Cooker hood and bathroom fan connection via duel appliance outlet plate.

[Tonykakz]

I wish to install a bathroom extractot and cooker hood from an existing 32 amp 6mm cable . I intend to use a duel applliance outlet plate to split into two 6mm cables running to seperate 3amp FCU's from there 1mm cables to all parts that follow . See diagram . Is this in line withs regs. Thanks .

 

[Tonykakz]

I wish to install a bathroom extractot and cooker hood from an existing 32 amp 6mm cable . I intend to use a duel applliance outlet plate to split into two 6mm cables running to seperate 3amp FCU's from there 1mm cables to all parts that follow . See diagram . Is this in line withs regs. Thanks .

 

[sinewove]

View attachment 85532

From the duel plate ,you could run 2 2.5mm cables to the fused spurs since the 3A fuses protectect the 2.5 cables from overload.Or you could change the mcb in the consumer unit to 6A and use 1.5mm cable from the cooker plate.Rcd protection would be required for the bathroom fan and any buried cables.
Regards,
S

 

[Tonykakz]

From the duel plate ,you could run 2 2.5mm cables to the fused spurs since the 3A fuses protectect the 2.5 cables from overload.Or you could change the mcb in the consumer unit to 6A and use 1.5mm cable from the cooker plate.Rcd protection would be required for the bathroom fan and any buried cables.
Regards,
S

Is it ok to down grade the cable size from the duel outlet appliance to the FCU's. I always thought you could only down grade the cable size after the FCU's. The cable size to the outlet plate is 6mm and is on a 32 amp circuit. Thanks for your help. But just want to be 100% certain.

 

[sinewove]

Is it ok to down grade the cable size from the duel outlet appliance to the FCU's. I always thought you could only down grade the cable size after the FCU's. The cable size to the outlet plate is 6mm and is on a 32 amp circuit. Thanks for your help. But just want to be 100% certain.

Yes,because the fused spur prevents the 2.5mm cable carrying more than 3A,so no danger to the cable.Same as spuring a twin socket on a 2.5 from the 32A mcb on a ring final.The twin skt limits the current to 26A.
S

 

[Tonykakz]

Yes,because the fused spur prevents the 2.5mm cable carrying more than 3A,so no danger to the cable.Same as spuring a twin socket on a 2.5 from the 32A mcb on a ring final.The twin skt limits the current to 26A.
S

Thanks. Kind regards.

 

[Tonykakz]

Thanks. Kind regards.

But at the same time there would be no real problem if i keep.the design as is in my diagram . With 2x 6mm cables going to the FCU's. Would this still be exceptable as the 3amp FCU's would limit power to extractor fans.

 

[telectrix]

looks a tfirst glance a n awkward way to do it. i would separate the 2 circuits. run cooker hood from cooker outlet (fused down) and the bathroom fan independently from the lighting circuit.

 

[Tonykakz]

looks a tfirst glance a n awkward way to do it. i would separate the 2 circuits. run cooker hood from cooker outlet (fused down) and the bathroom fan independently from the lighting circuit.

Yes this is another option. Thanks.

 

[Dartlec]

But at the same time there would be no real problem if i keep.the design as is in my diagram . With 2x 6mm cables going to the FCU's. Would this still be exceptable as the 3amp FCU's would limit power to extractor fans.

There''s nothing that breaches any regulation in doing it that way - but you'll find it tricky to terminate 6mm in many FCUs and will need a deeper back box/pattress that you would otherwise.

In terms of how future users might expect it to be done, (that isn't a particular reg), then @telectrix method is one I would favour as well unless this was really more convenient in terms of access. (I presume the kitchen and bathroom are close together?).

If the existing Cooker feed is not RCD protected, then you would almost certainly have to add it for the new cables, unless they were all surface mounted - and it would be needed for the bathroom fan in any case.

If it was done this way I would also make a note at the consumer unit of the new additions to the circuit for future electricians/owners.

 

[Tonykakz]

There''s nothing that breaches any regulation in doing it that way - but you'll find it tricky to terminate 6mm in many FCUs and will need a deeper back box/pattress that you would otherwise.

In terms of how future users might expect it to be done, (that isn't a particular reg), then @telectrix method is one I would favour as well unless this was really more convenient in terms of access. (I presume the kitchen and bathroom are close together?).

If the existing Cooker feed is not RCD protected, then you would almost certainly have to add it for the new cables, unless they were all surface mounted - and it would be needed for the bathroom fan in any case.

If it was done this way I would also make a note at the consumer unit of the new additions to the circuit for future electricians/owners.

Thank you. Yes bathroom and kitchen and consumer unit are all close to each other . Only short cables required. Already have two FCU's from cooker control unit via duel plate for cooker and hob, so i think cannot add 3 appliance. So maybe i will stick with my design and down size the two cables to 2x 2..5 T&E from duel plate to FCU's. That is ok right ? As Sinewove stated.

 

[Dartlec]

Thank you. Yes bathroom and kitchen and consumer unit are all close to each other . Only short cables required. Already have two FCU's from cooker control unit via duel plate for cooker and hob, so i think cannot add 3 appliance. So maybe i will stick with my design and down size the two cables to 2x 2..5 T&E from duel plate to FCU's. That is ok right ? As Sinewove stated.

Yes, it is acceptable - as long as it's a fixed load at each end (the FCU) then 2.5mm is fine as even if a 13A fuse was added to the FCU it could not overload the cable.

Is the feed you're planning to use RCD protected?

I should point out that if the extractor fan in the bathroom is new (and arguably even if it isn't since its a new cable to it), then it may well be notifiable to building control under Part P of the building regulations. (If it is within the zones). The easiest way to do that is to get a registered electrician to do it, though there are other ways.

 

[Tonykakz]

Thank you. Yes bathroom and kitchen and consumer unit are all close to each other . Only short cables required. Already have two FCU's from cooker control unit via duel plate for cooker and hob, so i think cannot add 3 appliance. So maybe i will stick with my design and down size the two cables to 2x 2..5 T&E from duel plate to FCU's. That is ok right ? As Sinewove stated.

Yes, it is acceptable - as long as it's a fixed load at each end (the FCU) then 2.5mm is fine as even if a 13A fuse was added to the FCU it could not overload the cable.

Is the feed you're planning to use RCD protected?

I should point out that if the extractor fan in the bathroom is new (and arguably even if it isn't since its a new cable to it), then it may well be notifiable to building control under Part P of the building regulations. (If it is within the zones). The easiest way to do that is to get a registered electrician to do it, though there are other ways.

Thats great. Yes all RCD protected . So this offers a safty net. Thanks for all the advice to all who replied.

 

[polaroid]

FYI with regards to placing FCU beyond the point of cable reduction:

434.2.1 Except where Regulation 434.2.2 or 434.3 applies, a device for protection against fault current may
be installed other than as specified in Regulation 434.2, under the following conditions:
In the part of the conductor between the point of reduction of cross-sectional area or other change and the position
of the protective device there shall be no branch circuits or socket-outlets and that part of the conductor shall:
(i) not exceed 3 m in length, and
(ii) be installed in such a manner as to reduce the risk of fault to a minimum, and
NOTE: This condition may be obtained, for example, by reinforcing the protection of the wiring against external
influences.
(iii) be installed in such a manner as to reduce to a minimum the risk of fire or danger to persons.

Length and.... protection from damage need to be considered as damage to the cable after the CSA reduction but before the fuse, the fault current will over load the cable before the main protective device trips?

Open to correction

 

[Dartlec]

FYI with regards to placing FCU beyond the point of cable reduction:

434.2.1 Except where Regulation 434.2.2 or 434.3 applies, a device for protection against fault current may
be installed other than as specified in Regulation 434.2, under the following conditions:
In the part of the conductor between the point of reduction of cross-sectional area or other change and the position
of the protective device there shall be no branch circuits or socket-outlets and that part of the conductor shall:
(i) not exceed 3 m in length, and
(ii) be installed in such a manner as to reduce the risk of fault to a minimum, and
NOTE: This condition may be obtained, for example, by reinforcing the protection of the wiring against external
influences.
(iii) be installed in such a manner as to reduce to a minimum the risk of fire or danger to persons.

Length and.... protection from damage need to be considered as damage to the cable after the CSA reduction but before the fuse, the fault current will over load the cable before the main protective device trips?

Open to correction

That's correct for any given situation I'd agree

in this case, we have a 32A OPCD and 2.5mm feeds to the FCUs, which is equivalent to a spur on a Ring Final Circuit, which as we know is acceptable (with no 3m limit that I'm aware of either...)

In any other combination of cables/OPCD, you could use the adiabatic and other calculations to determine whether the cable could deal with fault protection along it's length...

In this case, with a quick calc and some assumptions, the cpc requirement is less than 1.5mm for most cases.

The fact that an RCD is installed also should ensure rapid disconnection for any cable damage.

Provided the cables are run in safe zones, with suitable installation practices, I don't think there is anything 'wrong' with this setup, though it is not necessarily the one I would choose.

There is the caveat about Part P notification for the bathroom fan, and that correct installation does require testing that the earth is correctly terminated at each point of the chain.

 

[Tonykakz]

FYI with regards to placing FCU beyond the point of cable reduction:

434.2.1 Except where Regulation 434.2.2 or 434.3 applies, a device for protection against fault current may
be installed other than as specified in Regulation 434.2, under the following conditions:
In the part of the conductor between the point of reduction of cross-sectional area or other change and the position
of the protective device there shall be no branch circuits or socket-outlets and that part of the conductor shall:
(i) not exceed 3 m in length, and
(ii) be installed in such a manner as to reduce the risk of fault to a minimum, and
NOTE: This condition may be obtained, for example, by reinforcing the protection of the wiring against external
influences.
(iii) be installed in such a manner as to reduce to a minimum the risk of fire or danger to persons.

Length and.... protection from damage need to be considered as damage to the cable after the CSA reduction but before the fuse, the fault current will over load the cable before the main protective device trips?

Open to correction

I thank you for your advice. I will take this into account. I think i will not reduce the cable size to the FCU's just to be on the safe side. Yes that was my concern about reducing the cable size before the FCU's, yes the real danger of overloading the reduced cable size before the fuse blows. Thanks.

 

[polaroid]

I thank you for your advice. I will take this into account. I think i will not reduce the cable size to the FCU's just to be on the safe side. Yes that was my concern about reducing the cable size before the FCU's, yes the real danger of overloading the reduced cable size before the fuse blows. Thanks.

I just thought I would state the regulation for information purposes but Dartlec does make some very good points in relation to my post so please consider those.

With RCD protection and if the cables routes are chosen carefully i don't think it would be much of an issue.

 

[Tonykakz]

That's correct for any given situation I'd agree

in this case, we have a 32A OPCD and 2.5mm feeds to the FCUs, which is equivalent to a spur on a Ring Final Circuit, which as we know is acceptable (with no 3m limit that I'm aware of either...)

In any other combination of cables/OPCD, you could use the adiabatic and other calculations to determine whether the cable could deal with fault protection along it's length...

In this case, with a quick calc and some assumptions, the cpc requirement is less than 1.5mm for most cases.

The fact that an RCD is installed also should ensure rapid disconnection for any cable damage.

Provided the cables are run in safe zones, with suitable installation practices, I don't think there is anything 'wrong' with this setup, though it is not necessarily the one I would choose.

There is the caveat about Part P notification for the bathroom fan, and that correct installation does require testing that the earth is correctly terminated at each point of the chain.

I just thought I would state the regulation for information purposes but Dartlec does make some very good points in relation to my post so please consider those.

With RCD protection and if the cables routes are chosen carefully i don't think it would be much of an issue.

So let me recap! From consumer unit 32amp circuit RCD protected . 6mm Cable of around 7 to 8 feet long runs to airring cupboard. Here is where the new work begiins . This was.an old shower cable . So i want to split the cable two way using a duel.plate . From the duel plate run two 6mm or 2.5 mm cables to 2 FCU's cables to FCU's no more than 4 inches long. Then for the Bathroom fan a cable of 4 inches into fan isolator. Then a cable of 14 inches into junction box and then a cable of 6 feet to bathroom extractor . All cable size from FCU will be 1mm. For the cooker hood from the FCU run a cable of 3 feet to flex outlet plate and connect to cooker hood. So the only real issue hereis if it is permitted to reduce the cable size of 6mm from consumer unit running to Duel plate to 2.5 from duel plate to FCU's of stick with the 6mm run right through to FCU's.

 

[polaroid]

If it's just 4 inches don't worry about what I mentioned... You'll be fine.

 

[Tonykakz]

If it's just 4 inches don't worry about what I mentioned... You'll be fine.

So its 100% ok to go with 6mm or 2.5 before FCU's?