Domestic smoke alarms on pay-as-you-go meter

[lyledunn]

A large local housing authority has dictated that no smoke alarm system should be supplied via a pay-as-you-go type meter. Perhaps a reasonable diktat with respect to effective fire alarm function for Grades A-C but perhaps a little unreasonable for Grade D systems where battery back-up is of the order of years! It is very restrictive for many tenants and indeed landlords who would much prefer the pay-as-you-go type of meter. Does any one know if this requirement is common or do you have any opinion? Really would appreciate your comments.

[Midland Retty]

Hi Lyle

Detectors should be powered from the landlords supply and I would never advise anything different.

In the case of mains powered detectors fitted with 10 year lithium batteries you could argue the toss I suppose. So long as the battery could not be easily removed (generally they are not when it comes to lithium battery models) then you may be able to justify having them connected to the tenants supply, but it doesn't rest easy with me.

[lyledunn]

Thanks for the reply Midland Fire and I accept your points. When served from the landlords supply you then have 230v detectors that are not fed through the isolator in the consumer unit in the flat. This could introduce problems complying with BS7671 2008 and is generally an undesireable situation from an electrical safety perspective. I have pointed this out to the housing authority and they have asked for notices to be placed at the flat consumer units. Unfortunately, folk have become almost blind to warning notices as they seem to an omnipresence in modern life.

[kurnal]

I guess the Housing Authority know their tenants and their behaviour?

There are no stipulations in BS5839-6 with regard to a Grade D system,  preventing the smoke alarms being powered from the consumer side of a pre payment meter. I agree it is far less than ideal but must be considered a tolerable risk as the BS is specific in precluding it for a grade A/B system but makes no mention of it in respect of Grade D.   

[colin todd]

Oh how naive Big Al.  it is not considered a tolerable risk. it is just we never thought of it. it is a well-known issue.

[kurnal]

Interesting response as always Colin.
If it is not considered a tolerable risk what are we doing about it?
Government statistics indicate that 14% of homes in the uk, and up to 28% in NI use pre payment meters. Roughly 4 million dwellings.
Would you agree that if it is a risk, then it is potentially a risk all dwellings with pre payment meters, whether houses or flats? And that only the occupiers of the dwelling are at risk as a result?
The risk will only arise when there is no credit on the meter and the battteries/ capacitor have discharged as a result. In void dwellings no-one is at risk (though the batteries may be badly affected by remaining in a state of discharge for extended periods.)
If someone cannot afford to top up their prepayment meter then they could be at risk and the risk will be elevated because they are more likely to use candles.

On the other hand the likelihood of this will be fairly low because people are likely to make electricity use a priority for all manner of other reasons- phones etc. For those who really cannot afford this they probably will be well known to the Landlord as they will be on housing benefit. As I said the Landlord knows their tenants and their behaviour.

If we cannot use a BS as a benchmark standard then its a poor show.This one has been around a long time and so have pre-payment meters. You probably remember putting a shilling in the slot as I do. There are also risks in rewiring to feed detectors from the Landlords supply. Apart from the issues under BS 7671  and giving it away with a sign there is a possibility that the smoke detector will be unplugged and a feed taken from the Landlords supply for other purposes. I have seen similar diversions of the landlords supply many times over the years usually creating a much more significant fire risk through overloading and improvisiation.

[Midland Retty]

It is a well known issue.

Lyle are you referring to the fact that BS 7671 states that smoke / heat alarms can no longer be powered from a lighting circuit? Is that specifically what you mean about introducing problems complying with BS7671 2008 and it generally being an undesireable situation from an electrical safety perspective?

[lyledunn]

Midland fire,
 What I am referring to is the requirement to have double pole isolation at the installation origin in domestic premises. The implication in this requirement is based on the fact that safe systems of work such as safe isolation would obviously be less likely than in a work environment.
Kurnal has neatly summarised many of the concerns. It is my instinct that despite any fire safety concerns relating to security of supply, it is less than a tolerable risk to have 230v detectors fed from the landlords supply, whether or not an isolator is supplied on the circuit.
With respect to smoke detectors on a separate circuit, 560.7.1 requires safety circuits to be independent of other circuits. Simple statement but I bet they were not thinking of domestic smoke alarms!
I would not like to be thought of as churlish but Colins response is to say the least surprising. How come card meters were thought about for Grades A,B and C but not thought about for grade D? As Kurnal points out, like many, I am very reliant on BSs as reference points for good design, construction and verification.
Might I be so bold as to ask Colin; if it wasn't thought about in  the formulation of the Standard, have you thought about it since and would you like to proffer even your own perspective on the subject?

[John Webb]

The other problem regarding the use of a Landlord's supply for smoke detectors is that such a supply might be on a different phase to the tenant's supply. BS7671 requires a minimum separation between phases and/or appropriate notices. With light fittings and detectors likely to be in close proximity on a ceiling, the two phases could cause difficulty in complying with BS 7671 requirements.

[kurnal]

There could be simple solutions if we could change the technology. But with 4 million homes already fitted with pre payment meters (it would be interesting to know how many of these have smoke detectors) retrofitting new technology is not going to happen.

Smoke alarms are only mains powered because that was a convenient and reliable source of supply. If it is no longer considered appropriate then alternatives need to be found. The detector  only needs 9 volts so an independent SELV feed of this nature could be provided either direct from the mains intake or on a central system in flats.  

However, this would require a complete redesign of the current range of alarms for Grade D systems and in my view is unlikely to happen. Certainly not retrospectively and I would suggest that the market is effectively saturated- all existing homes likely to be fitted with pre payment meters will already be so fitted.

Perhaps the current initiative by MP Adrian Sanders - The Fire Safety (Protection of Tenants) Bill - if it takes off- could encompass this?

http://www.thisisderbyshire.co.uk/Smoke-alarms-rented-homes-law-thanks-MP-campaign/story-11604704-detail/story.html


It would be easier and cheaper for the fire service to obtain a list of all premises in their area with pre payment meters from the utility providers and to install long life battery Grade F smoke alarms to supplement the mains powered ones if this is really an intolerable problem.

[Clevelandfire 3]

Sorry but can you confirm what premises you are talking about please because you seem to have gone off at a tangent. Are you talking about single domestic dwellings or hmos or what. If you are talking hmos then what lyle has said is quite true. Most installs dont comply with 7671. But then again that isnt to say that they have to. Anything pre 2008 is fair game until them come to replace or upgrade. So lets just slow down a bit and make the position clear about the type and age of premises we are talking about.

[colin todd]

Kurnal, because it was not considered tolerable, it does not mean that it was considered intolerable either. You must learn to read things before you hit that reply button and go off on one of your rants. I said it was NOT CONSIDERED -as in CONSIDERED AT ALL.

The concern about Grade A, as Cleveland is trying to tell you, is that it will be used in HMOs, where clearly it is totally unacceptable to run a landlord system off a pre-payment meter. As I keep trying to tell you, this has been a well known issue for EHOs for, to my certain knowledge, more than 10 years ago, when it first began to raise its head.

With regard to dwellings, we DID consider, the issue of pre-payment meters, in defining the minimum standby duration.  More specifically, we were concerned to know whether capacitors were ok, given that they cannot last anything like as long as standby batteries. Rather than rush off with opinions based, I acknowledge, with lots of good intent but no research or analysis, as I so often read here, we held discussions with social researchers to find out about patterns of pre-payment meter use by low income vulnerable groups.  That is how we came by 72 hours, which is achievable with capacitors. Batteries will last way way longer, but long income families often use pre-payment meters in a manner known to social scientists as cycling, whereby they intentionally let meters run out at certain times, and then use them again when they want the electricity. We were advised that 72 hours would be adequate duration and a benefit of capacitors that trades off against their much much shorter standby time is that they recharge quite quickly. 

The commentary in BS 5839-6 kind of explains this.  You will also find pages of explanation in my text book on domestic fire detection and BS 5839-6, which I will gladly supply to you at author's discount so that you dont need to lie awake worrying about it. It refers to the research we did and the fact that anyone suffering disconnections for longer periods lie right at the tail of the statistical distribution, but if they are an issue, you make sure that the smoke alarm has a standby battery rather than a bank of capacitors, which will nearly always be the case anyway.

After that, we never considered the issue and did not revisit in when we had to address Grade A. It does not mean that there is a problem, nor that there is a need for people to go buying additional battery operated devices. It is just that the concern realted to HMOs and pre-payment meters-hence the attnetion was focussed on Grade A.

(By the way smoke alarms are not SELV, so you need to revisit your electrical engineering CPD.)

[kurnal]

Thanks Colin. My "rant" as you describe it was actually penned in a good humoured style or thats how I felt.
(Rant-  To speak or write in an angry or violent manner).

Anyway thanks for the full picture. (Which I feel you might otherwise not have shared with us?) 

I, perhaps wrongly, jumped to the conclusion that Lyle was referring to social housing comprising dwellinghouses of purpose built flats. I assumed this because the question would not have arisen in any premsies in which a Category A-C system is installed because BS 5839-6 is absolutely specific that the supply must not be derived from the consumer side of a pre payment meter. So sorry Cleveland, I should have spelled out more clearly what I was going on about.

OK I did drift into cloud cuckoo land in suggesting  that if it was a problem a redesign of detectors operate at 9v rather than 240v and to be fed from a central 9v landlords communal power supply system (which I believe if it were created would have to be a SELV system) But I dont pretend to be an electrical engineer and will always defer to those with greater knowledge.

So Lyle I interpret the word of the oracle to be that provided the Grade D alarms have a battery back up rather than capacitor there is no need to be concerned. No doubt if I have misread that I will be corrected

(thinks I wonder if the gradual deterioration of battery capacity with age was taken into account?)

 

[colin todd]

They deteriorate slower than retired firemen, who have much less capacity of value than standby batteries.

[colin todd]

As always, Big Al, you are close.  You do not need to worry about batteries or capacitors or anything else, other than, for this evening at any rate, what Mrs Kurnatowski is going to give you for supper tonight.  In exceptionally rare cases, you might want to ensure that there is plenty of capacity in the standby supply, but almost without exception there will be, so I would be more worried about the effect of BS 9991 on domestic fire safety. BS 5839-6 is fine and will be getting even better before too long. It has always been in safe hands, so sleep well tonight and dream of the days when there were beds in Matlock Bath fire station.