Plugging one power strip into another? Yea or Nay?
So on every single extension cable/power strip there are UL warnings to not plug one power strip into another...
But I've got an 8-outlet Furman PL-PLUS power conditioner in my rack, and I need 9 or 10 outlets... I'm not using an immense amount of power (my lights don't dim or anything when I turn on the rack), so is it safe to hang a couple more devices off of the unit with an outlet extender?
If you plug each power bar into the other, you'll save a bunch on the electrical bill
Sorry, but it was too easy LOL
Warnings are created by legal advisors for clueless consumers. The only danger is that the aggregate of all the plugs exceeds the current capacity of the wiring and switches ie. if you plug a bunch of space heaters, the toaster, iron, etc etc AND there is a problem with the fuse box, you may start a fire and live to sue the power bar manufacturer.
In a studio, we plug many, many devices that for the most part, consume tiny amounts of current and therefore one sometimes would consider plugging a power bar into another. You may consider plugging the most hungry devices closest to the source (wall) (like tube amps, powers amps, console (if it's big))
From a power factor audiophile perspective, there is an advantage to avoiding cascaded power bars but even if you subscribe to this, we're only talking about getting that last 1% more (albeit a gearslutz priority) but I am taking the context of your question from a safety point of view.
For pro installs we might plug one small strip into a large heavy duty strip, but would not go beyond that. IMO the biggest downside of cascading AC strips and power plugs is that intermittent or slightly resistive ground connections become more of a possibility, and annoying inexplicable noises may crop up.
UK power strips have fuses in each so that has (overloading) safety largely covered.
OK far too many are cheaply made but that is a different issue.
Put your 'wall warty' non earthed units on a secondary strip then earth is not much of an isue and the power drawn will be negligible so relatively safer.
What i've generally been told is that if you are going to cascade power outlets, make it into a star formation so that say 4 strips extend from the 4 sockets of the first strip, instead of each one being plugged into another
When talking to Furman about my older AR1215 (a device that gives you 120 volts out with any input voltage from 90-130) and trying to get the latest protection, which is not destructive, they just suggested cascading the AR1215 from a new PL Plus 2. So, I gathered that it's not too bad to do.