Regulation of Low Load / Low Voltage Electrical Connections

[Ferdinand]

Not quite sure  to address this, so I will just ask this question about connections such as hard wired fire alarms and PIV fans (typical load 10W) etc 

 

Now, there is no issue with us doing those on our own home, provided we do it right. Or having an electrician do the same.

 

I am interested as a landlord. The big issues (obviously) are the linked ones of tenant safety and potential liability, with cost getting a look in once appropriate standards are met. 

 

My practice in a full rewiring would be to get the electrician to do hardwired alarms then it is certified with the rest under the 5 year inspection. In a non-wiring small refurb or existing house I currently use 5 or 10 year sealed battery alarms to avoid the ‘tenant not replacing battery’ safety issue. I need to check current regulations before I do the next one.

 

My questions ... probably for tradesmen mainly, are:

 

1 - How are low power connections regulated? Is it Ok for a non Competent Person to connect up a PIV fan to say the lighting power wires? is it OK if the connection is to a Competent Person pre-installed Connection unit in the loft? The latter would save a second visit by the Electrician.

 

2 - What about fire alarms?

 

3 - What about 12v fire alarms? IIRC 12v is not regulated.

 

4 - Is there a significantly different fire hazard from using 12v vs 240v wiring for eg fire alarms?

 

5 - Does this mean that running a stepped down to12v circuit into the loft space is a good idea?

 

6 - Are there many pros or cons to using 12v lighting?

 

Thanks for any replies

 

Ferdinand

 

 

[PeterW]

Most fire stuff isn’t 12v it’s 24v for Sounders / Panels / Detectors etc and should be installed by a qualified engineer. I wouldn’t let anyone untrained anywhere near it, LV or not as it’s safety critical. 

[Jeremy Harris]

In general, there isn't a requirement for a competent person to do any work on an electrical circuit that operates at ELV (or SELV), which is one with a voltage below 50VAC or 75 VAC (under the LV Directive) or 120 VDC (under BS7671).  SELV has lower voltage limits so is covered by the ELV rules.

 

Having said that, there is still a requirement that any ELV or SELV circuit is safe and functional, particularly in the case of a fire or smoke alarm, as the functionality of those comes under fire safety regulations, rather than wiring regulations.  As such, I'm not sure I would be comfortable, as a landlord, allowing tenants to do any work on such systems.

 

ELV lighting is less of a concern, but there are still fire risks associated with the installation, so although the regs may not require a competent person to do the work, again I think I'd be concerned, were I a landlord, that a tenant could screw up.  One easy error to make would be for a tenant to replace something like a 12 V LED MR16 lamp with a 12 V halogen lamp, that then overloads the capacity of the ELV cable supplying the fitting.  In an ideal world the transformer running ELV lights would shut down and protect the wiring, but I bet there are a lot of older 12 V downlighter installations that have re-used the original halogen rated transformers, and some may well have had the original heavy gauge wire replaced with something lighter (and cheaper) on the basis that LEDs were being used.

[epsilonGreedy]

22 minutes ago, Ferdinand said:

6 - Are there many pros or cons to using 12v lighting?

 

 

I started a thread asking why whole-house 12v lighting did not feature in this forum of otherwise progressive thinkers. The answer is partly due to mechanical light switch contacts getting frazzled by the sparkyness inherent when completing a dc circuit. I wish I had titled my thread "Whole house dc lighting" because my original thread got side tracked over whether 12v was the best choice for dc lighting when in fact my main interest was central rectification ac to dc.

 

 

Edited June 18, 2018 by epsilonGreedy

[ProDave]

A number of issues.

 

The rules are different in Scotland and require hard wired mains powered smoke alarms. That requirement may come to England in the future.

 

The electrical regs are all about voltage not power. A 240V smoke alarm comes under the same regs as a 10KW heater.

 

England and Wales has Part P which imposes restrictions on who may do certain wiring e.g new circuits, or circuits in bathrooms. Scotland and NI does not have this.

[newhome]

3 minutes ago, ProDave said:

The rules are different in Scotland and require hard wired mains powered smoke alarms.

 

QQ on this if I may please. When the battery knackers you have to replace the whole unit? And if you can’t source exactly the same one you have to replace every smoke alarm? At least that’s what I was told by the sparks and I had to pay for all 5 to be replaced when the battery went in one (after 7 years). 

 

 

 

[Jeremy Harris]

Depends.  Our mains powered and linked smoke/fire alarms have a lithium PP3 back up battery, that should last around 5 to 8 years.  It looks easy enough to replace, pretty much the same as replacing an ordinary smoke alarm battery. 

 

 

[ProDave]

3 minutes ago, newhome said:

 

QQ on this if I may please. When the battery knackers you have to replace the whole unit? And if you can’t source exactly the same one you have to replace every smoke alarm? At least that’s what I was told by the sparks and I had to pay for all 5 to be replaced when the battery went in one (after 7 years). 

 

 

 

Buy a decent make like AICO. They are not that expensive if you search on line, and there is no issue replacing a failed or time expired unit.

 

Apart from anything else, AICO are one of only a few with decent back plates and decent electrical terminations.

[Jeremy Harris]

Pretty sure I have a spare brand new AICO smoke alarm, as I made an error when buying them and bought two smoke alarms instead of one heat alarm and one smoke alarm.  The box has been opened, as I only discovered the mistake after installation, but as all the AICO units use the same backplate it was easy to just swap the smoke one out for a heat one.

[Ian]

32 minutes ago, ProDave said:

The rules are different in Scotland and require hard wired mains powered smoke alarms. That requirement may come to England in the future.

The English Regs Part B Vol 1 also say that smoke alarms must be mains powered.

[newhome]

26 minutes ago, ProDave said:

Buy a decent make like AICO. They are not that expensive if you search on line, and there is no issue replacing a failed or time expired unit.

 

 

Thanks. I could find a replacement one online, but they didn’t want to fit it. Can’t remember what make it was now. They supplied and fitted all new ones. I will have to check what make they are. I will have to get a spark in to swap it over when the next one goes anyway as I wouldn’t fiddle around with mains stuff. 

[Jeremy Harris]

I deliberately chose the mains powered AICO ones that use a PP3 backup battery, as when the backup battery needs replacing you don't need to replace the whole alarm unit, just the battery, and this can be done as easily as changing the battery in a non-mains powered alarm. 

 

I believe the ones with the hard wired back up battery are designed for use in rented or social housing, where there's an anti-tamper requirement.  They all wire up the same way, as far as power and the inter-alarm interconnect is concerned, so should be a quick and easy thing to change.

[newhome]

1 minute ago, JSHarris said:

 

I deliberately chose the mains powered AICO ones that use a PP3 backup battery, as when the backup battery needs replacing you don't need to replace the whole alarm unit, just the battery, and this can be done as easily as changing the battery in a non-mains powered alarm. 

 

I believe the ones with the hard wired back up battery are designed for use in rented or social housing, where there's an anti-tamper requirement.  They all wire up the same way, as far as power and the inter-alarm interconnect is concerned, so should be a quick and easy thing to change.

 

 

That sounds much more sensible. I hope I’ve got those now. TBH when the first one went outside the bedroom in the middle of the night (and it was loud!) I thought I could just remove the battery but no, desperate times trying to rip it out at 3am lol. 

[newhome]

36 minutes ago, newhome said:

They supplied and fitted all new ones. I will have to check what make they are.

 

Firex are the ones they fitted. 

[ProDave]

10 minutes ago, newhome said:

 

Firex are the ones they fitted. 

Your electrician is going down in my estimation. Old stock, discontinued in 2009 https://www.kidde.com/home-safety/en/us/about/firex/

[newhome]

1 minute ago, ProDave said:

Your electrician is going down in my estimation. Old stock, discontinued in 2009 https://www.kidde.com/home-safety/en/us/about/firex/

 

Well that doesn't surprise me after they shoved in that MCB instead of the proper thing (that's still wrong as it happens). When I looked up what I had and tried to buy a replacement one it was dearer than what they wanted to fit. Guess they had some of the Firex ones lying round somewhere redundant. Nothing surprises me now TBH. I guess I can expect them to fail pretty quickly then . 

 

[ProDave]

 

They should have a maunfacturing date somewhere. That site does not say WHEN the Firex brand was discontinued, just that Kidde took over he brand in 2009 and it is now discontinued, so it might have only been last year that they were discontinued and they might still have been current?

[Jeremy Harris]

For info, these are the AICO units I used: https://www.tlc-direct.co.uk/Manufacturers/Aico/Smoke_Alarms_Mains_Alkaline/index.html

 

Not expensive, and dead easy to unclip from the base to change the backup battery.  You can also use a lithium PP3 backup battery, rather than an alkaline one, that increases the battery shelf life a fair bit.

[newhome]

Yet another occasion where BuildHub would have come in handy. Hey ho! 

[Guest Alphonsox]

For some reason there always seems to be a lot of AICO kit on ebay - I got most of my stuff from there.

[Ferdinand]

There's a whole bundle of questions here :-). This may take a post or two.

 

The post was prompted by my spotting of 12v fire alarm systems from the likes of TLC.

 

Firstly, I am talking about single family rentals, or possibly "small HMOs" (ie sharing like a family or up to I think 3-4 people, though in Scotland  I think 2 singles sharing is officially an HMO) rather than large or 3 storey HMOs where control panels and emergency lights and things come into [;ay.

Secondly, I don't think that Ts doing work applies in my consideration - apart from removal of batteries if the alarm keeps going off or for use elsewhere. One reason for sealed units rather than expecting the T to replace a battery every year. Clearly the only formal legal requirement that can be laid on an LL is at the start of the tenancy, since after that point the LL has no absolute right of access, never mind being in loco parentis to supervise tenant behaviour.

 

Thirdly, I think that lights becoming something of a non-issue, as with LEDs they will hardly ever be replaced and a whole series of short tenancies may go through with no bulb expiries. At home I replace more than 55 GU10s with LEDs back in about 2014, and I think only 1 or perhaps 2 have popped since then.

 

Fourthly, as an example in the Little Brown Bungalow renovation I fitted all mains powered interlinked AICO in every room (except possibly the CO detector), and the lecky put a fused connection unit or two in the loft, one of which my maintenance guy later used to install a PIV ventilation unit. I recall the Fire Alarm bill being a bit of a shock, and a surprisingly large part pf the reewiring expenditure. I think that technically we did not require Building Regs involvement, as that was done by the Competent Person electrician who did all the alarms. My only 'noncompliance' (though not a formal requirement aiui even in a rental) *may* have been the PIV unit - would have to check the certificate.

 

Specific replies following.

 

Ferdinand

Edited June 18, 2018 by Ferdinand

[Temp]

Looks like rules on smoke alarms in Scotland are changing or have changed post Grenfell....

 

https://www.bbc.co.uk/news/uk-scotland-43443725

 

In practical terms, the law will require private homes to;

• have at least one smoke alarm installed in the room most frequently used
• have at least one smoke alarm in spaces such as hallways and landings
• have at least one heat alarm in every kitchen
• have a carbon monoxide detector

In addition, there will be a 10-year age limit for alarms and all alarms will have to be ceiling-mounted, and should be interlinked.

 

 

 

 

 

[newhome]

1 minute ago, Temp said:

have a carbon monoxide detector

 

Why would everyone need one of those? Aren't they for gas or solid fuel? I don't have one here (electric heating). 

[Jeremy Harris]

8 minutes ago, newhome said:

 

Why would everyone need one of those? Aren't they for gas or solid fuel? I don't have one here (electric heating). 

 

It makes no sense at all to have a CO detector in a house that has no combustion devices, as that's the only source of CO in a house.  Makes more sense to have a CO₂ sensor, as that's a pretty good indicator of general air quality indoors, I've found. 

 

When I measured CO₂ levels in our old house I found an explanation as to why our bedroom always seemed to feel stuffy, despite a small window always being open.  The CO₂ level was increasing to around 1,600 ppm in the early hours of the morning, only dropping when we got up and opened the bedroom door.  Opening the door quickly dropped the CO₂ concentration, as it allowed through ventilation.  I've no doubt that window ventilators would be just as useless as leaving a small window open, as long as the door is closed.  It probably explains why houses with MVHR always seem to feel much fresher.

[newhome]

51 minutes ago, JSHarris said:

It makes no sense at all to have a CO detector in a house that has no combustion devices, as that's the only source of CO in a house.  Makes more sense to have a CO₂ sensor, as that's a pretty good indicator of general air quality indoors, I've found. 

 

Just had a look.  CO detectors / alarms are peanuts, but CO₂ sensors seem quite expensive in comparison. I don't think I really need one here tbh as I never notice it being stuffy. especially with only me here plus there is MVHR.