Bathroom Fan

06-10-2014 6:54pm

Sir Arthur Daley wrote: »

What rules or regs are being breached by terminating in another cable into the switched side of the pull cord to power a contactor in an enclosure?

Assuming that the shower is an instantaneous type the cable will be at least a 6mm^2

That would mean installing a contactor fed by a 6mm^2 cable that supplies two separate 6mm^2 cables. This would require quite a large contactor to terminate the cables properly on the load side. If I had to do this I would use large d=DIN rail terminals & busbar. It is not likely that this would all fit in the distribution board and therefore an additional enclose would be required.

What you have described is not impossible task but it would be difficult to do in such a way that would comply fully with ET101:2008, be cost effective and practical.

The rules to look at in particular include:
● 133.2.1
● 133.2.3
● 134.1.1
● 134.1.4
● 134.1.5
● 433.1

I admit that my current sensing relay is not the most straight forward of solutions either, but it would cleaner and far more compact. I think that this simple problem is being over analysed. The simplest solutions are often the best, such as:
1) Feed a fan with an overrun timer from the light switch
2) Buy a quality humidity sensor and feed the fan from it.

Par1 · 06-10-2014 9:07pm

2011 wrote: »

Assuming that the shower is an instantaneous type the cable will be at least a 6mm^2

That would mean installing a contactor fed by a 6mm^2 cable that supplies two separate 6mm^2 cables. This would require quite a large contactor to terminate the cables properly on the load side. If I had to do this I would use large d=DIN rail terminals & busbar. It is not likely that this would all fit in the distribution board and therefore an additional enclose would be required.

What you have described is not impossible task but it would be difficult to do in such a way that would comply fully with ET101:2008, be cost effective and practical.

The rules to look at in particular include:
● 133.2.1
● 133.2.3
● 134.1.1
● 134.1.4
● 134.1.5
● 433.1

I admit that my current sensing relay is not the most straight forward of solutions either, but it would cleaner and far more compact. I think that this simple problem is being over analysed. The simplest solutions are often the best, such as:
1) Feed a fan with an overrun timer from the light switch
2) Buy a quality humidity sensor and feed the fan from it.

Well said 2011 hopefully this is the last post on this topic. Also the regulations are there as a guide to promote safety, the regs can not stipulate every circumstance that is why competence is recommended and insisted in the restricted works paper.

There are many reasons why the above should not be done and there is no point in stating any more regs (which we can do) instead lets bring this topic to a close and move on, as the original poster has more than enough recommendations at this point. Our time would be better spent advising people on other aspects of electrical queries and most importantly advising on Safe electrical practise. We will all make recommendations that another individual will query, that's productive criticism and the joy of asking opinions.

Next topic please!!
Cheers.

Sir Arthur Daley · 06-10-2014 11:12pm

2011 wrote: »

Assuming that the shower is an instantaneous type the cable will be at least a 6mm^2

Ok lets purpose use same cross section cable as shower cable to feed the coil on a contactor. The fan would be switched via the open contacts of the contactor.
Regardless of the economics or practicality of this proposal I don't believe its breaching any rules or regulations as other posters are suggesting.
Im open to correction on this.

06-10-2014 11:18pm

Sir Arthur Daley wrote: »

Regardless of the economics or practicality of this proposal I don't believe its breaching any rules or regulations

Agreed, it would be possible to do this and fully comply with the rules (I said this in my last post). However it would not make sense on any level.

mikeyjames9 · 06-10-2014 11:21pm

Sir Arthur Daley wrote: »

Ok lets purpose use same cross section cable as shower cable to feed the coil on a contactor. The fan would be switched via the open contacts of the contactor.
Regardless of the economics or practicality of this proposal I don't believe its breaching any rules or regulations as other posters are suggesting.
Im open to correction on this.

it's a bad idea attempting to use shower isolating switch as a means of switching a fan

the switch is liable to give trouble when you break into it with new wiring or the consumer starts using it as a fan on/off switch

I don't think there's any specific reg against it

occupancy sensor or the other automatic methods, flow switch or current sensor(in DB) are preferable if the humidistat doesn't work properly

Sir Arthur Daley · 06-10-2014 11:25pm

I agree its not the best idea, just want to resolve the issue that another posters say its against regulation.
Its bad enough if one gives advice and its incorrect but alot worse giving correct advice and being told its incorrrect. Causes alot of confusion for nothing.

Par1 · 07-10-2014 6:55pm

That is why the words 'Competent' is used a lot now in describing electricians as qualifications can lead people to think 'Oh hes an electrician, he must know his stuff' - not necessarily in some circumstances. Give me competence over qualification any day but competence combined with qualification is really the key i think.

mikeyjames9 · 07-10-2014 9:19pm

using an appliance isolating switch for control/switching of another device

now that I think of it there definitely should be a regulation against it, if there isn't already

Sir Arthur Daley · 07-10-2014 9:23pm

mikeyjames9 wrote: »

using an appliance isolating switch for control/switching of another device

now that I think of it there definitely should be a regulation against it, if there isn't already

A single cooker switch feeding a seperate oven and hob is widely a case of this.

mikeyjames9 · 07-10-2014 9:25pm

Sir Arthur Daley wrote: »

A single cooker switch feeding a seperate oven and hob is widely a case of this.

That's a common (shared) isolating switch

A different matter

07-10-2014 9:26pm

mikeyjames9 wrote: »

using an appliance isolating switch for control/switching of another device

now that I think of it there definitely should be a regulation against it, if there isn't already

What is your concern?

I don't see why this would be dangerous or in breach of any regulation if done correctly.

mikeyjames9 · 07-10-2014 9:34pm

2011 wrote: »

What is your concern?

I don't see why this would be dangerous or in breach of any regulation if done correctly.

It's just bad practice imo

"separate isolating switch " for an appliance should only serve to isolate the supply to the appliance/s and not control of other devices

07-10-2014 9:39pm

mikeyjames9 wrote: »

It's just bad practice imo

"separate isolating switch " for an appliance should only serve to isolate the supply to the appliance/s and not control of other devices

The shower will be safely isolated by the isolator.
The fan can still have a dedicated local isolator.
All poles of both devices can be safely isolated by a local isolating device, that is the important bit.

I think that this is a strange and not very practical solution, but it can work safely.

Do you have a particular safety concern?

mikeyjames9 · 07-10-2014 9:39pm

What will happen if that starts up is someone thinks

Hey, I'll wire the fan and shower cubicle lighting from the shower isolator

That's a cool idea

So next thing you know you have to work in the dark if you need to fix the slower

07-10-2014 9:47pm

mikeyjames9 wrote: »

What will happen if that starts up is someone thinks

Hey, I'll wire the fan and shower cubicle lighting from the shower isolator

That's a cool idea

So next thing you know you have to work in the dark if you need to fix the slower

That has nothing to do with this thread.
Besides electricians often have to arrange temporary lighting, its really not that difficult.

Sir Arthur Daley · 07-10-2014 9:56pm

Maybe my idea for the op is making more sense than its credited for. Its a solution to his problem.

mikeyjames9 · 07-10-2014 9:58pm

2011 wrote: »

That has nothing to do with this thread.
Besides electricians often have to arrange temporary lighting, its really not that difficult.

It has everything to do with

In the example being discussed

The shower isolating switch is proposed as a method of controlling/switching a seperate device

If this was a good idea there would be everyday examples of this

There are none

07-10-2014 10:04pm

mikeyjames9 wrote: »

If this was a good idea there would be everyday examples of this

I never said it was a good idea!
In fact I said quite the opposite.

In post 32 I said "What you have described is not impossible task but it would be difficult to do in such a way that would comply fully with ET101:2008, be cost effective and practical" and in post 44 I said "I think that this is a strange and not very practical solution".

However that does not mean that it would be dangerous or in breach of ET101.

Par1 · 07-10-2014 10:53pm

Id agree with mikeyjames9 with posts 39 41 and 43

08-10-2014 8:36am

Par1 wrote: »

Id agree with mikeyjames9 with posts 39 41 and 43

I agree that it is not a good solution (for many reasons).

But the fact remains; so far nobody has been able to say why it would be dangerous or against the regulations.

I would still go with one of my earlier solutions:
1) Feed a fan with an overrun timer from the light switch
2) Buy a quality humidity sensor and feed the fan from it.

mikeyjames9 · 08-10-2014 12:24pm

2011 wrote: »

I agree that it is not a good solution (for many reasons).

But the fact remains; so far nobody has been able to say why it would be dangerous or against the regulations.

I would still go with one of my earlier solutions:
1) Feed a fan with an overrun timer from the light switch
2) Buy a quality humidity sensor and feed the fan from it.

It's self evident that an appliance local isolator should not be used to switch/control a separate device

I doubt et101 even deals with these situations

"Separate isolating switch " implies it is solely for isolation of supply to appliance imo

Par1 · 08-10-2014 6:21pm

2011 wrote: »

I agree that it is not a good solution (for many reasons).

But the fact remains; so far nobody has been able to say why it would be dangerous or against the regulations.

I would still go with one of my earlier solutions:
1) Feed a fan with an overrun timer from the light switch
2) Buy a quality humidity sensor and feed the fan from it.

Mikeyjames9 suggested earlier that wiring off the pullcord was against regulations and hes right, its a bad way of doing things. The shower could pull 8500-9500 watts..imagine the PSCC ?? and people then suggest to link that to a contactor/fan equipment?''its nonsense...the fan should be supplied through a suitable RCD and with suitable cable, accessories and safe practice.

Sir Arthur Daley · 08-10-2014 6:27pm

This is getting very confusing and unfair on the op as one side saying its against regulation and another saying its not. Can documentation be produced to verify this as stating something that is not true is not right.

08-10-2014 8:13pm

Par1 wrote: »

Mikeyjames9 suggested earlier that wiring off the pullcord was against regulations and he's right

Please direct me to the regulation that states this.
Any comments on regulation 555.3.3 which permits this?

its a bad way of doing things.

My words were "a strange and not very practical solution" but nobody can point to why this would be either unsafe or in breach of any rules in ET101:2008

The shower could pull 8500-9500 watts..imagine the PSCC ??

The PSCC (Prospective Short Circuit Current) of the shower has nothing to do with the kW rating of the shower. It is calculated by dividing the nominal voltage (230V) by the earth fault loop impedance (Ohm's Law).

The advantage of a low earth fault loop impedance is a high PSCC which will cause the protective device to operate quickly. Problems occur when PSCC exceeds the breaking capacity of the upstream equipment (protective devices, busbars etc.....). However none of this has anything to do with feeding a contactor from a shower isolator.

I would be interested to hear your concern.

people then suggest to link that to a contactor/fan equipment?

A 8.5kW shower will draw about 37 amps.
The coil of an contactor consumes about 3W so it will draw about 13mA
See link.

Is your concern that the additional current consumed by the coil will cause the cable to fail??

''its nonsense...the fan should be supplied through a suitable RCD and with suitable cable, accessories and safe practice.

Agreed, my interpretation is that is the plan.
The proposal is that the shower is supplied from a (for example) 40A RCBO.
The fan is supplied from a different circuit (for example) 10A RCBO.

Switching on the isolator provides a control signal to the coil of the contactor. This energises the contactor brining power to the fan (from a separate circuit).

If the shower supply cable (at least 6 sq.) has overload & short circuit protection from the 40A RCBO.
The fan cable (at least 1.5 sq.) has overload & short circuit protection from the 10A RCBO.
The cable feeding the coil of the contactor (at least 1.5 sq. ) can be fed from a 500mA fuse providing it with overload & short circuit protection.

The fan can have a dedicated local isolator so that it complies with the regulations.

Have a look at page 138 of ET101:2008. Regulation 555.3.3 states "It is permissible to supply auxiliary equipment associated with water services and water systems from the circuit supplying a water-heating appliance".

The shower is a "water-heating appliance" and the contactor is "auxiliary equipment".

I have found a regulation permitting this, but we have yet to find a regulation that would be breached.

555.5 page 139 deals with extraction fans. Nothing mentioned here that suggests that there would be any issues.

Par1 · 08-10-2014 9:53pm

The regulations clearly state "Every appliance shall be provided with a SEPERATE isolating switch complying with 537.2 and capable of interrupting the load current. The device shall be installed within 2m, at a height between 400mm and 600mm above floor level, and where it can be operated without danger". - 555.1.2

Therefore in my opinion (i stand to be corrected on this) the idea of wiring two electrical appliances (shower and fan) from the one pullcord isolation switch is not allowed under the above regulation.

08-10-2014 10:13pm

Par1 wrote: »

The regulations clearly state "Every appliance shall be provided with a SEPERATE isolating switch complying with 537.2 and capable of interrupting the load current. The device shall be installed within 2m, at a height between 400mm and 600mm above floor level, and where it can be operated without danger". - 555.1.2

Therefore in my opinion (i stand to be corrected on this) the idea of wiring two electrical appliances (shower and fan) from the one pullcord isolation switch is not allowed under the above regulation.

The fact is that the isolation switch for the shower isolates the shower, it does not isolate the fan. The action of turning off this isolator removes power from the fan, but this would not be considered a proper or "full electrical isolation".

For example:
An electrician wants to disconnect a motor fed from a DOL starter. If he were to activate the emergency stop this would cause the contactor to de-energise and the motor would stop. However the motor would not be considered to be safely electrically isolated to the point that the motor can be disconnected. No work permit or method statement could be signed off in this case. The HSA would have a field day. Normally in this situation the local isolator would be locked off (at a minimum). The same in this case, the isolator local to the fan should be turned off prior to work commencing on the fan (that is the purpose of the isolator).

Sir Arthur Daley · 08-10-2014 10:21pm

What about the other suggestion i had for the op where a 230 volt supply be got from the shower unit itself to energise a contactor which in turn switches on the fan.
Put aside the warranty issue by splicing into the shower internal wiring is there any other issue one can foresee?

Par1 · 08-10-2014 10:32pm

2011 wrote: »

The fact is that the isolation switch for the shower isolates the shower, it does not isolate the fan. The action of turning off this isolator removes power from the fan, but this would not be considered a proper or "full electrical isolation".

For example:
An electrician wants to disconnect a motor fed from a DOL starter. If he were to activate the emergency stop this would cause the contactor to de-energise and the motor would stop. However the motor would not be considered to be safely electrically isolated to the point that the motor can be disconnected. No work permit or method statement could be signed off in this case. The HSA would have a field day. Normally in this situation the local isolator would be locked off (at a minimum). The same in this case, the isolator local to the fan should be turned off prior to work commencing on the fan (that is the purpose of the isolator).

It does isolate the shower and fan if you connect into the load side because the fan or shower will not have supply when pullcord is 'Off' - Isolated from supply.

Regardless of position of any additional Fan isolaters or contactors the regulation clearly states every appliance 'Shall Be Seperately Isolated' as in 1 isolator per appliance. In this case the shower isolator would be isolating 2 appliances the fan and the shower- therefore they are not separaated because they are linked both at the pullcord.

I agree with you what you say regarding the motor example but that is a different scenario.

08-10-2014 10:48pm

Par1 wrote: »

It does isolate the shower and fan if you connect into the load side because the fan or shower will not have supply when pullcord is 'Off' - Isolated from supply.

There is a difference between a de-energised contactor powering down a device and an isolator interrupting the supply to a device. This difference is recognised throughout the industry. This is why isolators are ferquently installed local to motors even when they are fed from local contractors.

Regardless of position of any additional Fan isolaters or contactors the regulation clearly states every appliance 'Shall Be Seperately Isolated' as in 1 isolator per appliance.

There is a seperate isolator for the shower and a seperate isolator for the fan. In my opinion this meets the requirements.

Let's not forget a single cooker switch can be used to isolate an oven and a hob.

In this case the shower isolator would be isolating 2 appliances the fan and the shower- therefore they are not separaated because they are linked both at the pullcord.

Correction, in this case the shower isolator would isolate the shower. The supply to the contactor for the fan would still be live. The fan would not be considered to be electrically isolated. On an industrial installation an electrician found working on a fan in this state would be likely to be removed from site. There are strict rules that govern isolations.

I agree with you what you say regarding the motor example but that is a different scenario.

I will take that as a positive

Why should this be treated any differently?
Both scenarios are very similar:
In both cases it is a contactor (which have a far higher failure rate than isolators) in a de-energised state with a live 230VAC supply on one side connected a motor.

Par1 · 08-10-2014 11:12pm

Regardless of anything (other examples are irrelevant)...the wires inside the shower pullcord are electrically linked to 2 appliances therefore not complying with the regulation.

To put this simple a shower pull cord can only be used to isolate the shower- one pullcord one shower. If you adapt any other element into this setup by addition of any other appliance direct or indirect, you are then not complying with regulation 555.1.2 (In my opinion)

Bathroom Fan

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