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Because an ohmmeter works by putting a potential difference (voltage) across a load and measuring the resulting current (the current will be inversely proportionate to the resistance). In a live circuit there is already current flowing through the load so (at best) the reading will be inaccurate, at worst the meter will be damaged.
What else can I help you with?
Is an ohmmeter connected in series or parallel?
You almost NEVER do. 1) The circuit should be off and/or disconnected when using an ohmmeter. 2) It should be in parallel with the component as far as the rest of the circuit is concerned, but alone in series with the device its measuring.
Why must a fuse or Switch never be fitted to the secondary of a CT circuit?
Secondary of a CT should never be opened to avoid damage to CT. Fuse or switch may lead to opening of CT secondary accidentally.
In electrical circuits what wire protects the operator?
Earth wire is meant to protect the user in case there is earth fault in the device or circuit. Only earth wire alone is not sufficient. It needs to be provided with suitable circuit breaker that breaks the circuit automatically.
How does a switch control an electric device?
A switch basically represents a gap in the electric circuit. Electric current can pass through a circuit only if it is complete. An incomplete circuit can never pass a current through it. When the switch is in the 'off' position, the circuit has a break (gap) in it. When you put the switch in 'on' position, the circuit wire join and the circuit gets completed.
Why rated current should flow in the secondary for short circuit test in transformer?
Open Circuit test is done to find out core losses of the transformers.which include Eddy Current Losses and Hysteresis Losses only, if during open circuit test secondary will have some load then I2R losses due to load current in secondary as well primary will be included in test results which is not desired while performing Open circuit test.
Is an ohmmeter connected in series or parallel?
You almost NEVER do. 1) The circuit should be off and/or disconnected when using an ohmmeter. 2) It should be in parallel with the component as far as the rest of the circuit is concerned, but alone in series with the device its measuring.
What meter must NEVER be connected to a circuit when the circuit power is turned on?
An Ohmmeter.
Why we should never handle electrical appliances with wet hands?
Because water is a conductor, and water dripping from your hands may drip down to an energized circuit, and effectively create a trail from that circuit to your hands, causing you to get electrocuted.
What items of equipment should be used to test if the electrical circuit is live?
The most important piece of electrical safety equipment that is used in the electrical trade is a voltage detector. You never start or do anything to a circuit until the circuit is tested and confirmed de energized. Once the circuit is confirmed de energized pad lock it in the off position and keep the key on your person. Never ever take any ones word for it that the circuit is turned off. Get the meter out and confirm that the circuit is de energized for yourself.
Is the current in the circuit 80 percent of the fuse rating?
It should be, yes. Never higher.
How do you take care of an ohmmeter?
Never connect the ohmmeter's leads across a voltage.On an analog meter, adjust the zero before use.Turn your ohmmeter off when not in use, to protect against voltage drain.When your ohmmeter's battery is low, or your meter won't be used for a while, remove the battery to prevent damage to the meter from battery leakage.
Why should you never place a fuse in a neutral conductor?
In case of a fault (short) the device could still be energized even with the fuse blown. this means, a fuse in the neutral would never blow in a fault to ground, resulting in a very dangerous situation.
Where do you set the dial when you are measuring resistance on house current?
YOU DO NOT "measure resistance on house current".You never measure resistance of anything that has any path to any source ofpower ... not to a wall outlet, a battery, a windmill, a solar panel, etc. You onlymeasure resistance when all power is REMOVED from the circuit or componentyou're measuring. Then, the range you choose for the ohmmeter depends onthe component or circuit you're measuring, NOT on how it's powered when it'sturned on.
Should AC circuits go to or from positive battery terminal?
You would never connect any part of an AC circuit to a battery.
What is a brown fuse and why should you never replace one with a penny?
I believe the question should be what is a BLOWN fuse and why should you never replace it with a penny? A blown fuse would be one that has been over stressed and has burnt out or blown out to protect the wiring or other part of the circuit. A penny would bypass the fuse which is the safety measure in the circuit. Bypassing a fuse could cause a fire or serious damage to the device.
What is the function of a build in an electric circuit?
I have never heard of an electrical term "build" in an electrical circuit.
Why must a fuse or Switch never be fitted to the secondary of a CT circuit?
Secondary of a CT should never be opened to avoid damage to CT. Fuse or switch may lead to opening of CT secondary accidentally.
