The following was taken from an article at https://www.plymouthenergy.com/5-electrical-safety-tips-you-should-know-for-your-home/
5 Electrical Tips to Protect Your Home
1. Replace or repair damaged power cords Exposed wiring is a danger that cannot go overlooked, the NFPA wrote. If you see the protective coating on a wire is stripped away, be sure to replace it or cover it with electrical tape as soon as possible. 2. Don’t overload your outlets Every outlet in your home is designed to deliver a certain amount of electricity; by plugging too many devices into it at once, you could cause a small explosion or a fire. If you have a lot of things to plug in, use a power strip (an energy saving one of course!) that can safely accommodate your needs. 3. Avoid extension cords as much as possible Running extension cords through the house can trip up residents; this can cause injury and damage to the wire or outlet if it causes the cord to be ripped out of the wall. If you find yourself using extension cords very often, consider having an electrician install new outlets throughout your home. 4. Keep electrical equipment or outlets away from water Water conducts electricity, so even the slightest exposure to this dangerous mix can lead to injury. Make sure you wipe up any spills to ensure that plugs don’t get wet. 5. Protect small children from hazards Toddlers and small children are very curious– and they love to explore just about everything. Parents of small children should put tamper-resistant safety caps on all unused electrical outlets. In addition, all loose cords should be tidied up and put out of reach to avoid kids tugging on them.
How many things can you plug into an electrical outlet before it catches fire?
So how do you find out how much is too much? Actually, it's pretty easy. To determine how much electricity you're using with all of those holiday decorations, you just need to do a little math. The formula looks like this:
p/e=i (wattage divided by volts equals amps).
Say you're using 2,000 watts of power with your holiday lights and other decorations. You divide that number by the volts in your house (usually 120) and you come up with 16.6 amps of current that you're using. With a 20 amp electrical outlet, you're using around 80 percent of the available current, which is the most you should be using per circuit.