[kosma]

It's not very different from daisy chaining normal extension cords - safe if you know what you're doing (not exceeding the current rating on any of them). Most surge protectors are fused, making them safer to daisy-chain than normal extension cords.

[quickthrowman]

> It's not very different from daisy chaining normal extension cords - safe if you know what you're doing

It’s not safe, and it’s expressly forbidden by the NEC, see 11.1.5 below:

> 11.1.5 Extension Cords

> 11.1.5.1

> Extension cords shall be plugged directly into an approved receptacle, power tap, or multiplug adapter and shall, except for approved multiplug extension cords, serve only one portable appliance.

Daisy chaining extension cords is unsafe and not recommended. Only use extension cords that you’ve inspected and are properly rated for the environment (don’t use indoor cords outside, don’t use an outdoor extension cord outdoors unless it’s GFCI protected) and power usage of the device you are powering.

Any time electricity has to flow through a splice or mechanical connection, the possibility of a loose connection causing an arc and subsequent fire exists.

It’s unlikely to happen to you specifically, but it does happen and avoiding electrical fires is a good thing if it can be avoided.

Daisy chaining power strips is also forbidden by the NEC:

> 11.1.4.2

> The relocatable power taps shall be directly connected to a permanently installed receptacle.

[dvdkon]

Yes, there is a risk of failure involved with anything electrical, but I don't see why anyone would consider chaining extension cords inherently dangerous enough to ban. It increases the number of connections, but that's a miniscule risk compared to the 5+ connections an extension cord might have on its own. The only significant risk I know is people disregarding the max amperage rating of everything in that chain.

For anecdotal experience, I've had both extension cords and wall plugs fail (nothing serious thankfully, but they did get a bit melted), but in those cases it had nothing to do with my extension cord chains, but rather an internal connection failure.

[sgarland]

As an aside, increasing the length of extension cords can cause premature failure of some devices (mostly motorized tools, especially cheaply-made ones) if the wire gauge is inadequate, due to voltage drop.

As a general rule, I wouldn’t run tools past 50 feet on anything smaller than 12 AWG (and really, 14 AWG is the smallest I’d go for any length; anything smaller isn’t safe for most loads).