Hey all. I just came across this informative read on electrical safety for indoor grwing situations.
With DonG&T's narrow escape yesterday it got me thinking along with a few other im sure.
Anyways i found this article in the Urban Gardener Magazine. Good info in here.
Can I grow in here? Electrical Safety Part 1
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Urban Garden Magazine ⋅ August 31, 2010 ⋅
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Filed Under amps,
ballasts,
electrician,
electrics,
fire,
Issue 12,
load centers,
safety,
volts,
watts
Last issue we reviewed the various factors that need to be taken into consideration when assessing a potential space for some indoor gardening action. We looked at insulation, ceiling height, water, drainage, ventilation, size, accessibility, and protection from pests. However, we omitted a very important factorone so crucial that we felt we needed to pay it our total and complete attention with a special focus: Electrical Safety.
Whats an indoor growers worst nightmare? pH problems? Dont think so. Clogged drippers? No, think again. Spider mites? Youre not even close! Okay, youre probably way ahead of me by now. Every growers worst nightmare has to be
an electrical fire! Often these fires are caused by faulty electrics and/or overloaded sockets. Novice growers are constantly putting themselves and their loved ones at risk by not planning their grows right. And here at Urban Garden HQ, we want all of us to sleep tight and our plants to bloom copiously 365 days a year, year after year. Surely, thats what we all want out of life, isnt it?
The most important thing to get your head around when setting up a new indoor garden is your power requirement. Modern indoor gardens use HID grow lights, air conditioners, heaters, extractors, oscillating fans
and those watts add up fast! So were going to take a look at the proper procedures for installing circuits and bringing in the necessary electrical wiring to safely supply all of your power-hungry devices. Next, were going to review exactly how to specify and install all of the circuits for a ten-light flowering room setup; this process will show you how to plan a similar setup for your own indoor garden, on virtually any scale.
Heres the good news: Anyone with their fair share of common sense, the right tools, and a healthy do-it-yourself spirit can safely install the power for almost any indoor garden setup. However take heed: you need to pay careful attention to what you are doing and work from a predetermined planTheres no room for guesswork when planning your indoor gardens electrical system.
And, once you have planned your installation, its a must to run your plan by a licensed electrician before doing anything. This is the smartest thing you can do.
Residential Electricity
Okay lets take it from the top. Before bringing power to the garden, heres a quick review of the residential electrical system. In Canada and the United States, a residential electrical service drop consists of three wires that enter a home from an overhead pole, or sometimes from an underground service feed. Of these three wires, two are separate 120-volt lines of different phase, and one is a neutral line. This type of service is called a single phase electric power system and it can supply households with 120- and 240-volt power circuits.
In the picture below, you can see the main point of entry for the three service wires coming in from above and entering a conduit on their way to the main service panel of a residence.
From their main point of entry into the residence, the three service wires proceed to the main panel where they connect to the meter, and to bus bars where circuit breakers snap in. The circuit breakers provide branch circuit protection for the various appliances and rooms in the house. The main service panel will always have a main fuse or circuit breaker that can cut power to all of the branch circuitsAlways turn this off before working on the panel or any of the circuits. Service capacity for residential panels is usually 100, 150, or 200 amps at 240 volts. Older homes may have outdated panels with lower capacities. Before setting up in an older home, it is highly recommended that you upgrade your main panel to comply with current standards. Its the only way you can ensure your electrical system will be safe.
This picture shows a residential panel with the door open to expose the branch circuit breakers. Note the conduit at the top left where the three service wires (two hot and a neutral) enter the panel. In the middle left is the meter, which measures overall electrical consumption. Each of the circuit breakers provides power to a certain area of the house or to a specific appliance. The blue sticker next to the breaker in the middle indicates the main shutoff.
At the main panel, a fourth wirethe groundis introduced into the household system. The ground provides a path for current to escape in case of a circuit fault. On a proper main panel installation, there will be a copper grounding rod driven at least ten feet into the earth, with a wire that runs up to a grounding bus bar in the panel. NOTE: Some older electrical systems have what is referred to as a mechanical ground, where the ground is made from the neutral bus bar at the main panel. The mechanical ground method is not appropriate, and if you have an older panel with a mechanical grounding system, it is recommended that you upgrade your panel, or install a grounding rod and locate all of your ground wires on an isolated grounding bus bar.
The picture below shows a grounding rod driven in to the earth, with a wire that runs up to the main panel. This is the proper method of grounding your electrical system. Fault currents are carried directly to the earth.
From the main panel, you can create 120-volt and 240-volt power circuits for your garden by installing the appropriate circuit breaker(s) and wiring. Before selecting and installing the new circuits, first determine how much capacity you will need. In order to do this, make a detailed list of the equipment you will be using and how much power each device consumes, in volts, amps and watts. NOTE: Devices running on 240-volt power are more efficient than those running on 120-volt power. So when selecting components, always buy everything you can in a 240-volt configuration.
Volt (V): A measure of potential electrical energy, akin to electrical pressure.
Amp (A): A measurement of the flow of current.
Watt (W): The overall measure of energy being consumed, in relation to time. A kilowatt hour is the usage of 1,000 watts for one hour. This is the measurement by which customers are charged by their utility company.
Formulas to remember:
- Watts = volts x amps
- Amps = watts / volts
- Volts = watts / amps
With any two variables, you can determine the third.
CATALOG YOUR EQUIPMENT
Now to assemble the equipment list: For this task, its a good idea to use a spreadsheet because it can perform all the calculations for you, and you can easily analyze electrical needs for different configurations by changing variables like the number of lights, fans, etc. This setup will be running a ten-light flowering room, a six-light vegetative room, fluorescents to light some racks for cuttings, a 5-ton AC system, plus accessories like pumps and fans. The table below shows the breakdown of the equipment and electrical needs. Look at the devices to see the voltage, amperage, and/or wattage they use. Remember, you can determine the third variable if you know any two. Fill in the table completely and calculate your amperage requirements.
Since many of the devices for the model setup will be running continuously, de-rate the total amperage of the devices to determine the appropriate size breaker. To de-rate the amperage for devices running more than three hours straight, divide the total amperage that the devices are consuming by .80.
Appliance# UsedVoltsAmpsWattsTotal AmpsDe-rated Amps1,000W Light102404.75114047.559.375400W Light62401.945611.414.255-Ton AC12403276803240Fluorescent101200.35423.54.375Exhaust Fan2120336067.5Oscillating Fans81200.56045Pumps51200.22411.25Duct Fans61201.251507.59.375Misc.2120112022.5(Download this MS Excel template at
www.powerboxinc.com/hydroplanner)
DETERMINE YOUR POWER NEEDS
Now that youve determined how many amps the devices use, and de-rated that number, assess the size of the circuits needed. Keep in mind, each major appliance group will require its own circuit. In this case, you will need to install the following circuits:
1. The first circuit you need to install will supply 240 volts and 60 amps to a lighting controller that will supply power for ten 1,000 Watt high-pressure sodium lamps and ballasts.
2. The second circuit will be 240 volts and 20 amps, to supply power for a lighting controller that will power six 400W metal halide lamps.
3. The third circuit will be 240 volts and 40 amps, to supply the power for a 5-ton air conditioning system.
4. & 5. The last two circuits will each be 120-volt, 15-amp circuits and will supply power for all of the accessories and controllers.
Appliance
Circuit Voltage
Circuit Amperage/
Breaker Rating
Lighting Controller 1
240
60
Lighting Controller 2
240
20
5-Ton AC
240
40
120V Accessories
120
15
120V Accessories
120
15
SURVEY YOUR PANEL
Naturally, make sure that your panel has the capacity to handle your electrical needs. This setup would require at least a 150-amp panel to run the proposed loads and have room to install three 2-pole circuit breakers and two single-pole circuit breakers. A panel survey is the first thing you should do before evaluating the potential of any grow location.
SELECTING THE PROPER WIRE GAUGE
Now that you know the size of the circuits and breakers to be used, you need to determine the size (gauge) of the wires needed. Before doing this, lets quickly understand how many wires are needed for each circuit.
- A 120V circuit consists of a single 120V line (from either phase), a neutral line, and a ground, for a total of three wires.
- A 240V circuit consists of two 120V lines (of different phase), a neutral line, and often a ground, for a total of four wires. Some legacy 240V circuits and 240V circuits 20A or less may use a 3-wire configuration, which consists of two 120V lines (of different phase), and a neutral line (not a ground), for a total of three wires.
Circuit Voltage:120V240VWires:120V Phase 1xx120V Phase 2xNeutralxxGroundxxNote: A 120V circuit can be made by using either 120V phaseIt is vital to select the proper wire gauge to support and deliver the power to your garden. Using the correct size wire for the amperage requirements of the circuit allows power to flow to your devices with minimal resistance, and prevents the wire from overheating and potentially starting a fire. Always remember that the smaller the wires gauge, the larger the wires diameter.
Two factors determine the wire gauge required for installation. First is the length of the wires, and second is the amount of current the wires need to carry. The table below provides a guideline for the wire gauge required for the circuits. For medium length wire runs of 75 feet and under, use 400 circular mils per amp. For longer wire runs of 75 to 150 feet, calculate requirements by using 700 circular mils per amp.
Wire Gauge and CapacityAWG
Circular Mils
Current Capacity (Amps) Under 75′
Current Capacity (Amps) 75-150
1
83694
209
120
2
66358
166
95
4
41738
104
60
6
26244
66
37
8
16512
41
24
10
10384
26
15
12
6529
16
9
14
4109
10
6
16
2581
6
4
In our example, the distance is less than 75 feet, so our calculations are based on 400 circular mils per amp.
Circuit 1: 65 feet of wire for a 60-amp, 240-volt circuit. 60 amps x 400 circular mils per amp = 24,000 circular mils. Referencing the chart reveals youll need to use 6-gauge wire, which has 26,244 circular mils. A total of 4 conductors are needed: 2 hot, a ground, and a neutral.
Circuit 2: 65 feet of wire for a 20-amp, 240-volt circuit. 20 amps x 400 circular mils per amp = 8,000 circular mils. Referencing the chart reveals youll need to use at least 10-gauge wire, which has 10,384 circular mils. A total of 4 conductors are needed: 2 hot, a ground, and a neutral.
Circuit 3: 50 feet of wire for a 40-amp, 240-volt circuit. 40 amps x 400 circular mils per amp = 16,000 circular mils. The chart shows that 8-gauge wire would be sufficient, but its close. When in doubt, always go with a lower gauge. In this case, use 6-gauge wire, which has 26,244 circular mils. A total of 4 conductors are needed: 2 hot, a ground, and a neutral.
Circuits 4 & 5: 65 feet of wire for each of two 15-amp, 120-volt circuits. 15 amps x 400 circular mils per amp = 6,000 circular mils. Referencing the chart, you should use 10-gauge wire for this circuit. A total of 3 conductors are needed for each circuit: 1 hot, a ground, and a neutral.
BRINGING CIRCUITS TO THE GARDEN
So far youve determined: how many circuits are needed, the necessary capacity of those circuits, and the wire gauge needed to support the current the equipment will be consuming. The next step is getting the wires from the main panel to the place where they need to bethe garden area. This is another step that requires very careful planning. In an installation such as this example, there is no other safe choice than to use Electrical Metallic Conduit (EMT).
EMT is metal tubing that comes in various diameters and it shields the wires from weather and any other outside contact. Its easy to work with, provided you have a few of the right tools. Dont use something like Romex that can be cut easily or punctured in a rugged garden environment. Choosing proper tubing for your conduit is one step that helps everyone sleep soundly at night!
Next, decide where the termination for each circuit will be and then plan an accessible route for themfrom your main panel, where each conduit will begin, to the location where the power is needed. You will have to make various bends in the conduit along the way; try to make as direct a route as possible so as to minimize the wire length and minimize conduit bends. Fewer bends make it easier to pull the wire through later. Connectors are available to mount conduits to the panel enclosure, to splice pieces of conduit together, and to join them to almost any type of electrical box. Mount the EMT securely using the companion clips.
The photo below shows a 1 diameter EMT conduit originating from the main panel and running along the side of a house to the grow space. A conduit like this can carry the four wires needed for the 240-volt, 60-amp circuit for the lighting controller.
This photo shows an EMT conduit using a connector to directly enter the interior of a residence via a hole drilled straight through the wall.
Now youre getting somewhere. Once the conduit is secured firmly in place, its time to start pulling the wires through. Be sure to buy at least 10 feet more wire length than you need for each circuit you are pulling.
When buying wire, buy:
BLACK for 120 volt phase 1
RED for 120 volt phase 2
WHITE for Neutral
GREEN for Ground
When pulling wire, youll need a fish tape, which is a thin, flat steel wire ribbon on a reel, used specifically for pulling wire through conduitbe sure to get one that will accommodate more than the length you need to pull. Push the fish tape from the termination point of the conduit back through until it reaches the entrance at the panel. Make sure the main is OFF!! Carefully pull about two feet of fish tape out so that you can securely tape the wires (youre about to pull) to the fish tape. Using black electrical tape, attach the wires in a staggered manner so that they will round bends easier when they are being pulled through the conduit. With one person feeding the wires in at the panel, and another person reeling-in the fish tape at the other end, carefully feed the wires all the way through the EMT conduit from the panel to the room. Repeat this process for each circuit, until all of the raw wires for each circuit are in their respective conduits and sticking out at both ends.
Now, thats easy, isnt it? Yeah, I know, not reallyits actually pretty rough. But dont fretyoure actually getting closer to the part where you hang the lights, and take some cuttings, etc.
INSTALLING THE CIRCUIT BREAKERS
Now that all of the wiring is in, its time to install the individual circuit breakers. If you havent done so already, make a trip to your local electrical supply store and get the five circuit breakers specified for the five circuits:
- 60A Double-Pole Breaker
- 20A Double-Pole Breaker
- 40A Double-Pole Breaker
- 15A Single-Pole Breaker
- 15A Single-Pole Breaker
The cover to the main panel should already be off; if not, remove it to expose the bus bars where the breakers actually snap in. Starting with the first circuit, a 240-volt, 60-amp breaker, locate the four 6-gauge wires for the lighting controller circuit where the conduit enters the panel. Trim the wires to length and secure the white wire to the neutral bus bar in the panel. Do the same for the green ground wiretrim to length and secure to an isolated ground bar. Next, trim the red and black wires, strip the ends about 3/8, and attach them to the terminal lugs on the 60A breaker. Tighten the screws very tightly. Route wires neatly on the side and snap the breaker into its location.
This picture shows the main panel with the protective cover removed. Circuit breakers easily snap into place once wires are attached. The neutral wire for each circuit connects to a neutral bus bar and the ground to a ground bus bar.
This photo shows a close-up of where the hot wires connect to the terminal lugs of the breakers. A double pole breaker has two hot wires (red and black). A single pole breaker has one hot wire (either a red or a black). You can spot a double pole breaker by its double thickness and the bar tying the two switches together.
Repeat the breaker installation process meticulously for each set of wires and each circuit breaker. It is critical to connect all neutral wires securely to the neutral bus bar and the ground wires to an isolated ground bar. Once all of your circuit breakers are installed and all wires are securely attached, double-check everything for accuracy. Make sure all wires are routed without being pinched and make sure breakers are firmly in place. If everything looks good, replace the security cover on the panel, but make sure to leave the main and all of the breakers in the OFF position.
TERMINATING YOUR CIRCUITS
This junction box allows connections to be made from incoming wires to devices or power outlets.
Now you need to terminate each circuit and install the devices. Its a bit beyond the scope of this article to discuss installing all of the garden components, but we will show you how to terminate the first 240-volt, 60-amp circuit and install the lighting controller that powers all of your lightsthe largest power consumers in your garden. Test with a meter to ensure there is no live current at the termination point before beginning to work on anything.
When the wires from the 60-amp circuit punch through the outside wall to the inside room as in the earlier photo, they enter a junction box like the one pictured below. Inside this box, wires are connected together and routed to their destinations through additional conduits if necessary. In this case, this junction box ties into a Powerbox lighting controller that powers and controls all of the ballasts and lights in the garden.
INSTALLING A LIGHTING CONTROLLER
Now theres one last step for this circuit that is equally as important as all of the previous steps. You need to install the high-voltage lighting controller to handle the switching of all of the ballasts and lights. The high-voltage lighting controller takes more punishment than any electrical component in your garden, so its essential to pick the best quality. Cheap wall timers and inadequate controllers are often the cause of overload that can lead to fire. The on and off cycles of heavy amperage loads cause extreme arcing, and a lighting controller needs to handle these extreme conditions without being prone to failure.
Firmly secure the lighting controller to the wall in a location near your junction box where the circuit enters the room. Route the cable from the 240-volt lighting controller (e.g. Powerbox) into the junction box and secure with an EMT-type terminator to the junction box. Splice each of the four wires from the lighting controller main cable to the matching wires from the incoming circuit (black to black, red to red, white to white, green to green). Use insulated lug-type connectors, which are available at electrical supply stores. Once the connections have been made, close-up the junction box. You are now ready to test this circuit. Safety first: 1. Make sure the Powerbox (lighting controller) breaker is OFF. 2. Go to the main panel and turn ON the 60-amp breaker for this circuit. If the breaker stays on, all is good so far. Go back to the lighting controller and turn the breaker ON. You should now have live power at the lighting controller!
Although each device will be a little different, repeat the circuit termination process for each of the remaining four circuits. None of them will be any more difficult than the one youve just done. For the 120-volt circuits, try to locate your outlet boxes close to where they will be used. This means extra conduit, but its worth it to avoid using extension cords, which are a garden hazard.
This photo shows a 60-amp circuit terminating with a Powerbox lighting controller, which in turn runs ten 1,000-watt Galaxy digital ballasts. This particular setup also uses 10 Flipbox® switches to double the production of the garden by running two parallel rooms with 10 lamps each, all off of one 60-amp circuit. All equipment is securely mounted to the wall with steel struts.
So much done in so little time. If you are building or upgrading an indoor garden that you hope will provide years of bountiful productivity, you need to build a solid infrastructure. This requires an investment of time and money, but the rewards are huge. I cant tell you how many setups Ive seen that have wires duct-taped together and that use pie tins as lamp reflectors. Are you kidding me? How can situations like that not eventually lead to a fire? And to make matters worse, these are the most under-productive gardens around. Whether your indoor garden is your passion or your business, make the right moves and dont become another statistic at your local fire department.
Now youre at the point where its time to hang the lights. I dont think you need me anymore. Im outta here! Peace.
P.S. Safety First! Consult with a qualified electrician before doing anything!