I wish to install some outdoor lighting for meat poultry (they need lights on 24/7 so they can eat 24/7). I've done some minor electrical work, even installing a circuit, but I'm a beginner.
First some background: this is in a developing country (Philippines) and aesthetics are not needed, so the wires will be above ground (anyway the ground is very wet).
No code of any sort exists. The only concern is safety. I've done some electrical work, in theory ("Thevenin equivalent circuit", lol) and in practice (installing an AC with circuit breaker, dishwasher, etc, in the USA), but am hardly an expert.
Here is my plan:
Refer to the diagram embedded herein: Some of this had been built, some of it is proposed. Apologies for my artwork.
Blue is neutral wire (-), Red is hot (+), green is ground. 220V is the mains power supply in the Philippines. You will note I installed on my own an "earth" circuit (ground) downstream of the main circuit box. This is because in the Philippines, as is common in developing countries, they don't have ground wires. So I installed one myself and much to my surprise it seems to work (or so it is implied by my multimeter, it might be a false sense of security however, but let's assume it works).
A = main circuit box. It has an old fashioned 'pull throw switch' and two 30 Amp fuses that blow once and have to be replaced. It is NOT connected to ground.
B = a junction box that I made, connected to a homemade ground
C = standard three-wire cable, connected to a three wire (+, -, grd) outlet.
D = two wire light bulb fixtures, THAT WILL BE EXPOSED TO RAIN OUTDOORS, electrically connected to the outlet in C. I will try and keep these bulbs dry, but they are ordinary light fixtures. Sorry but I cannot get outdoor light fixtures, and note that only two wires (hot, neutral, no ground) go to these light bulbs.
My questions:
1) will I risk electrocution if the lightbulbs collect condensation (it rains hard here)? Probably. But won't the ground stop any real damage to anybody who happens to be standing close to these bulbs? Keep in mind that there's no ground wire at the bulbs, only at the outlet junction which is five (5) meters away from the bulbs. How do you ground a lightbulb anyway? All the fixtures have but two terminals, (+,-), no ground. I've seen some fancy outdoor bulb holders made of metal so I guess you would connect a ground wire to the metal?
Anyway, if there's a short, won't the fuses at the main circuit box "A" melt/trip/blow?
2) at arrow "E", do I need to install, in series, a "RCD" (Residual Circuit Device)? I am not even sure they sell them here in the provinces of the Philippines; maybe there's one for sale in Manila I can have a friend mail to me. What good is an RCD here? I suppose to detect any short at the lightbulbs? Do I have the RCD placed correctly, downstream of the junction box B? Or does it matter (probably it does not matter, it can be upstream of box B?)
3) Last but not least, should I forget using 'mains' 220 V power for wet terrain, outdoor lights, and try something safer like LED 12 volt transformer lights? Of course that's an easy answer, but I prefer answers to 1-2 first before this 'obvious' easy answer. Also please resist the temptation to say: 'hire a certified electrician in your area', because in my area in the middle of nowhere there's no certified anything, or rather I'm about as qualified as the next guy (lol).
Diagram:
Best Answer
Your design is dangerous because you don't have safe light fixtures. Outdoor light fixtures, especially at 220V, need to safely insulate all electrical conductors. In an environment full of moisture and active, moving animals, you need fixtures that are secure and sealed. If you can't buy these, maybe you can make some, but don't expect regular indoor fixtures to be safe.
Let's think about how this system gets dangerous. Some of the wiring gets exposed, and a person or animal gets between the hot and neutral legs, completing the circuit. This could happen with two adjacent puddles of water, maybe one touching a hot and the other a neutral. Or a puddle and a rake that's pierced some of your above-ground cabling.
Your "ground" wire doesn't help. Bonding neutral to ground is good because it means that a loose hot wire that touches some exposed metal (or other good conductor bonded to ground) will blow the fuse quickly. You're not in an environment with lots of good conductors; even wet dirt may not conduct well enough to blow the fuse. If you had for example a metal walkway and a nearby metal pipe, you should definitely bond those so they can't be separately energized. But if you're just talking about an electrical system out in a field, bonding the field to neutral doesn't buy you much.
An RCD (residual current device) or GFI (ground fault interruptor) may not help much either, because again you're not likely to leak current to ground. However, these might be a little more sensitive than your fuse so they could help a bit.
The safe approach here is to use proper light fixtures designed for outdoor use in wet areas. These can be low-voltage or high. Low voltage is safer, because even if the fixtures or wiring fails the available energy is not enough to kill you. But a 220V setup that includes sufficient protection for your junctions and the light bulbs would also be relatively safe.
If you stick with your design, at least realize that your ground does not make it any safer. Protect your fixtures and junctions from moisture and from access by people and livestock.