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SELV - Not a fan of?
whjohnson 11001209847
301 Posts
Question
Short question - is a mains voltage extractor fan permissible in zone 1 or 2 in a bathroom provided it is protected by a 30ma rcd and that all IP requirements are met??
OSG chapter 8, Table 8.1, page 94 says only 25vAC or 60v ripple-free DC SELV or PELV, yet I have just been to the wholesalers to look at what they have, and they showed me two mains fans with "Suitable for" or "Complies with" Zone 1 emblazoned on the packaging.

I am looking to fit a fan with a humidistat but am struggling to find a SELV version if that is actually required.
So, which is correct? The manufacturer (whose instructions must be followed) or the on site guide, whose instructions must also be followed!

Comments welcome.

 
11 Replies
AJJewsbury 77361768
1622 Posts
230V ventilation equipment is permitted in zone 1 if the manufacturer says its suitable in their instructions (reg 701.55) (plus all the usual requirements for IP rating, 30mA RCDs, supplementary bonding etc apply)

Earlier regs did differ on the requirements though - it might be your OSG is out of date? (or a latest copy has out of date information?)

   - Andy.
whjohnson 11001209847
301 Posts
My OSG is the 18th ed. I reckon I'll go the SELV route to be on the safe side - it is nearly 3 times more expensive but at 60 years of age I want to coast safely to retirement and not have to stand in front of a man with a white wig simply because the wiring regs have become too woolly to follow these days!
Farmboy 11001209268
176 Posts



In the current-using equipment column of that table, the zone 1 row goes on to say the following mains voltage fixed, permanently connected equipment allowed:... ventilation equipment... So will that not include 230V fans?

Also, the OSG is a guide, so is it that which 'must' be followed?

F
gkenyon 82239607
1047 Posts
As Andy has pointed out, Regulation 701.55 clearly says "ventilation equipment" is permitted in Zone 1, specifically listed as item (viii), provided the manufacturer says it's suitable for installation in Zone 1. It does not have to be SELV, but 701.411.3.3 requires a 30 mA RCD for additional protection.

Any switchgear and accessories for the fan, however, would have to go outside the zones (not even permitted in Zone 2).

Table 8.1 on the 2018 OSG that you highlighted, in Zone 1, column 3, after SELV/PELV sentence, has another sentence about which mains powered fixed equipment is permitted - and ventilation is, as Farmboy has pointed out, clearly listed. The 4th column only refers to swtichgear and accessories - and as I have pointed out, if mains, the switchgear and accessories (fan isolator, other switches, FCU etc as applicable to how you're wiring up) would have to go outside zones.
whjohnson 11001209847
301 Posts
Also, the OSG is a guide, so is it that which 'must' be followed?

I have often found myself asking that very same question!
gkenyon 82239607
1047 Posts
whjohnson:
Also, the OSG is a guide, so is it that which 'must' be followed?

I have often found myself asking that very same question!

There is a "precedence" in legal terms

  1. Legislation: you have to whether you like it or not
  2. Approved Codes of Practice / Approved Documents: Well, if you don't follow them (particularly the HSE ones), you have to prove in court you did something at least as safe. This is a little counter to the "innocent until proven guilty" premise, but it's there in legislation all the same, and has been for too many years for anyone to say it's unfair.
  3. British Standards: Can be used in court as evidence. (What they don't explicitly say, is that it's evidence by BOTH sides, prosecution and defence).
  4. Industry Guidance ... is just that, good practice. But well worth doing all the same, because it might avoid any issues with 1 to 3 above, provided it doesn't conflict.
Farmboy 11001209268
176 Posts
gkenyon:
whjohnson:
Also, the OSG is a guide, so is it that which 'must' be followed?

I have often found myself asking that very same question!

There is a "precedence" in legal terms

  1. Legislation: you have to whether you like it or not
  2. Approved Codes of Practice / Approved Documents: Well, if you don't follow them (particularly the HSE ones), you have to prove in court you did something at least as safe. This is a little counter to the "innocent until proven guilty" premise, but it's there in legislation all the same, and has been for too many years for anyone to say it's unfair.
  3. British Standards: Can be used in court as evidence. (What they don't explicitly say, is that it's evidence by BOTH sides, prosecution and defence).
  4. Industry Guidance ... is just that, good practice. But well worth doing all the same, because it might avoid any issues with 1 to 3 above, provided it doesn't conflict.



Appreciate the analysis and confirmation. In short, do what they say, unless you're qualified and experienced enough to do otherwise, but be able to prove that any deviation is as safe or safer. That excludes me then, so I'll treat the OSG and GN's as the last word. 

Thanks

F

whjohnson 11001209847
301 Posts
A quite bizarre experience - I had the wholesaler - ex electrician - telling me that a 230v fan was acceptable in zone 1, then I had the OSG giving me mixed messages about DC ripple & SELV only  It all seemed to be couched in a non-committal kind of style with plenty of only ifs, but 's & maybes to the point whereby it may as well have been an eu directive drafted by a pub lawyer.
Why can't the requirements be more prescriptive whereby they leave the reader in no doubt as to what is actually required and what will actually comply?

I could carry out the installation in 2 ways, mains, then SELV and invite as many seasoned 'inspectors to check each  one, and you can bet that neither installation method will satisfy all of the inspectors at the same time, such of the inconsistency of the message. Meanwhile I am attempting to do my bets by following the wiring regulations and the manufacturer's instructions (as demanded by the wiring regulations) and am sensing conflict between the two - no, not full conflict, but slight friction. So I fit a 230v fan in zone 1 and someone is fatally electrocuted, despite the manufacturer's zone 1 compatability claims. Their prosecution rep will be all over the wording of the OSG like a tramp on a tray of silt chips. I can see it now - "Best of your knowledge and ability sir? But you didin't follow the wiring regulations, specifically...........and I have an expert witness here to prove it"
.

 
AJJewsbury 77361768
1622 Posts
Their prosecution rep will be all over the wording of the OSG like a tramp on a tray of silt chips. I can see it now - "Best of your knowledge and ability sir? But you didin't follow the wiring regulations, specifically...........and I have an expert witness here to prove it"
Thankfully the wiring regulations themselves (i.e. BS 7671) are reasonably clear - and do currently allow 230V fans in zone 1 (with the provisos) - so you should be able to sleep soundly on that point.

No expert witness in their right mind would refer only to some other document (like the OSG) if the alleged job in hand is to show lack of compliance with the wiring regs.

     - Andy.
Chris Pearson 11001208764
1467 Posts
gkenyon:
whjohnson:
Also, the OSG is a guide, so is it that which 'must' be followed?

I have often found myself asking that very same question!

There is a "precedence" in legal terms

  1. Legislation: you have to whether you like it or not
  2. Approved Codes of Practice / Approved Documents: Well, if you don't follow them (particularly the HSE ones), you have to prove in court you did something at least as safe. This is a little counter to the "innocent until proven guilty" premise, but it's there in legislation all the same, and has been for too many years for anyone to say it's unfair.
  3. British Standards: Can be used in court as evidence. (What they don't explicitly say, is that it's evidence by BOTH sides, prosecution and defence).
  4. Industry Guidance ... is just that, good practice. But well worth doing all the same, because it might avoid any issues with 1 to 3 above, provided it doesn't conflict.

Wise words from Graham, but there is also a nuanced difference between an HSE ACOP and HSE legal advice. If you are prosecuted under H&S law and it is shown that you have failed to follow an ACOP, there is a rebuttable presumption of guilt. In other words, you have to show that what you did was safe; it is not for HSE to show that it was unsafe.

However, as far as the legal advice is concerned, you do not have to follow it, but if you did, there is a presumption of innocence.

This is how HSE puts it.

gkenyon 82239607
1047 Posts
whjohnson:
A quite bizarre experience - I had the wholesaler - ex electrician - telling me that a 230v fan was acceptable in zone 1, then I had the OSG giving me mixed messages about DC ripple & SELV only  It all seemed to be couched in a non-committal kind of style with plenty of only ifs, but 's & maybes to the point whereby it may as well have been an eu directive drafted by a pub lawyer.
Why can't the requirements be more prescriptive whereby they leave the reader in no doubt as to what is actually required and what will actually comply?

I could carry out the installation in 2 ways, mains, then SELV and invite as many seasoned 'inspectors to check each  one, and you can bet that neither installation method will satisfy all of the inspectors at the same time, such of the inconsistency of the message. Meanwhile I am attempting to do my bets by following the wiring regulations and the manufacturer's instructions (as demanded by the wiring regulations) and am sensing conflict between the two - no, not full conflict, but slight friction. So I fit a 230v fan in zone 1 and someone is fatally electrocuted, despite the manufacturer's zone 1 compatability claims. Their prosecution rep will be all over the wording of the OSG like a tramp on a tray of silt chips. I can see it now - "Best of your knowledge and ability sir? But you didin't follow the wiring regulations, specifically...........and I have an expert witness here to prove it"
.

 

I'm not sure I agree with you about the OSG, but as others have said, it's BS 7671 that really matters, and that is quite clear. There are indeed different requirements for switchgear and controlgear to fixed current-using equipment (to socket-outlets) in the zones ... as there have been for a long time.

The OSG does not conflict - but if you can let the Forum know what's unclear for you in the OSG, perhaps we can help with that.


I've picked up a 20-year old 16th Edition, and a the 2008 and 2011 17th Editions, and not a great deal has changed with respect to either switchgear/controlgear or current-using equipment in Zone 1, save that the 17th and 18th Edition requirements seem a lot clearer with regard to the sorts of mains-powered current using equipment that's likely to be suitable in Zone 1

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