Mains electricity, typically a higher voltage AC waveform used to deliver electrical power to households. In North America 120V, 60Hz, in most European countries 230V, 50Hz. What most people will plug appliances into.

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1answer
41 views

Adding a resistive path between live conductors and earth - safety issues

(Note: I am in the UK so the terms 'line' and 'neutral' refer to the two live mains conductors) I am trying to establish a list of safety issues which I should be aware of if I decide to introduce a ...
0
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1answer
75 views

Three questions about the use of a transformer in switching power-supply

In this document (an introduction to switching power supplies) a boost-mode switching power supply is presented: it has a simple inductor, diode, capacitor and load. Then (page 9) it is specified that ...
0
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0answers
20 views

Retrofitting synthesizer with internal uninteruptable power supply?

I have an old Roland synthesiser (MC-909 sampling groovebox) that I would like to retrofit with a backup battery both to avoid loosing work and just so I can take it down the park with some ...
2
votes
2answers
67 views

Transformer hum - DC offset? Does this cause transformer breakdown?

I have an integrated amplifier that I like, but it hums - it's an Arcam A22 and contains a big toroidal transformer. It sits on the desk right next to my monitor and I can't live with it. I just ...
6
votes
1answer
140 views

Overhead transmission line crossing over interstate highway

I live in Minnesota, and a few years back, Excel Energy constructed a massive power line stretching from Monticello, MN to Fargo, ND. This is not the exact photo of the power lines, but it's very ...
0
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1answer
91 views

Rapidly switching on and off a 12v power supply, bad idea?

I was just wondering if this would be a bad idea, the power supply is connected to the mains power and would only undergo this at a max of 10 minutes at a time. would this cause any damage to the ...
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2answers
118 views

Why did England not use the same split-phase system as the USA?

The residential electrical service in England and the USA differ only by the neutral wire splitting the single-phase in to two lower voltages. Why didn't they add one inexpensive wire to get all the ...
-3
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0answers
60 views

Home mains power/ relays: Is this safe?

So far I have build a wooden box with a removable panel which has 2 sets of dual plug sockets. Their live and earth wires are connected to the end of a plug and wire. Their neautruls are each ...
11
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4answers
958 views

Schuko plug wiring

Why it is not important where we connect our hot and neutral wire when connecting them to our Schuko plug? Is it because current flows in both directions? It is only important that our ground wire ...
1
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2answers
56 views

Eliminate mains common mode ripple from external power supply with poor isolation

I've got a number of battery powered devices which require periodic recharging. I'm using notebook chargers to provide for the input voltage and they work fine... most of the time. Occasionally they ...
0
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0answers
17 views

DIY Mains Power Distribution

I am trying to create a product unit with an enclosed microcontroller that can function like a WiFi-enabled bulb (albeit with an entire enclosure and an enclosed audio speaker). I am a total beginner ...
0
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0answers
58 views

Are there any issues connecting Neutral and Live at once to the supply line? [migrated]

A normal plug point has the wiring structure of the normal cct diagram I've drawn below. I'm thinking about plugging a device into the outlet in a permanent way and keep the switch closed and control ...
0
votes
1answer
72 views

What happens if there is a fault in the neutral wire between the grounding pole and the centre tap of the transformer?

I was reading through some SE questions/answers on residential power transmission and came up with two scenarios I'm unsure about: Assume that your house is wired properly (with no degradation), but ...
1
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1answer
73 views

Voltage drop-out after lightning strike

A powerful thunderstorm rolled through my area yesterday and something happened that I had never noticed before. Many times before when powerful thunderstorms with lightning rolled through, the AC ...
2
votes
1answer
82 views

Transformer and a relay in series - but function like in parallel, but not exactly

I've been doing some planning to build a home automation system on top of the existing power infrastructure of my house. The first thing would be making my light switches smart. My original plan is ...
0
votes
1answer
97 views

Is it safe to pass 240AC power through the ACS712 current sensor?

I'm trying to build a little Arduino circuit to automatically turn on a dust collector when my saw is on and drawing power. My plan is to use an ACS712 current sensor (30 amps) to detect and transmit ...
2
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0answers
52 views

Is there a good book on designing for electrical safety with AC mains power? [closed]

Is there a good book on how to design for electrical safety, particularly when using AC/mains power? I have look on Amazon without finding anything that seemed appropriate. This topic is largely ...
3
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0answers
35 views

Can I use the Omron G6RN relay where reinforced insulation is needed beetween coil input and switched circuit?

I want to use a relay to control 230V power to an electric motor. I'm considering using the Omron G6RN relay: http://datasheet.octopart.com/G6RN-1-DC24-Omron-datasheet-10910301.pdf According to the ...
0
votes
2answers
100 views

Why is only MOV allowed for surge suppression according to IEC 60950-1

IEC 60950-1 prescribes that if a surge suppressor is used in a primary circuit it "shall be a VDR". The document informs that a VDR is sometimes referred to as a "varistor or a metal oxide varistor ...
2
votes
2answers
37 views

Where can the detailed requirements for EU Low Voltage Directive compliance be found?

I'm designing an appliance that probably has to comply with the European Low Voltage Directive. I've been searching for a guide on how to design a product complying with this directive, but I haven't ...
0
votes
1answer
65 views

Stepper Motor Everything in Order, Not Moving

So I'm very confused. I have everything hooked up according to their various diagrams and am attempting to run the following recommended test code: ...
2
votes
2answers
119 views

Can a household device limit consumption to avoid tripping circuit breaker?

A common problem for resistive loads, like household heating appliances, is that peak current is drawn on startup. I have come across ICLs (inrush current limiters), which are cheap components. Do ...
5
votes
1answer
45 views

How does a fuse affect creepage reqirements?

I am designing a mains-powered device that has to comply with IEC 60079-15 (Non-incedive industrial eqipment). Creepage distances in this standard are inherited from IEC 60664, pollution degree 3. For ...
0
votes
1answer
60 views

Usefulness of line EMI Filter on bench power supply

I have read this pdf file about EMI filters. I'm about to construct a variable bench power supply of 12V/5A. Will there be any usefulness to add an EMI filter to the primary windings of the ...
1
vote
2answers
124 views

Why does this transformer draw so much current?

I've been working on a DC power supply to provide about 10 mA at 200 V. The simplest way (not dealing with a switching power supply) seemed to be using a transformer to step 120Vac up a little bit to ...
0
votes
2answers
90 views

When building world devices what wall voltages should you expect?

I want to build a dishwasher safe toaster (more details in other questions), So Simplicity of design is a must. Fortunately toasters are among the simplest of electrical devices consisting of nothing ...
3
votes
1answer
76 views

Strange Earth Voltage Reading

Ok, my first question here. In my spare time, I run a small PA company. On Saturday, I had a concert at a sports center where I´d never been before. Power for the event came from a standard 5-pin, 16A ...
2
votes
1answer
138 views

What are the effects of powering AC devices from a square wave?

I've been playing around with some ideas about building my own inverting power supply, to power AC devices from a car battery. I've heard of designs that just feed a square wave into a transformer to ...
0
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0answers
31 views

3 channel vs. 4 channel 120/240 power meter

So I live in the US, where we have center tapped power for residential use, with two hots and a single neutral wire. My question is what would be the potential effective difference in power ...
2
votes
2answers
116 views

Does any company manufacture American AC power plugs with insulated pins?

In Australia and some other places, good-quality AC power plugs have "insulated pins". This means that there is a short length of insulation covering the base of the pins. Darren Yates writes that ...
0
votes
1answer
35 views

Is ACS712 isolation sufficient for SELV?

Can the Allegro ACS712 current sensor be used to measure mains current with enough isolation so that the isolation between the mains (230V) side and the logic side of the sensor is enough to achieve ...
2
votes
1answer
116 views

How to read this transformer label

I have the following transformer that takes in 117V and steps down to 12V and 9V. However, I don't understand the label. "PUR" and "RED" are listed as 117V, does that mean PUR is power and RED is ...
0
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1answer
44 views

Connecting shielding for high and low voltages

I have design a power distribution PCB with high AC(230V) and low DC(<10V) voltage power rails. Both are going to be connected to my board by separate cables. Each of those cables have shielding ...
0
votes
1answer
59 views

Why does oscilloscope show large amplitude when I touch the probe?

When I touch the probe I see a 50Hz sine wave with an amplitude of about 100V from peak to peak. I understand that 50Hz is the mains hum picked up through my body, which acts as an antenna, but where ...
7
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2answers
370 views

Which Earth should a chassis be connected to: supply, or local?

I have a doubt regarding the earthing of an appliance and its separate isolation transformer. Consider the following simplified schematics; this is my first guess at which earth each chassis should be ...
0
votes
1answer
81 views

Why isn't there a voltage drop across the Main Wires?

As far as I know the power to my home is directly coming through a Step-Down transformer, so why isn't there a voltage drop and how are all the houses hooked up to the same transformer getting the ...
0
votes
2answers
86 views

Negative Feed on Electrical Lines [closed]

I live in a New York apt and I woke up last Saturday (5/30/15) because our power went out at about 7:30 am. A quick check with the bldg's doorman revealed that it was just our apt and not a total ...
1
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1answer
48 views

Safe way to interface directly with HomePlug / Powerline

I'm looking to do some research into the actual messaging used by powerline adapters. I'm aware of the standards, but I'm specifically looking to see where real devices deviate from the standard, and ...
1
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0answers
21 views

Confirming the use of a RIFA snubbing component across 120V relay switch

I have a mains relay switch (Packard C230B 2 Pole 30 Amp Contactor 120 Volt Coil) which allows me to turn on my pre-amp based on the existence of AC voltage on the amplifiers AC output plug (which is ...
0
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0answers
30 views

Measurement of 230VAC relay noise

I have an MCU which is switching a load, which is connected to 230VAC via a two pole relay switching live and neutral. The load is another MCU board with its own ACDC. My problem is that when the ...
0
votes
1answer
74 views

Why is mains voltage showing up on my oscilloscope from MagSafe shield?

I'm theoretically aware of grounding issues that can come up when using an oscilloscope [e.g. as explained in this video], but I can't make sense of this one: I have a device under test (imagine an ...
0
votes
1answer
126 views

triacs from dishwasher

I have PCB from broken dishwasher and I would like to learn something from it. There are 6 smaller - STMicroelectronics Z7S, 1A triacs and one bigger STM T4 3570. My guess is (cannot verify it now) ...
1
vote
1answer
114 views

How did I manage to not be hurt after accidentally making an electric contact between mains wires?

Warning: mains is dangerous, often fatal and should not be messed with. I accidentally touched both live and neutral of a 230 AC mains via dupont wires after a shower (still wet feet). However I ...
0
votes
2answers
83 views

What needs or works better with DC than with AC electric?

Solar power is becoming more popular, and it seems a lot of people who have solar panels have a DC to AC inverter. It seems ironic to convert DC electric to AC, and then the the AC gets converted back ...
1
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3answers
74 views

Complex power calculation across parallel loads

I have the following problem which require the calculation of Load L3 apparent power, real power and reactive power. I have done the following as the described in the figure trying to get 2 ...
-2
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2answers
80 views

Double the current capability of a mains socket by wiring another in parallel [closed]

I have an appliance that I know draws more or less 16A under 240VAC, but I only have 13A sockets around. Is there any off the shelf solution?
0
votes
0answers
38 views

What topologies are used for synchronization of AC power in a micro inverter?

I would like to know the design pattern utilized in syncing the AC Sine output of a micro-inverter (or inverter in general) with the grid. Please also give any good resources for designing an ...
1
vote
4answers
127 views

earth as a voltage reference

Why is the neutral point of the alternator hooked up to the earth which makes all the voltages of the lines with reference to the earth. Doesn't this makes us more risky to the shocks? I think we use ...
2
votes
2answers
83 views

Mixing two or more AC sources to handle overload

Can I mix two or more AC sources to handle overload and maintain a stable voltage of 230V AC? For example if power from solar panel cannot handle a heavy load can I mix power from different source ...
0
votes
3answers
218 views

Fast 220v AC power failure detection

I'm building an AC-Detection circuit. I want to detect when the AC power has failed ASAP so that I can react very quickly. (like 1-3ms should be enough time) This was my first idea. It works in ...