D
dayrider3883
I have installed a fan from the lighting switch to bathroom do i need to use a spur for the fan or can i go direct
Usually show the live feed is fused.
I always chuckle to myself when the old window in the bathroom is mentioned.
I always think to myself what happens when you go to look at that faulty fan mid December at half 3 and its almost dark outside, not much light in the bathroom then but you can isolate the fan if there isn't an isolator
I always chuckle to myself when the old window in the bathroom is mentioned.
I always think to myself what happens when you go to look at that faulty fan mid December at half 3 and its almost dark outside, not much light in the bathroom then but you can isolate the fan if there isn't an isolator
both. this means fusing down before the light.
O
Octopus
If the property hasn't got RCD protection, take the loop (before the light) into a FCU RCD, then out to the light, fan, etc. This way you can fuse down and have it all RCD protected. Nice and easy.
I think the regs should make an isolation switch for the fan mandatory!
I think the regs should make an isolation switch for the fan mandatory!
D
Deleted member 26818
Wouldn't comply with BS7671, as the whole circuit requires RCD protection, not just the part that enters the Bathroom.
O
Octopus
Really. Live and learn, so in the case of a spur from a ring why can we get away with a RCD FCU then sockets. At least I've been adding RCD protection and isolation switching - unlike MANY I see around here!
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D
Deleted member 26818
Yes it's a common misconception, although I believe that it's deliberate attempt to circumvent the Regulations, as using an RCD FCU is often a lot easier than providing RCD protection for the whole circuit.
701.411.3.3 Requires: "Aditional protection shall be provided for all circuits of the location, by the use of one or more RCDs having the characteristics specified in Regulation 415.1.1."
Which translated means all circuits supplying a location containing a bath or shower shall have 30mA RCD protection.
They've re-worded the Regulation in the amendment to only refer to LV circuits. We were hoping that this re-wording would have allowed the use of SELV equipment without the supply circuit having to be RCD protected, if the source of SELV was outside of the location. Unfortunately such is not the case. RCD protection is still required for the LV part of a SELV circuit, even though it will be as much use as a chocolate tea pot.
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timo1
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Good point, I thought you just had to make additions on older installations comply such as RCD sockets etc..and you were not obliged to upgrade the whole circuit?
O
Octopus
Back to my point, which is by using a FCU RCD and using this to supply the lights, fan and sometimes a shaver point the RCD is protecting all the circuits of the location i.e. in the said bathroom. PLUS there is a single point of isolation too.
There are too many homes around that don't have RCD's so IMHO my solution is certainly in the spirit of the regulation.
Got my Elecsa annual coming up so I might well ask him for his interpretation!
There are too many homes around that don't have RCD's so IMHO my solution is certainly in the spirit of the regulation.
Got my Elecsa annual coming up so I might well ask him for his interpretation!
D
Deleted member 26818
You must ensure that the addition or alteration complies with BS7671.
BS7671 only requires circuits of special locations to be RCD protected.
On other circuits, RCD requirements only apply to the socket-outlets and cables concealled in walls.
As such you can extend such circuits by for instance surface mounting any new cables, and using RCD socket-outlets. Leaving the existing part of the circuit without RCD protection.
However with circuits of special locations, the requirement is to provide protection for the circuit, by only protecting the extended part of such a circuit, you will not have met the requirements of BS7671.
D
Deleted member 26818
You don't, you take one live to the fuse, and two lives from the fuse.
O
Octopus
Or fit the FCU before it gets to the light and then everything after it is fused down!
D
Deleted member 26818
Wherever RCDs are placed in a position other than at the origin of a circuit, there is danger that an earth fault between the origin of the circuit and the RCD will bypass the RCD.
Whilst such a situation may not be considered a particular danger in normall circuits, where special locations are concerned, it is considered a particular danger.
As such BS7671 requires circuit protection for special locations, rather than RCD protection just for cables or equipment.
J
JUD
My interpretation is that if you supply the bathroom lighting from an RCD FCU attached to the original lighting circuit then this creates a new circuit starting at the FCU as that is now the protective device for that circuit.
As it also incorporates an RCD then IMO it complies with all relevant regs.
D
Deleted member 26818
Appendix 15 whilst only being informative, indicates that circuits start and in the case of RFCs finish at DBs.
It also indicates the FCUs are items of equipment supplied by final circuits, or devices used to provide overcurrent protection where the current carrying-capacity of a conductor is reduced.
There is no Regulation in BS7671 that suggests the origin of a circuit would be at an FCU.
J
JUD
The origin of a circuit is at an overcurrent protective device. In this case that overcurrent protective device is the FCU.
Haven't you ever wondered why the regs give max Zs values for 3 and 13A BS 1362 fuses.
You are mistaking the origin of a circuit with the origin of an installation.
Haven't you ever wondered why the regs give max Zs values for 3 and 13A BS 1362 fuses.
You are mistaking the origin of a circuit with the origin of an installation.
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D
Deleted member 26818
According to BS7671, the origin of a circuit is not neccessarily at the overcurrent device.
Regulations 433.2.2 434.2.1 indicate that devices can be installed along the run of a conductor, within 3m.
Whilst the definition of a circuit in Part 2: "Circuit. An assembly of electrical equipment supplied from the same origin and protected against overcurrent by the same protective device(s)."
Indicates that a circuit is protected by the same protective device, it does not indicate that the protective device is the origin of the circuit.
However the definition aside, the fact remains that Appendix 15 informs us that the origin of a circuit is at a DB, not at an FCU.
J
JUD
Nor does it state that the protective device has to be at a DB. Appendix 15 is not a regulation but more of an example of typical socket-outlet circuits.
In the case of the bathroom in the OP the assembly of electrical equipment is the light and the fan which will be supplied from the same origin (the FCU) and be protected against overcurrent by the same protective device (again the FCU)
This is why Zs info is provided for BS 1362 fuses. Because the light and fan in the bathroom are supplied by the 3A FCU their max Zs becomes 16.4Ω instead of say 7.67Ω as with a Type B BS 60898 breaker.
E
ezzzekiel
another usual argument, or just the addition you are responsible for
M
marks1
i have to agree with jud on this one. If you have an RCD FCU supplying the lights and the fan in the special location then you are complying with the regs. You don't have to protect the lighting circuit that isn't in the special location eg in the bedroom. However If there is a shower circuit in the special location that isn't rcd protected then this would also need upgrading to current regs even if you are not working on that circuit. That is what i interperate as "all circuits of the location"
D
Deleted member 26818
I am well aware that the definition of a circuit does not state that the protective device has to be at a DB.
I quoted the Definition to point out that a OPD is not considered to be the origin of a circuit.
Appendix 15 is not an example of typical socket-outlet circuits.
It sets out options for the design of ring and radial final circuits for houshold and similar premises in accordance with Regulation 433.1, using socket-outlets and fused connection units.
I accept that an FCU meets the requirements of an OPD as far as the definition of a circuit is concerned.
However the particular circuits we are discussing, are final circuits, and the requirements for final circuits are not just restricted to the definition of a circuit in Part 2 and those of Regulation 433.1.
Regulation 314.4 states: Where an installation comprises more than one final circuit, each final circuit shall be connected to a separate way in a distribution board. The wiring of each final circuit shall be electrically separate from that of every other final circuit, so as to prevent the indirect energizing of a final circuit intended to be isolated."
Now unles you are suggesting that the FCU, the light, the fan and associated wiring are not a final circuit, or that an FCU is a distribution board; how can having the origin of a circuit being an FCU meet the requirements of Regulation 314.4?
I quoted the Definition to point out that a OPD is not considered to be the origin of a circuit.
Appendix 15 is not an example of typical socket-outlet circuits.
It sets out options for the design of ring and radial final circuits for houshold and similar premises in accordance with Regulation 433.1, using socket-outlets and fused connection units.
I accept that an FCU meets the requirements of an OPD as far as the definition of a circuit is concerned.
However the particular circuits we are discussing, are final circuits, and the requirements for final circuits are not just restricted to the definition of a circuit in Part 2 and those of Regulation 433.1.
Regulation 314.4 states: Where an installation comprises more than one final circuit, each final circuit shall be connected to a separate way in a distribution board. The wiring of each final circuit shall be electrically separate from that of every other final circuit, so as to prevent the indirect energizing of a final circuit intended to be isolated."
Now unles you are suggesting that the FCU, the light, the fan and associated wiring are not a final circuit, or that an FCU is a distribution board; how can having the origin of a circuit being an FCU meet the requirements of Regulation 314.4?
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New builds are so much easier these days.
Live pair into a dual accessory box (mounted outside the bathroom) with one pair from the light, one pair from the pull switch and one 3 core from the fan back to the dual accessory box.
Live pair into the FCU (fused down to 3 amp), load pair out to the fan isolator with the light pair/switch pair/fan 3 core terminated into the fan isolator. No connector blocks, neat and tidy, job done. Simple.
The light remains on in the bathroom for maintenance to the fan when the fan isolator is off.
Isolate the load side of the FCU by removing the 3 amp fuse from the FCU for maintenance to the bathroom light/bathroom pull switch without the need to isolate any other lighting points connected to the the circuit supplying the bathroom lighting.
Live pair into a dual accessory box (mounted outside the bathroom) with one pair from the light, one pair from the pull switch and one 3 core from the fan back to the dual accessory box.
Live pair into the FCU (fused down to 3 amp), load pair out to the fan isolator with the light pair/switch pair/fan 3 core terminated into the fan isolator. No connector blocks, neat and tidy, job done. Simple.
The light remains on in the bathroom for maintenance to the fan when the fan isolator is off.
Isolate the load side of the FCU by removing the 3 amp fuse from the FCU for maintenance to the bathroom light/bathroom pull switch without the need to isolate any other lighting points connected to the the circuit supplying the bathroom lighting.
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J
JUD
Regulation 314.4 isn't what we're discussing here. That is separation of final circuits.
Nowhere have I said that an FCU is a distribution board. The supply side of the FCU is connected to a final circuit that is fed from a distribution board.
What I'm saying is that the cable coming off the load side of an FCU is it's own circuit with the BS 1362 fuse as it's protective device.
Let me ask you this. On a schedule of test results what would you enter as the protective device for the lights and fan in the bathroom. You couldn't put the one at the distribution board as that is not the primary protective device for that wiring. Therefore you would have to enter it as a separate circuit and the protective device would be BS 1362.
D
Deleted member 26818
We are discussing 314.4.
314.4 requires that where there is more than one final circuit, each final circuit must be supplied from a separate way at a distribution board.
If 'the cable coming off the load side of an FCU is it's own circuit', then what kind of a circuit is it?
If it is a final circuit, then it does not comply with BS7671, as it is not supplied from a separate way at a distribution board.
If it is a distribution circuit, then it must be supplying either a DB or switch gear.
Is it supplying a DB or switchgear, or is it some other kind of circuit which is not defined in BS7671?
When we test continuity of RFC conductors, we are required to record the highest measured value of R1+R2. The measurements are taken at each point on the RFC including any spurs, and the highest reading recorded.
We do not record the highest value measured on the RFC, and then list spurs as separate circuits and record their values separately.
As for your question, I would treat the whole circuit as one circuit, I would not attempt to separate the lighting circuit into two circuits, one for the lights and another for the bathroom light and fan.
As such I would list the lighting circuit protective device as the protective device.
D
Deleted member 26818
You can do that ezzzekiel, but I would expect it to be noted as a departure on any certification, and I would further expect you to ensure that it provides the same degree of safety as would be achieved by compliance with the Regulations.
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