Two car batteries connection

When connecting two car batteries in parallel, how close must the voltages match?

If they are both standard 12v batteries but one is showing a higher voltage than the other the higher one will drop and the lower one will rise. In other words the voltage of both will change until they reach equilibrium.

• If the voltage is different because one battery is faulty it could fully discharge the good battery damaging it.
• If the voltage is different because one battery fully charged while the other one is fully discharged it is not ideal because there will be a lot of current flow between the batteries and you will get a significant spark as you connect them. Although car batteries are quite robust and should cope with this why risk it if you can avoid it.
• If you are adding another battery to give you more capacity it would be a good idea to charge both batteries before linking them. I have run a twin battery set up in a 4WD and used an isolation switch so that I could never flatten the starter battery when camping and using power for lighting and refrigeration.

What is a 3-phase AC circuit?

What is a 3-phase AC circuit?

A 3 phase AC circuit is a circuit or installation connected to a 3 phase supply. A 3 phase supply uses 3 active lines that may or may not need a neutral wire. A balanced 3 phase load like a 3 phase motor does not need a neutral. Each phase voltage is displaced by 120 degrees. This is due to the cool arrangement in the generator. 3 phases being the most economical arrangement of windings to produce a reasonable smooth load and a a reasonably smooth power source for a motor. On the left side is the 3 phase generators.

Below is a pictorial representation of the 3 phase voltages and winding inside a large generator.

Each phase is also referenced to neutral. So in a 400 volt 3 phase system the voltage between each phase is 400 volts and 230 volts between each phase to neutral. typical application is for a 3 phase motor or a machine that has a high load or several 3phase motors in the machine.

Most factories have a 3 phase supply because they have a high maximum demand ( or a high anticipated load) or have 3 phase motors.

Below is a typical 3 phase motor and circuit.

What happens if I touch both terminals of a 12V battery?

What happens if I touch both terminals of a 12V battery?

Well, let's see:

Nothing happens. I’m still alive and posting on eee-af.

Why? Lets measure the current. (My right finger is on the negative meter probe, and the meter is set to the 2 mA range)

0.026 mA; that's 26 micro amps, that’s 12V × 26µA = 312 micro watts of power being dissipated in my body (as heat).

Nothing is going to get burned with 312 micro watts.

You may wonder why a battery capable of providing 1000 amps, only provides 26 micro amps. Because of resistance, as other have said. Skin resistance is very high, and current is voltage divided by resistance.

Now, if I drop a wrench (with essentially 0 ohms of resistance, Yes I know it’s not really 0 ohms, but close enough for our purposes) across the battery, the current would be 12(volts) divided by 0(ohms), or infinite current. Of course, that’s not possible, but the battery will provide everything it can. This will probably be about 1000 amps. So 12(volts) times 1000(amps) is 12,000 watts. That’s a lot of power, and will easily melt parts of the wrench. A metal watch band or ring can get hot enough to melt, and seriously burn you if the battery somehow contacts it in two places.

So, your answer is nothing will happen because your skin resistance is way too high to conduct any significant current at 12 volts.

For the adventurous out there put a 9 volt battery on your finger and you will feel nothing. Put the same battery on your tongue and it will hurt A LOT. (Don’t say I didn’t warn you). That is because a wet tongue has much lower resistance than skin.

I am adding a picture of what can happen to a wrench.

GFCI Outlets

Are GFCI Outlets Required in Bathrooms?

In most parts of the United States, ground fault circuit interrupter (GFCI) outlets have been required in bathrooms since 1975. So if you’re thinking of having a new bathroom installed or remodeling an existing one, it’s worth being able to answer the question: are GFCI outlets required in bathrooms?

For houses built before 1975, there was no requirement for GFCIs to be installed in residential bathrooms. If you own an older home, you’ll have to upgrade the receptacles if the electrical system in your home is modified.

With this in mind, let’s take a look at what GFCI outlets are and what you need to be aware of when it comes to your bathroom electrical outlets.

What Is a GFCI Outlet?

A GFCI is a type of circuit breaker that shuts off electric power when it senses an imbalance between the outgoing and incoming current. The purpose of these circuit breakers is to prevent electrical shocks from occurring.

Do You Need GFCIs In Your Bathroom?

As we all know, water and electricity don’t mix, so, understandably, there are strict regulations surrounding GFCI outlets.

The National Electric Code states that, at a minimum, a bathroom needs one GFCI-protected outlet. It’s recommended that each bathroom has two or three GFCI protected outlets. The number of outlets you choose to protect is up to you, as long as you have at least one GFCI protected outlet in a bathroom.

You can achieve shock protection with a GFCI circuit breaker in the electrical panel or by installing GFCI outlets. If you’re using a single GFCI outlet for protection, it must be wired for “multiple location” protection; this way, it will protect all the downstream outlets on the same circuit.

Check Local Regulations Regarding GFCIs

Some local codes can vary from the NEC rules, so check with your local building department if you have any questions or concerns.

What’s the Difference Between a GFCI Receptacle and a Circuit Breaker?

A GFCI circuit breaker basically does the same thing as a GFCI receptacle. Consult your trusted electrician to determine which is the right option for your home.

Here are a few points to take into consideration:

• A GFCI circuit breaker will protect everything on that circuit, while a GFCI receptacle only protects the one receptacle and any outlets that are downstream from it.
• Receptacles are easier to install than circuit breakers.
• GFCI receptacles must be installed in locations that are easily accessible.
• A GFCI receptacle usually costs around $15, whereas a GFCI circuit breaker will cost around $50.

A Bad Light Switch 

Light switches are easy to take for granted. They get used thousands of times over the years, until one day they start to fail and need to be replaced. Some signs of a bad light switch are clear. For instance, if there is an audible snap, crackle, or pop when you flip the switch, it’s pretty obvious the switch is defective and it’s time to replace it with a new one.

Are you concerned about one or more of your light switches? Keep reading to learn how to diagnose light switch issues and what to do next.

Why Do Light Switches Go Bad?

Just like any other type of simple machine, light switches have several moving parts. Over time, they wear down. Connections can become loose and plastic parts may break. Someday, each of your light switches will need to be replaced.

Four Signs It’s Time to Replace a Light Switch

When you’ve put a fresh light bulb in the fixture but the switch still doesn’t turn it on, that’s a clear sign that the light switch has died. Here are four more signs that a light switch has gone past its prime.

1. Finicky light fixture
   We’ve all had that one light switch that just doesn’t work right. Sometimes it turns on, sometimes it doesn’t. Occasionally it flickers for a second before turning on. And putting in a new light bulb doesn’t fix the flicker. If this is happening, the proper connections are not being made within the light switch and it’s time for a new switch.
2. The switch sparks
   On occasion, you may see a small spark when you flip the light switch off. This is called a load arc, which happens when the connections within the light switch are pulled away from one another. If, however, there is a large spark that makes an audible “snap,” the light switch has gone bad. If this happens and you see smoke or scorch marks, it is definitely time to get a new light switch.
3. Noisy switch
   When working properly, light switches don’t make any noise. So, if you start to hear any clicking, buzzing, or popping coming from the switch, something within the switch is not working properly. It’s time to replace that switch.
4. Switch is warm to the touch
   When turning a dimmer switch off, you may notice that it feels a little warm to the touch after having been on for a while. This is normal. However, it is not normal for a standard toggle light switch to warm up. These light switches should always feel cool. If a switch feels warm, it’s time for a new one.

How to Use a Multimeter to Test a Light Switch

A multimeter is a handheld testing device used to measure electrical voltage. Electricians and contractors use them to troubleshoot problems on motors, appliances, circuits, power supplies, wiring systems, and more. You can use a multimeter to verify whether a light switch is functioning normally.

To test a light switch with a multimeter:

1. Turn off the circuit breaker that delivers power to the light switch being tested.
2. Uninstall the light switch.
3. Turn on the multimeter and put it on the Continuity or Ohms setting (depending on the model you have).
4. Determine whether you have a single-pole switch or a three-way switch. Single-pole switches have two side terminal screws and may have a ground screw near one of the ends. A three-way switch will have a dark-colored screw (the “common” terminal) and two normal side terminals (the “travelers”).
   1. To test a single pole light switch, touch one multimeter lead to each of the side terminals. When you flip the switch on, the multimeter should show a reading of 1.
   2. To test a three-way switch, hold one multimeter lead to the common screw, and touch the other lead to one of the travelers. When you flip the switch on, the multimeter should show a reading of 1. Then touch the second lead to the other traveler to test it as well.

If your switch fails this test, it must be replaced.

5. Once you have a functional light switch, carefully install it while the power is still off. Don’t forget to turn the circuit breaker back on!

ELECTRICITY HIGH BILL

No one wants to be shocked by a staggering electric bill balance. However, utility rates are increasing almost every year, and the average family’s electricity use has increased 13-fold since 1950! Therefore, it shouldn’t be a surprise that residential electric bills are increasing.

The good news is that there are steps you can take to gain control of your electric bill.

Keep reading to learn how to reduce utility bills without making drastic or uncomfortable changes to your daily lifestyle.

Banish Phantom Energy Draws

Some devices that stay plugged in all the time continue to use electricity even when they aren’t in use. Computer chargers are one of the most common culprits of phantom energy use. Gaming consoles, cable boxes, and digital video recorder (DVR) devices are among the worst power vampires. Unplugging unnecessary cords will help reduce your bill.

Turn Off Ceiling Fans and Lights in Empty Rooms

Every room needs sufficient lighting for reading, watching TV, or just making sure you don’t trip over the ottoman. But overusing overhead lighting can get expensive. Try using lamps to provide direct light right where you need it. And always remember to turn off the lights when you leave a room.

Running a ceiling fan will help cool a room and prevent the need to turn on the air conditioning, which is an energy saver. But remember to turn off ceiling fans in rooms that are not being used. Otherwise, you’re just wasting electricity.

Switch to Efficient LED Light Bulbs

Making the switch to LED light bulbs is a smart decision that will save you considerable money in the long run. LED bulbs use up to 80% less energy than incandescent light bulbs and last up to 25 times longer.

Check Your Home’s Insulation

A house that is not properly insulated wastes energy by making the furnace and the air conditioner work harder than they should. Fixing drafty windows and doors will also bring down the cost of your electric (and/or gas) bill. As with the energy-efficient light bulbs, this investment will pay off big in the long run.

Upgrade to Energy Star Appliances

Many older appliances aren’t very efficient, which could be causing your monthly electric bill to be higher than necessary. Consider upgrading to Energy Star certified models and donate or recycle your old ones. You may even be eligible for a rebate on new Energy Star certified products!

Run Appliances at Full Capacity

Dishwashers and washing machines are two of the most used appliances in the home. But did you know they also use a lot of energy, whether they are full or not? Running them when they are only half full wastes energy. Wait until they’re full before running a load of laundry or dishes.

Set Consistent Thermostat Settings

It is extremely tempting to adjust the thermostat based on fluctuations in the weather. But keeping the thermostat set at a consistent, comfortable temperature will save energy. Decide on a comfortable temperature for when you’re at home, and adjust the thermostat to use a little less power while you’re away from the house. A smart thermostat will make these adjustments automatically and keep your home comfortable all the time.

ELECTRICAL LOOSE CONNECTION

ELECTRICAL LOOSE CONNECTION

Electrical outlets are fastened to outlet boxes, which in turn are attached to the drywall or a wall stud. Over time, the outlet box can come loose from the material it was once anchored to. If you have ever pulled a cord out of an outlet and it felt like the whole outlet was going to come out of the wall, this is probably what’s going on.

Fixing a loose electrical outlet box isn’t just a matter of tightening a couple of screws. You may need to replace the outlet box with a smaller one. You could even need to resize the hole in the drywall. There could also be underlying issues happening, like frayed wires that can pose a real danger to you and your family.

That’s why it’s so important to have a licensed electrician repair your loose electrical outlet boxes.

Warning Signs of a Loose Electrical Outlet Box

There are a few sure signs that indicate an electrical outlet box is loose. It might feel like the whole outlet is coming out of the wall when you unplug a device from the socket. Perhaps you can slide the face-plate side to side. Or did you notice that the face-plate doesn’t lay flush against the wall? All of these are indications of a loose electrical outlet box.

If the outlet box has been loose for some time, so are the wires attached to that outlet. If the wires have been rubbing against any hard objects or sharp edges, there could be significant wire damage. This requires professional repair to ensure the outlet is safe to use.

Other Potential Damage Caused by Loose Electrical Outlet Boxes

If a damaged outlet box is left unaddressed, it can lead to several possible issues. While some of these subsequent problems seem minor, others can be catastrophic.

• Cracked faceplate – After the loose outlet box has been pulled against the faceplate enough times, the faceplate may crack. A cracked faceplate can expose live electrical wires. Don't use the outlet until its faceplate has been replaced.
• Inconsistent device charging – If an outlet’s electrical box is loose, it can cause inconsistent connections for power cords and therefore unreliable charging of electronic devices. Over time, the varying power flowing to the device could damage the device’s batteries.
• Cord damage – If a cord takes force to plug into the wall socket, chances are it will also require force to remove the plug from the wall socket. This can lead to loose wiring connections, making the cord ineffective. Worst case, exposed wires in the cord could result in electric shock.
• Electrical shock – One of the biggest hazards of a loose electrical box is electric shock. If this happens when plugging in or unplugging a cord, it is important to get it fixed as soon as possible for the safety of yourself and your family.

Let Mr. Electric Repair Your Loose Electrical Outlet Boxes

Electricity is a powerful force. When dealing with electrical issues in the home, it is always best to call in a licensed professional to take care of the problem. This is not only to ensure the job is done correctly but also for your own safety.