It depends on what the load will be on the fuse (not an individual outlet).. My guess is that you are overloading the fuses. I would consult a certified electrician in your area, because for fire saftey you should probably look at having an extension box set up below your normal fuse box which could then run all these lights. Already with 32 I suspect you are well above the legal load limits of the fuse and with 32 more you are asking for trouble.

However, I do not know your setup, and would recommend you discuss it with a certified electrician (for your own safty)

Whoa! You have 32 40W bulbs already? On a single circuit? Single circuits are usually rated for 15A or 20A, which is 1650W or 2200W. Remember that includes every other household light, TV, microwave, etc. on that circuit.

Your 32 bulbs are using 1100W - 1300W depending on the exact spec so you are already pushing it. Doubling that will almost certainly blow the breaker. If you have modern circuit breakers then feel free to try this, its "relatively" safe and easy to reset.

You probably have two circuits to your home and could potentially arrange the load. But I guess since you are asking here, it would probably be better to get a qualified electrician to advise on a safe arrangement.

The National Electrical Code (in force in most US jurisdictions) calls for using no more than 80% of a circuit's capacity for "constant" loads, which means those that are on for 3 hours or more per day. You haven't given enough information to tell whether you're keeping within those guidelines. How many circuits do you have at the greenhouse, and what is their capacity? How is the load distributed? A 15 amp circuit can handle 1500W of continuous load within these guidelines, a 20 amp circuit can handle 2000W.

Using extension cords as "permanent" wiring is never a safe bet in the long run and using them in damp/humid environment is asking for even more trouble. If they are running outdoors (like from the house to the greenhouse), it's very unsafe and also against code. (And yeah, I know people like to scoff at electrical codes, but they exist for a reason - safety.)

And of course, if those fluorescent fixtures aren't designed for outdoor/damp use, you're running a not insignificant risk of shock and lower risk of fire by using them "off label."

One cheap and important thing to do is to have the electrician replace the outlets with GFCI (ground fault circuit interrupter) outlets, of a capacity that match your breakers (they come in 15 amps or 20 amps varieties). That adds an extra level of protection in case of a short circuit (such as one caused by water). If the outlets are in your greenhouse, they're probably already of that type.

I'm wondering why you need fluorescent lights in the greenhouse? I'd think that even in winter, natural light would be stronger than that provided by fluorescents.

As others have said, it seems like the main issues are (a) circuit capacity and (b) whether your fixtures or electrical cords are being exposed to moisture. An electrician can help with (a), or you can read off the capacities in your circuit breaker box and then multiply by 75% or 80% for safety. (b) is an issue for your current setup as well.

A possible area of concern, depending on the size of your greenhouse, is the heat generated by the fixtures themselves: 2560 watts of electricity is enough to warm a good-sized room. Depending on how well-insulated and well-ventilated your greenhouse is, the heat could build up enough to fry your plants, though probably not enough to start a fire. Of course, you need to leave some clearance between the lights and the greenhouse walls.

If you do need the supplemental light, have you thought of using more-modern narrow-bulb fluorescent fixtures or high-intensity (HID) grow lights instead? They're more expensive than shop fluorescent lights but are more efficient, so you'd use less wattage, generate less heat, and save a bundle on electricity in the long run. Some HID lights are designed for outdoor use, so should be safe even if exposed to the weather. Depending on your greenhouse construction, you could even mount the lights above it, allowing the heat to dissipate naturally while the light reaches your plants.

Electiction came out today.He fixed everything up so I can have all my lights on and the cords are enclosed in covers.It's all grounded and he assured me that it's very safe now. I need the lights because I live in Washington State and in fall and winter it's always gray and cloudy. Also I think with the lights the green house will be warm enough to grow plants in. But I'am wondering how much my electic bill will go up.

Your 32 40W bulbs will run slightly over 1kW depending on the exact bulb, say two kWH per day, which I think will be about 15c/day, maybe $5/month.

I'm sorry, multiply everything by 10, since you're probably running for nearer 20 hours each day, not 2! So around $50/month extra. That sounds much better ... or worse :(

Thanks so much for the info. I was really worried that it would cost a fortune to run all the lights.I found a chart on line and it will actually be about $100. a month (I have 32 light fixtures with 2 bulbs in each one) I think it will be interesting to see if they keep the greenhouse semi warm in the winter.