Stealing power from the phone line: the trick that saves less than €2
Drawing electricity from the phone line: 48V and 20 mA deliver under €1.50 a year. Is it worth it? We look at the ultra-frugal emergency light trick.
English · Original discussion in Spanish · Published
Ultra-frugal emergency light: can you steal electricity from the phone line?
With electricity bills at record highs, an old trick from the energy survival handbook is making a comeback: powering a light bulb from the phone line's current. The idea is nothing new; it has circulated for years on responsible-consumption forums and rests on a technical fact: the traditional telephone network provides 48 volts of direct current with a 20 milliamp limit. The math is quick: 48V · 0.02A = 0.96 watts. A total of 8.76 kWh a year. At today's electricity prices, the saving comes to less than €1.50 annually.
Voltage, current and the limits of the phone network
The copper phone line is not an infinite power source. The 48V available at rest rises to 75V AC when a call comes in, which requires a filter to avoid frying the circuit. What's more, the maximum draw is capped at 20 mA, and extracting any more can cut off the service. The phone network has the advantage that the exchanges have batteries and generators, so the line stays alive during a power outage. That makes it a candidate for an emergency light, but only that.
The real math: less than €1.50 a year
Someone with a calculator in hand made it clear: 20 mA times 48 V gives 1 W, which multiplied by 8,760 hours a year is 8.76 kWh. After the tariff hike, that means a saving of under €1.50. The return is so ridiculous that it doesn't even offset the risk of losing your line or facing a fine for connecting non-approved devices to the public network.
Legality and risks
Connecting any device to the phone network without approval is illegal in Spain. Providers can detect abnormal consumption and users face sanctions or loss of service. That's why, despite the videos and tutorials circulating, the commercial product doesn't exist and never will: there's no margin for a bargain, only for a risky hobby.
Conclusion: as a piece of ingenuity, fine; as a savings strategy, nonsense. The ultra-frugal emergency light is more urban legend than real solution. And anyone trying to live off the phone's current had better prepare to be left in the dark... and without calls.
Most shared
Related forum discussions
With electricity bills at record highs, an old trick from the energy survival handbook is making a comeback: powering a light bulb from the phone line's current. The idea is nothing new; it has circulated for years on responsible-consumption forums and rests on a technical fact: the traditional telephone network provides 48 volts of direct current with a 20 milliamp limit. The math is quick: 48V · 0.02A = 0.96 watts. A total of 8.76 kWh a year. At today's electricity prices, the saving comes to less than €1.50 annually.
Voltage, current and the limits of the phone network
The copper phone line is not an infinite power source. The 48V available at rest rises to 75V AC when a call comes in, which requires a filter to avoid frying the circuit. What's more, the maximum draw is capped at 20 mA, and extracting any more can cut off the service. The phone network has the advantage that the exchanges have batteries and generators, so the line stays alive during a power outage. That makes it a candidate for an emergency light, but only that.
The real math: less than €1.50 a year
Someone with a calculator in hand made it clear: 20 mA times 48 V gives 1 W, which multiplied by 8,760 hours a year is 8.76 kWh. After the tariff hike, that means a saving of under €1.50. The return is so ridiculous that it doesn't even offset the risk of losing your line or facing a fine for connecting non-approved devices to the public network.
Legality and risks
Connecting any device to the phone network without approval is illegal in Spain. Providers can detect abnormal consumption and users face sanctions or loss of service. That's why, despite the videos and tutorials circulating, the commercial product doesn't exist and never will: there's no margin for a bargain, only for a risky hobby.
Conclusion: as a piece of ingenuity, fine; as a savings strategy, nonsense. The ultra-frugal emergency light is more urban legend than real solution. And anyone trying to live off the phone's current had better prepare to be left in the dark... and without calls.
Most shared
Related forum discussions
- Ultra-frugalism in electricity · 19 replies
- . · 167 replies
- Oil boiler vs. natural gas boiler · 107 replies
Also available in: Deutsch
Summary of a discussion on Burbuja.info - Foro de economía, actualidad y política., translated from Spanish and reviewed before publication. Read the full discussion (19 replies).
More summaries
-
AliExpress Tariffs: €3 Per Category, Not Per Package
The EU removes the €150 exemption: a basket costing €13 now totals €20 due to tariffs, charged by TARIC category, not per package.
-
Non-LED bulbs: why incandescents are making a comeback
Incandescent bulbs are back in shopping carts at €1 apiece as growing eye discomfort is attributed to cheap LED lighting.
-
Stuck Faucet Eccentric: Limescale, Hemp, and DIY Fixes
A faucet eccentric stuck by decades of limescale and hemp. Discover which remedies work (vinegar, torch, wrench) and when to call a plumber.
-
Sleeping Without Underwear: Health Benefit or Myth?
Does sleeping without underwear improve your health? Anecdotes keep piling up, but science remains silent. We look at the pros and cons of this practice.
-
43 million Americans in poverty: twice as many as 50 years ago
43 million people now live below the poverty line in the United States, double the figure of 50 years ago, while 1.5 million homeless children triple the Great Depression level.
-
Gambia, the land of prawns: from etymology to the fishing vest
Did you know Gambia means 'land of prawns'? Discover the curious connection between a fishing vest, its etymology and the real usefulness of camouflage in…