I'm planning to install some outside lighting on a soon-to-be new patio area, and some other places in the garden. There will be a mix of mains voltage post lights, and some low voltage stuff too. I wish to use LD11 X10 dimmer modules to control the lights, and was thinking that the most convenient place to put these would be in an standard hinged door steel IP66 enclosure outside (in a fairly sheltered location, in a corner). Cabling to the mains lights would be 1.5mm2 SWA, and I would like to keep the LV transformers within the same enclosure.
Just wondered if there's any fundamental reason why this setup wouldn't meet regs in a domestic installation (assuming the actual wiring itself is all safe and correct etc)?
Sounds OK to me. I have an LD11 indoors in a Consumer Unit case. It takes up 4 ways, and I have a B3 MCB next to it on the basis that it might help protect the triac if a lamp flashes over at moment of filament burnout, it's faster than the built-in fuse, and it's dirt cheap compared with replacing the LD11 (although LD11's have come down in price since I bought mine). The LD11 is a nice item, with gradual dim up and down on both the manual switch and X10 control. I do not have anything which can send the "extended" X10 commands, so I don't use that feature of it.
Watchout for heat dissipation. The LD11 doesn't generate much noticable background heat, but the triac will necessarily generate something like 1W heat per 200W of load. The LV transformers will also generate heat. Allow for this when choosing a box, and don't go for the smallest size with everything crammed in tightly. If you are using multiple LD11's, I would suggest leaving one way spare between them (or occupied by MCB which generates negligable heat at low currents). You could also include a thermostat in the box set to, say, 40C to cut the power to the box if it does get too hot.
Also, you'll need to do some checks on the earth fault loop impedance and voltage drop on your 1.5mm² cable. This shouldn't be an issue if protected at 6A unless it's very long (sorry don't have the OSG on me to look up max length). If the LV runs are of any appreciable length, they will need to be thicker cable to avoid significant voltage loss.
An outdoor cabinet containing electronics is going to need some protection against internal condensation. Typically this is provided by a combination of ventilation, spacing the electronics away from the sides where condensation forms/runs, protected from drips from internal top surface, drain holes so the condensation which forms can escape, and possibly provision of a low power anti- condensation heater.
IP66 is probably OTT, and difficult to meet the anti-condensation issues. You could probably go down as low as IP34, unless you plan on directing firehoses at it.
OK well I've had no objections, so I guess it sounds OK! My next question would be, what would be the preferred method of mains supply to this setup, given that I have a few options:
1) Run feed from existing internal lighting circuit (non-RCD protected)
2) Run new feed from CU on RCD-protected side
3) Run new feed from CU on non RCD-protected side but fit an RCBO
4) Run feed from existing internal lighting circuit and include a separate RCD in the IP66 box
AIUI an RCD is not be mandatory, but might be a good idea? Im thinking option 4 might be best.
Thanks Andrew, didn't see your post until just now. I had been planning to use something like this:
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I already have one left over from another project. I hadn't considered the condensation issue, so maybe I should look for a different type of enclosure...?
It sounds close to best practice to me, provided any ventilation requirements are met. The dimmer units can run quite hot.
No. I would not share outdoor circuits with RCDed indoor circuits.
Good.
An RCD is a good idea, provided that the lights aren't safety critical. Not essential, though, unless the house is TT earthed. I'd use a 100mA one, though, to avoid nuisance trips, unless the circuit is dual purpose and supplies sockets etc.
Nothing that a drill and hacksaw couldn't sort out!
I'd put a few carefully chosen gratings in it for ventilation. You know the type, with the slots angled downwards to prevent water entry during rain, but providing plenty of air circulation. Drainage holes in the bottom.
You do not have to use an RCBO if you cannot easily get one to fit your CU. You could use an MCB on the non-RCD side, and then a separate RCD in an enclosure or even a fused connection unit type RCD. I think I'd put the RCD inside, not outside in the external box.
Have you established you have sufficient spare capacity on your lighting circuit? Each point must be rated at 100W or actual load if greater, so you only have a max of about 12 points on a circuit.
Also it could be very inconvenient (even dangerous) if indoor lights are disabled by a fault on the outside installation.
Hi, Im setting up some outdoor lighting myself in the next few weeks. Just looking at what was written in regard to how to connect the outdoor lighting to your existing circuits and wondered if anyone can answer a couple of questions:
RCD. Why is this an OK solution?
Whats the reason behind this?
Not exactly sure how the previous owners have got it set up in my house. I already have an external light but not sure if this is wired to the lighting circuit or the downstairs ring which is RCD'ed. Ive got a feeling the latter is true (and some simple testing will confirm the theory).
So is it better for me to extend my existing lighting circuit to accomodate the downstairs lights or if not possible what can I do to make a safe installation using the existing indoor RCD'ed circuits?
The proposed lighting is 6 LED walk over fittings to be recessed into a patio and two wall lights to replace the current halogen spot light.
The current halogen wall light is switched inside. What Id like to do is make this a double switch - 1 switch for the floor level lighting and the other switch for the wall lighting.
I need to understand that if this is currently a spur from the existing lighting circuit or the ring main how I can effectivly control two installations from the one spur. As I understand it should be one spur per fitting??
Basically, because there's next to no chance you'll get electrocuted by most light fittings. I'd be more concerned if the light fittings are largely metallic and not double insulated. I would generally say it was preferable to RCD outdoor lighting, but is rarely essential. Note that TT earthed installations always require an RCD, but there are methods to reduce nuisance tripping.
Because outdoor circuits are subject to moisture that can cause nuisance tripping. When this occurs, it is best that it doesn't turn off all your sockets, taking out your computer, TV and even fridge/freezer in some cases.
It would be OK on the lighting circuit, but best on its own circuit. It is not possible to modify the indoor RCD circuit to remove the possibility of the outdoor circuits providing nuisance trips.
No, this would be fine. The lighting circuits need to be off a fused connection unit, as lighting circuits must normally be fused at 10A or below (some fittings must be 6A or below). Normally, you would use a connection unit with a 5A fuse. This can then drive the dual gang switch, which should either be DP (preferable) or have the neutrals looped at the switch. You can then switch to suitable outdoor cable (i.e. SWA/XLPE/HiTuf) and run to the light fittings. If you must run the lighting off an RCDed socket circuit (knowing the risks), then definitely use DP switches, as some types of faults are neutralearth. The DP switches will isolate the exterior lights, meaning you can turn the house power back on, even without clearing the fault (which might require sunny weather).
Your existing setup probably uses a switched FCU. If so, I'd replace this with an unswitched unit and then feed into a dual gang DP switch. There's no requirement for DP, but it is (very marginally) safer, and, more importantly, provides an easy method to loop the neutrals without requiring crimping or additional terminals floating around.
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