Both 120 volt and 240 volt lights operate with the same 100% output and use the same amount of electricity. A 600 watt light uses the same amount of current in 120 volt as in a 240 volt light. The standard outlet you see in your house is 120 volt.

You may want to get a 240 volt if you plan on running several lights off of one circuit breaker. The maximum wattage on a 120 volt circuit is 1500 watts, per National Electric Code. With the proper breakers or fuses and wire, 240 volt circuits can carry up to 5760 watts. This means that you can plug several high powered lights into a lighting timer that will turn them all on and off on the same circuit. 240 volt is also considered to be more 'stable' because it uses half the amounts of amps. The equation goes like this Amps x Volts = Watts.

Installing a 240 volt outlet is considered 'basic' electrical wiring and it can be done on your own with the correct tools and with a good home electric book. Warning! Electricity is very dangerous and wiring on your own should not be attempted unless it is done so seriously and carefully. If you don't know what you are doing then contact a professional!

Another difference is the lumens per watt of both bulbs. (Lumens is the measurement for the efficiency of the bulb or how much light you're producing for the amount of electricity you're using.) Sodium bulbs produce between 97 and 150 lumens per watt. Halide lights produce 65-115 lumens per watt. An easy way to tell difference between the two types is by appearance. Sodium bulbs appear very yellow-orange, Halide bulbs appear more blue-white.

There are several things to consider when picking the right light for your gardening needs.

First, what type of natural light are you working with? When supplementing natural sunlight, use a High Pressure Sodium bulb to extend daylight in the early spring and fall. You can also use them on low light cloudy days. When no natural light is available at all, a Metal Halide bulb is most frequently used, , which is a very wide spectrum bulb perfect for indoor growing. Halide lights are excellent for vegetative growth for leafy plants like lettuce and basil.

A second factor is bulb efficiency and life expectancy. Sodium bulbs are superior to Halide bulbs in terms of efficiency: they put out more light per watt and last approximately twice as long. Of course, Halide lights provide a much better spectral distribution, so ultimately, the decision about what's best comes down to what's most important to you.

There are a couple of reasons growers switch between bulbs during different stages of plant growth. First, Sodium bulbs can make some plants grow "leggy" and stretched out due to the high yellow to red spectrum they give off. Halide bulbs tend to keep plants "tighter", with less space between internodes. Consequently, some people use Metal Halide lights during vegetative growth to keep the structural growth of the plant nice and tight, but switch to Sodium bulbs during the flowering stage when plants need more light. Although Sodium bulbs don't have balanced a spectrum as Halide bulbs, the intense light they put off does promote flower and fruit development. Bottom line: switching bulbs is a matter of personal preference.

No. Never interchange bulbs between systems unless they are specifically designed to do so. Lots of people ask if they can use a 1000 watt bulb in a 400 system and the answer is NEVER! It's dangerous; the bulb could become unstable and explode. You should also never put Halide bulbs is a High Pressure Sodium system or High Pressure Sodium bulbs in a Metal Halide system. The ballasts are only meant to run the type of bulb they are rated fo. r If you want to interchange bulbs between systems get a conversion bulb; a High Pressure Sodium bulb designed to run off a Halide ballast and vice versa. But remember -- only put the bulb in a system it is designed for.

Conversion bulbs are designed to allow Metal Halide systems to produce High Pressure Sodium light and High Pressure Sodium systems to produce Metal Halide light. This type of bulb allows you to tailor the light source to the growth stage of the plant (again, using halide blue light for growth and sodium red light for flowering/budding) merely by changing bulbs.

Yes. You've got three great Sun System options from Sunlight Supply. The Sun System VI is a switchable ballast, so you can use either Metal Halide OR High Pressure Sodium bulbs. You simply insert the appropriate lamp and set the switch to the correct operational setting.

The other two options allow you to burn both types of bulbs at the same time. The Sun VII allows for the burning of both types of bulbs under the same reflector and Sun System VIII burns each kind of bulb under two separate reflectors. (It's a great choice for use with a light mover.)

It depends on your space and electrical requirements. First, figure out what square footage you'll be working with. But don't just figure for the whole room. Figure out what the plant area is that you need to cover. Multiply length x width to get square footage. You'll need at least 30 watts per square foot. For example: if you have a 4 x 4 area, which equals 16 square feet, multiplied by 30 watts you get 480 watts. That means you need at least a 430 watt light. Keep in mind, the actual amount of light you'll need depends on the amount of light you're the type of plants you are growing like. Some plants like more light, some like less.

We've created a Lighting Calculator to help you figure out the correct number of lights for your room. It will tell you the wattage per square foot of various lighting configurations of your choosing. Play with it to decide what sort of lighting arrangement you'll need.

For optimum lumens, you'll need between 20 (minimum) and 60 (maximum) watts per square foot. There may be several different arrangements that will give you the optimum light energy. For example if you needed 2400 watt, you could fill that wil (2) 1000 watt lights and a 400 or with (4) 600 watt lights, etc.

Metal Halide lamps should be changed at least every 6 to 12 months if you're burning them 18 hours per day. High Pressure Sodium bulbs, burned at 12 hours per day, will last between 6 months and a year and a half depending on the bulb.

A little care should be taken to ensure the safety of your HID lighting system. Remote ballasts should be placed safely out of the way where they can not be knocked over or splashed with water. Ideally they should be off the floor to allow for better cooling and to prevent problems in the case of flooding. Ballasts can get very warm and should not be placed near anything flammable.

Always be sure that the outlet the lamp is plugged into is rated for the amount of electricity you are using. Pulling too much electricity through too small of wiring can cause electrical fires. We suggest putting all lighting systems on GFCI outlets. You have probably seen these kinds of outlets - they have a small red 'reset button on them. They can prevent electrical fires.

A GFCI is not dependent of a ground to function. It does not measure shorts to the ground, it measures the current difference between the hot and neutral wires. A sudden difference of 5 ma. or more, indicating that there is another path for the electricity to flow through will trip this device. It protects any appliance plugged into it, and can also be wired to protect other outlets that are connected to it.

HID bulbs can explode if it is not handled correctly. This will occur if the bulb is very cold when first turned on, or if it contains fingerprint oils or moisture. To prevent accidents, never pick the bulb up directly by the glass - you need to be careful about fingerprints getting on it.. Handle the bulb by the base and wrap the glass body in a paper towel. Handling the bulb through the paper towel, screw it carefully into the lamp body.

If you need to clean the bulb, use a towel lightly dampened with window glass cleaner or rubbing alcohol; wipe all fingerprints, dust and impurities from bulb's glass surface. Let dry thoroughly before installing. After cleaning, always handle the glass through a paper towel. Also, make sure bulb is warmed up to room temperature before installing.

When MH bulbs are turned off they should be left to cool for 20 minutes before re-starting. Turning a Metal Halide bulb on when it is already hot severely shortens the life of the bulb and it can affect the intensity of the light. Metal Halides should be replaced after a year of heavy use.

High Pressure Sodium bulbs can be restarted after only 2 or 3 minutes after being turned off, and they should be replaced every two to three years.

Installing the fixture and reflector is very easy. Locate a stud in the ceiling in the area from which you wish to hang the lamp. Screw in a metal hook capable of holding 40 to 50 pounds and test the strength. Attach a 6 foot chain to the hook(s) on the fixture and hang the fixture from the ceiling hook at the desired height. The chain allows for the easy raising and lowering of the light as needed.

As an alternative to hanging the light from your ceiling you can purchase a light stand.