Smoke alarms in VERY big house

[kingeri]

Guy I know has bought an extremely big house, 8 bedrooms, 5 bathrooms, 4 garages etc etc. He asked me to do an EICR, which I did just before Christmas, no issues to report. He's asked me to fit smoke alarms throughout the property, and he's insistent on wired. So, I've been thinking about the best way to do it. On a normal property, simple enough, just run run t&e from lighting circuit to first alarm, then 3c&e between that and the others. My consideration here is that it would be a massively long cable run from a lighting circuit (v drop). So, do I do this anyway but just use bigger cable? Or would it be better to install a separate circuit? Or.....now bear with me on this one cos it's a bit whacky....use the local lighting circuits to power each alarm and just run single core & earth between the alarms for the control. Not sure if that would actually work or if it's otherwise a good idea. Thoughts?

 

[Willbowling]

Well as long as he doesn't have a three phase supply in this mansion then why would it not work? Seems like the sensible solution to me.

 

[Andy78]

Why not take power to each device from local lighting and have them wirelessly interlinked ? Sounds like it would be a lot easier in a house that size. You can place boosters for areas of weak signal.

 

[telectrix]

as above. & check with client that he's not wanting wired interconnections, but just wants mains powered detectors.

 

[loop3]

Geez, be careful here. Firstly locally power alarms ( each alarm to closest light) connected by radio link are ok on te. Independent alarm circuit = fp cable. Very big houses, centralised alarm system that has zones. Don't get done.

 

[TAZ]

AICO do a very handy book called the ELECTRICAL CONTRACTORS HANDYBOOK 2ND EDITION. if YOU CONTACT AICO they will pop one in the post to you. It gives all the different scenarios that you normally come across & gives the minimum requirements as to the different grades needed in different types of properties . Well worth looking into & it was FOC at the time Most domestic alarms are hard wired in smaller domestic properties & this little book gives a maximum cable length of 250 m. Most domestic smoke alarms would be wired in 1mm or 1.5 3 core + E The volt drop would be incredibly small & the current drawn would be minimal A circuit of this length best practice would dictate a separate circuit, together with any calculations on cables that are used

 

[loop3]

With fire alarms. Or any electricals. Never let the customer dictate the arrangement.

 

[wade88]

Was going to say, surely the voltage drop wouldn't be sufficient to negatively effect the operation? Separate circuit for me.

 

[TAZ]

A house this size would probably need a grade A or grade B with a central control panel. The number of stories & floor area can also dictate as to the type of alarm that is required & the type of category needed.

 

[kingeri]

Thanks guys. I have the Aico book already, will dig it out. The guy is adamant he doesn't want wireless, but once I show him how much disruption I will cause running cables in, he might well be convinced to change his mind.

 

[Welchyboy]

You will need at least a grade B system to comply with BS5839 pt 6

Normal mains interlinked smoke would not comply for a large house like this

 

[wade88]

Well thats exactly the thing isnt it. Disruption over practicality. I had the biggest drama with a bloke over a door bell. £35 for wireless system, door bell functions perfectly, change batteries every 48 months (being a little facetious) or commit unwanted time and money on his behalf, for me to put in a wired one, at significant extra cost and destruction, er i mean disruption.

Either way, doesn't matter to us, the bill simply goes up for all extra work, but doesn't half annoy me when your just trying to save someone some money over trivial things, and they just watch the horns on your head grow.

 

[smuggler]

if the any floor area is over 2000sq ft you need a fire alarm with panel worth checking it out

 

[tazz]

If this is a private domestic property, which has not altered under building control nor is being used as HMO then the customer can have what he wants, even a grade F battery alarm...its his property. If its under alteration, or HMO then this would be under Grade A (full control panel etc.) under BS5839 part 6 as it is over 3 levels, and building regs 2000m Sq

 

[TAZ]

I think it is difficult to give an accurate answer as to what the exact requirements are as not enough details are available. The way i am looking at it it states customer wants alarms fitted throughout ie everywhere a fire could start & not just in the circulation areas. LD1. If a standard mains / battery system were to be installed & i am assuming this is a PRIVATE dwelling & not rented out or an HMO The installation of such work would be notifiable & a fire alarm certificate together with an electrical installation certificate( new circuit) would be required this then would not be in compliance if a grade A or B alarm is is the minimum cover for that size of dwelling Your thoughts folks