Bathroom Wiring - D Skelton - Other Interpretations.

[D Skelton]

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Off topic debate with reference to original thread :- 

http://talk.electricianforum.co.uk/topic/25971-bathroom-wiring/page-0

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Also manufacturer's instructions ask for a 3A fuse backing up the fan

Only a small few. Anyway, come January, who cares? They've done away with having to follow manufacturers instructions, not that I follow them religiously now anyway. Half of the time they're poor at best.

seperate from the lighting

Wrong. It doesn't have to be seperate from the lighting.

but you'll still need a 3 pole isolator as well .

Again, wrong, unless manufacturers instructions specically state this.

These are all very common myths that have been introduced to the electrician's lexicon by a book known as 'The Electricians Guide to the Building Regulations'. It's all a load of gumpf and has no grounding in BS 7671 whatsoever.
 

Edit: Just read back through that post and it comes across as really patronising. It isn't meant in that way at all, I'm just bugged by myths that are still presenting themselves today.

 

[Manator]

There are indeed many myths, and bad practice, both of which have an impact on what we do. Often out of habbit, sometimes out of neglect.

Manufacturers instructions are followed in order to maintain the responsibility for continued use on the manufacturer and not the installer. They all have a disclosure that it also requires installing by a competent person, and to the wiring regulations.

I have just done three hospital jobs where I had to change the wiring and add extra protection for three machines not installed to the instructions. These were installed less than a year ago. They failed on warranty because they were not installed correctly.

Any advise given on any forum should be taken as seen, and should never be considered right until you have researched further.

 

[D Skelton]

It is down to us as professional electricians to determine what is best according to the regulations we have to follow when installing a particular item of equipment, whether that be 7671 or any other set of regs. The fact is, I, as I'm sure you have as well, have come across many sets of instructions that are just nonsense. As an example, a little while back I was connecting up a couple of TP ovens in a small commercial kitchen I had rewired, I can't remember word for word but the instructions said something along the lines of "To comply with BS EN 7671, this oven must be protected by a 30mA RCD"???

So basically, the instructions were wrong, in more ways than one, but BS 7671 still calls for me to follow them???

I didn't RCD protect them by the way. Strike me off the register!!! lol

 

[SPECIAL LOCATION]

I didn't RCD protect them by the way. Strike me off the register!!! lol

I thought you were already off the register by now?????

Like I said, I'm a paid up member until April, if I leave now I don't get any money back, so I will continue to use their colourful (but meaningless) logo on my website until renewal!

Post #23 here...

http://talk.electricianforum.co.uk/topic/25353-save-our-trade/page-2

:C  

 

[D Skelton]

I thought you were already off the register by now?????

Haha, yes, my subscription will not be renewed. As I'm sure you can see, there is nothing linking my business to any scam scheme whatsoever now. I am however still technically registered until the end of June.

 

[M107]

but you'll still need a 3 pole isolator as well .

Again, wrong, unless manufacturers instructions specically state this.

If the supply is TT you'll be in the wrong & you'll be wanting to think about 537.3.1.1...............isolation for maintenance of a fan I was asked about on an assessment.

seperate from the lighting

Wrong. It doesn't have to be seperate from the lighting.

I suspect Deke wasn't meaning the 3A fuse was off a separate supply, I would take a guess he meant the 3A fuse protects the fan & only the fan.............if it's a timer over run fan you'll want 2x 3 amp fuses.

Also manufacturer's instructions ask for a 3A fuse backing up the fan

Only a small few. Anyway, come January, who cares? They've done away with having to follow manufacturers instructions, not that I follow them religiously now anyway. Half of the time they're poor at best.

If equipment goes wrong & I've not followed manufacturers instructions, I as the installer am liable for the replacement costs, that's how it goes on some of the school work I do; & that's what happens to contractors for the FRS, after I'm asked to check out the installations when equipment packs up/goes wrong or is part of a near miss investigation.

So the advocation  of not following manufacturers instructions is in my opinion plain and simple WRONG. 

 

[D Skelton]

If the supply is TT you'll be in the wrong & you'll be wanting to think about 537.3.1.1...............isolation for maintenance of a fan I was asked about on an assessment.

Nope, I wouldn't. On a TT system, there will be a double or four pole linked switch at the origin of the installation that can be used for isolation (including the neutral), if that is what the fan requires. As for 537.3.1.1, this calls for a means of switching off, not isolation.

 

[Evans Electric]

Only a small few. Anyway, come January, who cares? They've done away with having to follow manufacturers instructions, not that I follow them religiously now anyway. Half of the time they're poor at best.

Wrong. It doesn't have to be seperate from the lighting.

Again, wrong, unless manufacturers instructions specically state this.

These are all very common myths that have been introduced to the electrician's lexicon by a book known as 'The Electricians Guide to the Building Regulations'. It's all a load of gumpf and has no grounding in BS 7671 whatsoever.

Edit: Just read back through that post and it comes across as really patronising. It isn't meant in that way at all, I'm just bugged by myths that are still presenting themselves today.

It certainly does come across as patronising  Mr Skelton .

I'm sure you must realise that I'm NOT advocating a SEPERATE CIRCUIT for a poxy bathroom fan but in fact ,  a seperate fuse ,  seperate from the lighting circuit protective device from whence it attains it's supply .   Most maker's instructions are asking for this in my experience.

You must also know that because bathroom fans have in general, a timed override facility which is  triggered by the switched side of the lighting and the Regs ask for such items to have local isolation ...a 3 pole switch is usually required to render said appliance brown bread for maintenance purposes. 

Switching off your imaginary 4 pole linked main switch to isolate a bathroom fan is, at the very least , derisable , not necessary and utterly ridiculous.

The following applies with bathrom fans :- 

1)   Their own fuse hopefully keeps the lights on when the fan craps out .

2)   Fan needs isolation of   Live feed/  Trigger Switch wire / Neutral .  ( 3 pole)

3)   Fans are likely to be cleaned etc by untrained persons .

4)   The link to the light switchwire is to overcome the reliance of  people switching it on & off so giving it a semi automatic operation to comply with  

      Building Regs.

 

[Bruspark]

Worse still switching off the 4 Pole linked TT mains switch renders the owners kettle unable to produce tea at a time appropriate to the completion of a quick fan swap.   Not sure which reg that one is but it's definitely a problem in my 'on-site-guide'  :B-

 

[D Skelton]

I suspect Deke wasn't meaning the 3A fuse was off a separate supply, I would take a guess he meant the 3A fuse protects the fan & only the fan.............if it's a timer over run fan you'll want 2x 3 amp fuses.

I know what he meant, like you say, that the fuse protects the fan only. Why? If you were fitting a fan that required fusing down (god knows why as the fuse only protects the cable and not the equipment it feeds) you would be more than able to fuse down the bathroom light that the fan is fed from with a single fuse.

If equipment goes wrong & I've not followed manufacturers instructions, I as the installer am liable for the replacement costs, that's how it goes on some of the school work I do; & that's what happens to contractors for the FRS, after I'm asked to check out the installations when equipment packs up/goes wrong or is part of a near miss investigation.

So the advocation  of not following manufacturers instructions is in my opinion plain and simple WRONG.

I did't advocate not following them, I said we as professionals have to make informed decisions as to whether or not we follow them and to what degree. In the case of manufacturers instructions that are just wrong or plain stupid, why would you just blindly follow them in order to comply with the regs but at the same time risk not complying with the regs at the same time?!?! The departure section on the EIC is there for a reason, I'm well within my right to put in there that the manufacturers instructions for appliances X, Y and Z have not been followed because of reasons A, B and C. If following manufacturers instructions was so important, why are they removing this clause from the 3rd ammendment in January?

Answers in red

 

[Steve3948]

I think most fans today say from a lighting circuit or a 3A fuse, the reason for the 3A being if installed on a circuit other than a lighting circuit.

A 6A Mcb Type B will most likely go before a 3A cartridge fuse.

 

[Evans Electric]

Worse still switching off the 4 Pole linked TT mains switch renders the owners kettle unable to produce tea at a time appropriate to the completion of a quick fan swap.   Not sure which reg that one is but it's definitely a problem in my 'on-site-guide'  :B-

Its Code of Practice,  Bruspark,  a clip-on platform is avaliable , attaches to the shower rail to rest your cuppa tea on , within reach of the fan replacement operation . 

 

[D Skelton]

It certainly does come across as patronising  Mr Skelton .

Like I said, my frustration was not aimed at you

I'm sure you must realise that I'm NOT advocating a SEPERATE CIRCUIT for a poxy bathroom fan but in fact ,  a seperate fuse ,  seperate from the lighting circuit protective device from whence it attains it's supply .   Most maker's instructions are asking for this in my experience.

Yes, I knew exactly what you meant, I've just answered this in my previous reply. In my rather limited experience (I only install ventillation gear made by two different manufacturers) they don't always call for fusing down. I know there are some that do, even still, if the manufacturer wants their equipment fusing down, why are they not providing internal fuses? The fact is, an OCPD is only there to protect the cable feeding the equipment, not the equipment itself.

You must also know that because bathroom fans have in general, a timed override facility which is  triggered by the switched side of the lighting and the Regs ask for such items to have local isolation ...a 3 pole switch is usually required to render said appliance brown bread for maintenance purposes. 

The regs make no mention of local isolation, again, this is just a made up term from various books. What the regs do call for is a readily accessible means of switching off with regards to a fixed electric motor. This can be accomplished in many ways other than a three pole isolator.

Switching off your imaginary 4 pole linked main switch to isolate a bathroom fan is, at the very least , derisable , not necessary and utterly ridiculous.

That was in reference to the post about isolation on a TT system which requires that the neutral be isolated as well. Tell me, how would you fully isolate, in compliance with the regulations, any circuit on a TT system without either flipping one of the RCDs or the main switch? Unless you have DP RCBOs on every circuit, it can't be done.

The following applies with bathrom fans :- 

1)   Their own fuse hopefully keeps the lights on when the fan craps out .

Why don't we just fuse down every single luminaire then? Every light should be individually fused down to 3A so that one lamp failing won't trip the circuit breaker?

2)   Fan needs isolation of   Live feed/  Trigger Switch wire / Neutral .  ( 3 pole)

The OCPD for the circuit achieves this perfectly, unless as previously stated the installation is TT and the OCPD isn't a DP RCBO.

3)   Fans are likely to be cleaned etc by untrained persons.

Light bulbs are likely to be changed by untrained persons

4)   The link to the light switchwire is to overcome the reliance of  people switching it on & off so giving it a semi automatic operation to comply with  

      Building Regs.

I don't quite understand this, could you rephrase please

In red

 

[Bruspark]

HaHA EE      Yes but Time for Tea to cool exceeds Time to write receipt so Time to turn kettle on must be before Time to turn 4 pole isolator on.    Result is lost time /burnt tongue / too much information on weather, cats, and how their mate was going to fix it for nothing 

 

[D Skelton]

 
I have to say i don't do domestic AT ALL 

But anyone in my honest opinion that relays on a 2/4pole isolator at the origin to isolate something as simple as a bathroom fan should go back to school and learn how to be diligent and do things properly (regs aside) - its just common sense

I am wiring a 400kW ac water cooled motor and inverter in July - Retrofit for a DC system - on the same note do you think I should rely on the main incoming isolator that isolates the sub from the machine panels (there are a few) to isolate this motor for maintenance ? I know its on a larger scale but the principle is the same as has been suggested....

Its no wonder the Industry is on its knees and we seem to be overrun by.......

:facepalm:   :innocent   :slap   :C   :C   :C

Like I said before, on a TT system double pole isolation is required for every item of current using equipment. Unless every OCPD is a DP RCBO or MCB, how do you expect to achieve this? This doesn't just apply to bathroom fans but everything in the installation. You gonna fit DP isolation on everything???

The industry is on it's knees because too many people are more than willing to accept what they're told by some private training provider or by some £7.99 book as gospel.

 

[Andy™]

The industry is on it's knees because too many people are more than willing to accept what they're told by some private training provider

well that 5 week short course you done was a bit of a waste then, wasnt it?

 

[D Skelton]

It was a five day one actually.

You gonna be constructive here at all?

well that 5 week short course you done was a bit of a waste then, wasnt it?

I dont do domestic but if i did then to achieve this i would fit an SBS board with DP RCBOS on every circuit for a TT system - Common sense really ? Do you fit DP RCBOS on TT systems ? 

And you avoiding what you stated - bit like a politician really

Domestic? No, dual RCD with a seperate type-s up front. Commercial, DP OCPDs every time.

Sorry, what am I avoiding?

 

[Manator]

I have just done a TT install with two distribution boards, single point isolation and double pole rcbo's.

 

[D Skelton]

Ill leave that for you to work out :slap

400kW motor??

 

[D Skelton]

Thats your opinion and in my opinion thats not correct - but that could be debated all year and no-one would be correct msl1:

You're right, to be fair, what I said is only just scratching the surface as to why the industry is on it's knees, but there are times and places for those debates and yes, the argument would only end up going round in circles.