Surge protectors are usually made of components that cause a short when a surge happens, protecting the equipment downstream. It usually pairs with some kind of overcurrent protection (breaker, fuse, sometimes GFCI) to protect against the short the surge protector itself caused.

Having chained surge protectors it actually quite common. You may have a surge protector in your breaker panel, then in your powerstrip, then in the power supply of the device you have plugged in. Most good quality ATX power supplies have built-in surge protection for instance. They also all tend to have overcurrent protection too. The breaker panel has breakers (duh), the power strip may have a simple breaker too, and the device may have a fuse. In the UK, the plug itself may have a fuse, plus the breaker from the utility company.

The risk from chaining surge protectors is that it increases the risk of false triggers if one of them is defective. But it may also provide better protection. All in all, I wouldn't worry too much about it. Just don't overload that power bar and whatever it is plugged in.

And (I think) the copper circuits are so close that quantum leaps can occur -- electrons can just decide to jump from one piece of copper to another, straight through silicon or anything else, simply because the copper is so close. This means a VCC line can be giving charge to an unpowered neighboring circuit or memory cell without magnetically affecting it.

The manufacturers are well aware of risks, for liability reasons if nothing else, and have contained them in the uniform-electrical-code mandated manner. The system is no more risky than any other plugged-in appliance. We don't need to invent problems. Extension cords are just extension cords.

Appliances themselves with their own input fuses and captive cables are less risky, although some kind of internal wiring short could still get all melty.

It's true that sizing the plugs that way does prevent you from plugging a 20A appliance into a 10A extension cord, which makes sense.

And I don't see how putting 10-15 amps through a cord, plug, and outlet that routinely handle 15 amps downstream everyday causes a fire risk. My house doesn't freak out when I operate a space heater, and I don't see why it would freak out if I push a space heaters power through that exact same setup.

The cord is dangerous, in the sense that you could get shocked by your generator. You can get shocked by the thousands of rusted, rewired, half functioning generators on Craigslist without every using a cord like this.

Roll-out extension leads are extra dangerous though, even if fused. I have a relative that had to jump out of a second floor window on a construction site when someone set all of their batteries charging on a wrapped up extension lead, which rapidly started a fire. I assume it happened faster than the thermal cutoff could trigger.

Lightning is like 300,000,000 volts. No surge protector is strong enough for that.

The NEC does have restrictions on the size of a breaker supplying different types of receptacles. 20 amps through, say, a 18AWG extension cord shouldn’t be that dangerous as long as the cord uses high temperature insulation. But your point is good: a fuse protecting the cord would be a very sensible feature. (Even better would be ground and/or arc fault protection in the cord, but that gets expensive.)

The danger is overloading. Back in the days when the main things you plugged in were incandescent lights and space heaters, this was probably a big issue. With computer equipment and LED lights you have to have a lot more stuff - many outlets' worth - to reach the circuit's maximum capacity.

If the circuit and "surge protectors" are rated for 1800W (15 amps x 120V), officially you should limit yourself to 80% of that for continuous loads which is 1440W, so you can supply 14 laptops or small small desktops that use 100W each, or over 200 raspberry pis on USB chargers that use 5W each, and either way you're going to need a lot of outlets before you come anywhere close to that limit.

At least that's a rough estimate. Power factor could decrease that number by up to 50% and you can use the full rating for intermittent loads; I'm not certified to know the fine print. Point is that 10 computers can easily use less power than a single space heater.

A better unsafe solution is to upgrade the breaker without upgrading the wiring or outlet. Breakers are usually $5-10 and most wiring won't burst in to flame from an extra 5 amps.

Note that fuse-in-plug does not keep you from overloading a circuit; it only helps when the device itself malfunctions.

Disclaimer: sometimes it will burst in to flames. You shouldn't actually do this.

Yup. But that engineering issue is the responsibility of the designers of the DC/AC converter "box"!!!

> Then you have the issue of protecting the 120V loads. You can get more than 20A of current out of the alternator, which pushes what you can safely put through standard extension cords.

Naw!!! The car's alternator charges the car's 12 Volt battery, and the DC/AC converter "box" takes the 12 Volts from the battery and makes 120 Volts AC available at the female output sockets. So, if I plug the male end of an extension cord into one of those sockets and connect the female end of the cord to the male end of a power strip with female sockets and have my office lights and electronics, the "loads", connected to the power strip, no more current will flow in the extension cord than is requested, as usual, by the loads. A cord that can carry 16 Amperes, at 120 Volts, would be moving

16 * 120 = 1920 Watts

As I type this, my office is drawing 52 Watts. With my server with its 8 core AMD processor and my laser printer, still looking at a lot less than 1920 Watts. And the printer gets only occasional use and then for only seconds at a time.

The DC/AC converter has more than one female socket supplying 120 Volts, and from that and an ordinary extension cord could drive the refrigerator, toaster, and microwave oven -- again much less than 1920 Watts.

If I start to overload the DC/AC converter, not very likely for my loads and a converter that can supplyk 4000 Watts, I trust that the converter will have a circuit breaker. In that case, this approach to emergency electric power should be not much more of a safety challenge than normal usage.

Note in all of this, the circuit breaker in the house does not get involved, remains ON, and waits for the utility power to come back on. Then the lights in the kitchen, front hall, etc. will come back on, and I will plug my office and kitchen loads into the wall sockets again, disconnect the DC/AC converter, put the car back in the garage, wind up the extension cords, make some notes, and f'get about the outage!

One little issue is: If the Web server computer was running when the power went out, might there be a way to have power to that computer not be interrupted all the way until the power comes back on? Yup: With some shopping, can run the server computer off another box, not very big, that has a little battery inside that can keep the computer running for a few minutes while I switch over to the DC/AC converter and again while I switch back to the utility power.

For the Hacker News audience, this is conversation is drifting into kindergarten level talk: I'm SURE Hacker News has MANY very well informed engineers on how to have un-interruptible electric power to computers in a server farm and also to the whole farm.

For more, once I wrote a math paper on detecting zero day problems, gave an invited talk at the NASDAQ headquarters, and got a tour and overview of the engineering they did for un-interruptible NASDAQ service, uh, including a remote backup server location. Such magnificent engineering has long been available.

Here I am just trying to contribute to the issue of this thread, using the engine in a car to supply standard 120 Volt A/C electric power. I'm just mentioning that for short term power outages, maybe only a few hours at a time, should be able to do okay with just a normal car and a little box that can supply 4000 Watts of 120 Volt A/C power from a 12 Volt DC battery. That's all I'm trying to do.