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Thread: Retrofitting Idratek in soon to be our house

  1. #11
    Moderator Gumby's Avatar
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    Quote Originally Posted by Geps View Post
    EDIT: To be pedantic.....I'm also 90% sure the low voltage wiring for the Idranet in the pdf Paul posted is also now forbidden as it is outside deemed safe zones and so doesn't have the metallic, earthed, protection covering it that cables chased at that depth require. Would hate to see someone wire there house up that way and then have the BCO come round and request it is changed.
    This one is somewhat contentious. I have always interpreted the building regs as identifying "safe" zones for wiring not just from the aspect of avoiding injury if someone were to hammer a nail into mains wiring, but also from the aspect of avoiding damage to any wiring, even where there is no shock hazard. It would be deeply inconvenient to damage your control wiring. So I personally feel that all control cables should be run in safe zones. This creates it's own challenges in terms of preserving isolation form the mains, especially in the back box and also recommended separation distances from mains cables.

    It is one reason why using mains rated insulated CAT5 is helpful. If you separate the low voltage and mains in separate sleeving or conduit then you could provide insulating sleeving to get round the back box issue.

    Whether you _have_ to provide metallic earthed conduit to buried low voltage cables (with no shock hazard) under the building regs I am not sure, but I can certainly see the case of mechanical protection.

    The best thing you can do is use a very genn'ed up sparky who has some experience with wired home automation systems or at least is prepared to discuss what is do-able without too much sucking of the teeth.

    You should rely on professional advice and not what we have written on the InterWebs.
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  2. #12
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    My final suggestion...

    In a retrofit situation I would consider using an SRH and a single outlet. You can spur this from an existing double socket provided it is on the ring main and it can be done with two single pattresses. The single outlet is limited to 10A, but few household items need this kind of power. Safe zones can work nicely here, since you will wire the mains cabling horizontally from the existing double and can drop the low voltage control cable vertically in the "new"safe zones inline with the Idratek module pattress.

    Remember that you don't want to be changing your control scheme in Cortex all the time, so your controlled socket is likely to be used for fairly static equipment. This approach works well to give controlled outlets for table lamps and the like, and can also be used for powering down equipment with poor or non-existent standby modes, possibly ganging them all up on a power strip.

    For example, I reviewed my TV/Hifi cabinet standby power draw and found all the modern stuff had negligible standby draw, certain items like PVR/Sky that needed power all the time, so might as well be in the standard uncontrolled socket and then just one or two items with noticeable standby power that I could usefully control. So a single controlled socket was adequate in that position.

    If you have lots of heavy current loads, like heaters or things with heaters in them then you might want to review your ring main design anyway.
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  3. #13
    Moderator Gumby's Avatar
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    Did I say finally? I lied

    Quote Originally Posted by eddr View Post

    Also, I have noticed in our soon to be house that theres a light downstairs by the front door, and a light at the top of the stairs. The light at the top of the stairs has a dimmer switch at the top of the stairs, but downstairs has a normal switch which is a double (one switch turns the light by the front door on and off, the other the light at the top). How would I go about changing the light at the top of the stairs to be Idratek controlled whilst also having the light at the bottom also controlled?
    We were having so much fun discussing SRHs and DRHs I don't think the lighting question got answered.

    So I'm guessing that the dimmer controlled light is wired to be "2-way" controlled, that is, you can turn it on and off both at the switch at the bottom and at the dimmer at the top (probably by depressing the dimmer knob).

    The first thing is to understand how 2-way light switches work (time for a bit of ASCII art):

    Code:
                      o---------------------o
    Live -------o                               o--------- BULB ------- Neutral 
                    \ o---------------------o/                        
    
                    SW1                      SW2
    With two way switching both switches are two-way and there are actually two current paths to the bulb (top and bottom in the diagram - usually in a 3core+earth cable). If both switches are up, or both switches are down, current will flow, bulb on etc. If switches are differnt, current can't flow, bulb stays off.

    With IDRATEK control, you don't need this, a single relay unit switches power to the bulb and multiway switching is done by communications over the control wiring as configured by Cortex. This can be done with Reflex as well, so your fallbacks can continue to operate as multiway. This makes multiway switching much easier to wire for, since you don't need the mains wiring between all switch positions.

    Therefore, you could replace the top switch with an SLD dimmer module and the bottom switch with a DRB. Only one relay of the DRB is used, to switch power to the bottom light. The second button on the DRB can be configured to toggle the light connected to the dimmer by controlling the dimmer. The SLD buttons can be configured to control the dim level in up/down fashion, or, in fact, can be reassigned to do something else. So you could have one button cycle dim level up and down and use the other button to do 2-way switching to the downstairs light.

    Since you are a retrofit, you would need to check where the wiring for the 2 way actually goes, since the load and live feed can be at either end. At worst youd need to use the existing 2-way cable between positions to carry the live to the dimmer ie a terminal block in the back box to join stuff up.

    Of course, the whole delight of having properly automated lighting is that you don't need to touch the light switches much...
    Last edited by Gumby; 23rd March 2011 at 12:41 AM. Reason: pressed the wrong key
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  4. #14
    Automated Home Guru Geps's Avatar
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    Quote Originally Posted by Gumby View Post
    AIUI technically the IEE Regs are not law. The building regs do have legal force and following the IEE regs is one way of meeting building regs.
    It's an valid point because technically yes, but the IEE regs are deemed to be safe, good practice which is the legal requirement....so to do something different from what they specify would place the burden on you to prove it's safe as I see it.

    If your argument held you couldn't fit a 5A fuse in a power strip.
    Not at all, I'm saying the illegal aspect is providing a circuit which can't handle the potential load from the socket (13A) and then lowering the values of circuit protection to suit. In that example, you have something that can handle the load and just changing the circuit protection.

    A hypothetical is that you're away for a businesss trip, SWMBO is at load and (without wanting to sound ***ist ) is vacuuming. The vacuum gets blocked and draws alittle extra current which pops the 10A fuse. She calls an electrician who has no reason to believe the circuit can't handle 13A and puts in a 13A fuse.

    You have round pin connectors for 5A circuits for example.


    AS for the safe zone comments, I'm not sure it's that difficult.....if you run wires from beneath the floor to under the pattress you meet the safe zone requirements and obtain 200mm+ separation whilst also saving on cable as the drops from the pattress to the floor are shorter than the ceiling


    earthed conduit to buried low voltage cables (with no shock hazard) under the building regs I am not sure
    Again to be really pedantic, it's actually extra low voltage. 230V is classed as low voltage and so if you ask that question to an electrician, they could think you're talking about mains.


    I'm starting to reach the point of installing the sockets on my Idratek install and I'm sure there must be an easier way to install it. The of doubling up sockets with FCU and Idratek modules doesn't appeal. If I find a method to save on just one I'll be sure to report back.

  5. #15
    Automated Home Sr Member eddr's Avatar
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    Uh oh what have I started!

    Well thank you both for all your feedback, things making alot more sense now...

    So it looks like really my only options:

    To leave uncontrolled 'twin' sockets and run a spur with a single controlled socket which would have to be clearly marked so nobody plugged a heater/hoover into it or risk blowing the 10amp fuse!!

    OR

    Have another two boxes next to the twin sockets (which would become singles) - This means four boxes per two sockets.... I'm drawn to the option above really, but controlling all sockets would be ideal.... hmmm


    As for the lighting, that sounds great - Would I have to somehow turn one of the two way switches into one way then, and put a dimmer socket where the redundant one (dead) would be?

  6. #16
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    Default Ring mains and automation

    Well seeing as I am also about to retrofit idratek into an old solid walled house (as well as a nice easy extension) I thought I would add my 2p, like all good bystanders I'll change the question a bit to muddy the waters. The short answer is um don't do it. As has been said most 13A wall sockets either power temporary things liker vacuum cleaners or permanent things like hifis or clock radios, neither of which are usefully turned on and off remotely. If they have poor standby ratings replace them it will be cheaper than the rewire anyway.

    So far in my plan the only things I want to switch from a sockets are lights and all of these can easily be done via a single round pin plug. Ring mains also tend to be noisy and are now basically considered a bad idea in the new IEE regs anyway. If the sparky is tearing up your walls I would suggest you ask him to look into breaking the ring main and creating several spurs. Not always as hard as you think once the floor boards are up.

    Another even simpler option is rf sockets (I plan to reuse some homeeasy sockets and control them from an HAH hub). I might even tie in some Idratek DIO to allow reflex control.

    Al tough I have just had an idea: what about a fused spur with flex? As far as I know this is still allowed and would be compliant as long as fuse rating is clearly marked externally. Of course your device would be made permanent but surely it would be anyway if you have gone to the trouble of automating it?

    Just a thought

    Simon

  7. #17
    Moderator Gumby's Avatar
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    Quote Originally Posted by Geps View Post
    It's an valid point because technically yes, but the IEE regs are deemed to be safe, good practice which is the legal requirement....so to do something different from what they specify would place the burden on you to prove it's safe as I see it.
    Exactly. And it's going to be harder to find a sparky that will deviate from the IEE regs, partly because for insurance reasons. However, I made this point because the IEE regs can't cover all conditions and tend to lag technology (there is very little consideration of control and telecomms in IEE regs), so there is a potential to handle things differently.

    There are some sparkies around who have specialised in HA installs. Also, it's worth discussing any plans with BCO before you start to discover their attitude to it all, their approach can differ significantly because HA is still a very uncommon installation. And in a retrofit BCO may not be involved if the sparky is signing off the works.
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  8. #18
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    Quote Originally Posted by Geps View Post
    Not at all, I'm saying the illegal aspect is providing a circuit which can't handle the potential load from the socket (13A) and then lowering the values of circuit protection to suit. In that example, you have something that can handle the load and just changing the circuit protection.

    A hypothetical is that you're away for a businesss trip, SWMBO is at load and (without wanting to sound ***ist ) is vacuuming. The vacuum gets blocked and draws alittle extra current which pops the 10A fuse. She calls an electrician who has no reason to believe the circuit can't handle 13A and puts in a 13A fuse.
    I think you are reading too much into it. I've never found anything in the regs that says the circuit and protection behind a 13A socket has to be rated at >13A. It might be an inconvenient practice for the reasons you have identified, but I don't believe it is illegal, especially if the socket is labelled correctly. 5A and 3A round pin plugs are not usually fused, so it's not as simple as saying they indicate lower current.

    The principle of the regulations is that the circuit has to be capable of handling at least the fault current limited by the nearest upstream protective device.

    In your hypothetical case I think the SRH fusing is sufficiently unusual for the sparky to think something different is going on. And, since the Building Regs require adequate documentation of modifications they could then refer to the documentation.
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  9. #19
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    Quote Originally Posted by Geps View Post
    Again to be really pedantic, it's actually extra low voltage. 230V is classed as low voltage and so if you ask that question to an electrician, they could think you're talking about mains.
    Agreed, that's really pedantic; especially as I was echoing previous colloquial use.

    It is certainly worth pointing out to a sparky or BCO that the nominal supply is 12V, I think it's usually set a bit higher at 13.8V on the big power units to allow for a bit of volt drop.

    And an interesting and related question is whether an Idratek installation is SELV, PELV or FELV, since that can have a bearing on what is permitted under the regs. Sorry, I meant under BS 7671.
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  10. #20
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    Quote Originally Posted by Geps View Post
    AS for the safe zone comments, I'm not sure it's that difficult.....if you run wires from beneath the floor to under the pattress you meet the safe zone requirements and obtain 200mm+ separation whilst also saving on cable as the drops from the pattress to the floor are shorter than the ceiling
    As long as you don't have solid floors.

    It's is true that if you run mains and Idratek control into different sides of the back box it works out very nicely. That is why SRH's next to existing doubles are convenient. Mains comes in sideways, Idratek from top or bottom. Bottom is better since it can come straight into the Idratek insulation box.

    If you are chasing walls then you can run mains and Idratek side by side in a vertical drop into the typical two holes in the top (bottom) of a single pattress, separately sheath them and the only point you have to think about is the short distance where the Cat-5 shares the back box with mains.
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