ccc unsuitable for a ring are a red herring in my estimation
The switch contacts may be 20 amp but the actual feed connections are no different to those of a socket,the same brand items are often identical in size/ shape

 

[westward10]

the 20A switches will only need to handle the current drawn by 1 appliance, which is fused @ 13A.

It is nothing to do with the switching current but the incoming terminals on the switch which are not tested for ring final circuit requirements.

 

[telectrix]

i'm with des. can't see a problem. what if the ring conductors went into a 3 port wago with 1 conductor to the switch terminal?

 

[shaun1]

As a side note (and nothing to do with the electrical requirements) I recently moved from a kitchen with a fridge freezer to one with an under counter built in fridge, and found it a massive step backwards. There is a lot less space and it's very hard to find things without getting down on hands and knees.

 

[Dave78]

With regards the whole not needing a FCU and just having a 20A DP switch above the worktop. I understand why there's no need to have a fuse as there's one in the plug. I've also been told you can always unplug it if you wanted to switch it off/isolate it. But would much rather have a switch to switch it off if going away for a while.

Personally (and this is just a personal viewpoint) I would rather have a switch and fuse where I can easily access them, and then have the actual appliance hard wired into the circuit (so not just plugged in with the 13A plug under the worktop). So should a fuse need replacing I don't then have to take the built in appliance out just to replace a fuse.

I know one of my friends who has some appliances plugged into hard to reach places, just down rates the fuse on the FCU - for example the fridge is plugged in under the worktop with it's as delievered 13A plug, but there's a 10A fuse in the FCU - logic being that the 10A should let go well before the 13A in the plug and therefore much easier to get to in order to replace.

 

[Dave78]

As a side note (and nothing to do with the electrical requirements) I recently moved from a kitchen with a fridge freezer to one with an under counter built in fridge, and found it a massive step backwards. There is a lot less space and it's very hard to find things without getting down on hands and knees.

We've looked and the under counter fridge is about the same size as our current fridge in the fridge/freezer. I'll let the wife know about the having to find things aspect as it's not something I've thought of. Our main reason for moving to under counter is we can then squeeze in a corner unit (on both floor and wall) giving us lots more storage space, which we can then move things off the worktop and giving us more worktop space in the process, in addition to the corner unit giving us more worktop space.

 

[telectrix]

We've looked and the under counter fridge is about the same size as our current fridge in the fridge/freezer. I'll let the wife know about the having to find things aspect as it's not something I've thought of. Our main reason for moving to under counter is we can then squeeze in a corner unit (on both floor and wall) giving us lots more storage space, which we can then move things off the worktop and giving us more worktop space in the process, in addition to the corner unit giving us more worktop space.

on that basis then, i'd use the under counter fridge and freezer for things like milk, eggs, beer, etc; stuff you want to hand regularly, and retain the fridge freezer in utility room, garage , or similar easily accessible location for main storage.

 

[westward10]

Have I wandered on to another Forum.

 

[Dave78]

Sorry westward10, back on topic now

In terms of under counter sockets/connections with built in appliances. What is the general viewpoint between just plugging the appliance into an unswitched socket, and cutting the plug off (assuming it has one) and wiring it into a flex outlet on the wall?

Obviously the second method need a FCU.

 

[Midwest]

Personally, if possible I would always plug an appliance into a socket outlet, rather than cutting off plug & wired into flex outlet. This allows the appliance to be easily removed for maintenance & cleaning, by the householder (for example).

However, due to some kitchen designs and lengths of appliance leads, this is not possible. So cutting off the plug top, and using a flex outlet is perhaps the only option.

PS I did ask who the kitchen installer was? If it's the likes of Wren or BQ, get your own electrician, don't use theirs. If it's a local company, use their electricians.

 

[telectrix]

Have I wandered on to another Forum.

yup.this is Alice in Blunderland.

 

[Des 56]

I know one of my friends who has some appliances plugged into hard to reach places, just down rates the fuse on the FCU - for example the fridge is plugged in under the worktop with it's as delievered 13A plug, but there's a 10A fuse in the FCU - logic being that the 10A should let go well before the 13A in the plug and therefore much easier to get to in order to replace.

[QUOTE="Dave78, post: 1




Regards a 10 amp fuse in your fcu or plug top
3 and 13 amps are the accepted standards

I believe the Iet and/or the manufacturers had a look at fuses a while back,their conclusion was the time it took to pop fuses in the 1 to 13 amp range was very similar and differences in the times are essentially much the same for all of them
The differences was only enough to justify a 3 amp and 13 amp as being worthwhile ratings as far as any useful difference was concerned

 

[davesparks]

Such switches are not tested for the current carrying capacity of a ring final circuit like BS1363 fuse connection units. How would they be a better option.

The terminals of a 20A switch must logically be suitable for 20A, and 20A is the required ccc of the cable used for the ring circuit. This suggests that perhaps the terminals are good for the current does it not?

 

[stevethesparks]

Just to add, looking at an MK fcu and a MK dp switch, the terminals are identical.

 

[westward10]

The terminals of a 20A switch must logically be suitable for 20A, and 20A is the required ccc of the cable used for the ring circuit. This suggests that perhaps the terminals are good for the current does it not?

I don't disagree but ring final circuits are often unbalanced and whilst this maybe negligible and variable it is not impossible for parts of the circuit to have currents in excess of 20A flowing.

 

[westward10]

Just to add, looking at an MK fcu and a MK dp switch, the terminals are identical.

They may well look the same and probably are. I believe BS1363 tests do not subject the terminals to 30/32A but 20A for a constant period of four hours, whether this is a terminal test or a test which includes all components I am not sure. Whether EN60669-1 switches are subjected to the same tests I do not know. Maybe consulting manufacturers and obtaining written guarantees as to whether they are suitable for direct connection to ring final circuits is a step which should be taken.

 

[davesparks]

I don't disagree but ring final circuits are often unbalanced and whilst this maybe negligible and variable it is not impossible for parts of the circuit to have currents in excess of 20A flowing.

I should add that as an apprentice I was taught that it's wrong, and I never have fitted a 20A switch on a ring. But the logic is there and I don't think I'd comment on it if I came across it in an installation.
Especially considering the average load on a whole domestic installation rarely more than around 20-30A

 

[valleybilly]

Hi Dave with the greatest respect , If u put fcu's above counter tops it will make the look of your kitchen accessory cluttered for want of a better word & will look naff . Dont do it . The chances of fuses going minimal / Going away so switchin them off Why ? / With respect your over thinking the worst case senario . What if the RCD trip when your away ? Do you have Tropical fish ? hint hint . If you have washer /dishwasher on over night stagger the start times man ! . In reality having an evenly distrabuted load on a ring main is not that realistic in any situation .

 

[valleybilly]

Hi Dave with the greatest respect , If u put fcu's above counter tops it will make the look of your kitchen accessory cluttered for want of a better word & will look totaly naff . Dont do it . The chances of fuses going minimal / Going away so switchin them off Why ? / With respect your over thinking the worst case senario . What if the RCD trip when your away ? Do you have Tropical fish ? hint hint . If you have washer /dishwasher on over night stagger the start times man ! . In reality having an evenly distrabuted load on a ring main is not that realistic in any situation .

 

[davesparks]

Hi Dave with the greatest respect , If u put fcu's above counter tops it will make the look of your kitchen accessory cluttered for want of a better word & will look totaly naff . Dont do it .

It's a functional room, not a work of art!

 

[valleybilly]

work of art
noun
noun: work of art; plural noun: works of art

1. a painting, sculpture, poem, piece of music, or other product , especially one with imaginative or aesthetic appeal.
   • something that is very attractively presented or detailed.
     "even the salad is a work of art" lol

 

[Risteard]

logic being that the 10A should let go well before the 13A in the plug

Unfortunately that "logic" is entirely without merit, though.

 

[charlie76]

the 20A switches will only need to handle the current drawn by 1 appliance, which is fused @ 13A.

What about a fault on the cable between the switch and the plug

 

[Colin33]

I agree with the argument that extra switches above worktop are just un-necessary clutter! Especially for fridges/freezers, what it they're turned off accidentally? Surely a socket located in an adjacent kitchen cabinet is the way, and can simply be spured from a socket on the ring above the worktop. No need for 20A switches or extra fuses and sleepless nights worrying about whether those 20A connections are getting warm....

 

[Midwest]

I do a fair few kitchens, and give my customers the options of DP's above work tops or just sockets in adjacent cupboards, only had one recently who went for DP's.

And when customers are paying thousands for glossy kitchen units, granite or composite work tops, wine bars, freezer draws (you get the picture), they are (to them) works of art. Not to be spoiled by faceplates. I think some of them would do without socket outlets, if it weren't for the need to plug in their juicers or baristas machines.

I got DP switches

 

[Toneyz]

As I have posted before on this subject nearly all the mainstream new house builders have in their specs bank of D.P. grid switches I kept on pointing out to them that these should be located as near as practicably possible to the centre of the kitchen RFC.A lot of it is down to personal taste of the customer As for the ratting of the supply terminals of the D.P. switches this is something only the manufactures & BSI can put to bed.

 

[Paul Taylor]

Use switch grids, and have them dp 20 amp switches, get them engraved. If you can pull out your fridge and freezer I would just have an unswitched socket behind it.

 

[Deleted member 26818]

BS1363 type testing, tests the terminations at 20A.
Single sockets are tested with 14A via the plug and 6A via the terminals at the rear with a total load of 20A on the feed to the socket.
Double sockets are tested with 14A at one socket and 6A on the other.