Look at it this way....how many outlets around your house do you have that currently have nothing plugged in to them? They're currently on with power going to them with nothing plugged in.

You might pay a few pennies a month on the electric bill for those indicator lights on all the time, and being on all the time one MAY burn out prematurely making you think that the protector is worn out when its just the light burnt out, but that can happen to the one that you're not worried about. If there is a small surge,, it will take the brunt of it and would be "protecting" even though nothing is plugged in, and if it was a big enough of a hit, the protected light might go out because the surge properties had exhausted by protecting nothing that was there and you may have to replace it. One might say if that happens you're throwing money away having to buy another to replace one that died protecting nothing, but that's a discussion you'd have to have with your wallet. It dying from protecting something that was plugged in is worth it, but like I say, one would have to question the cost of having to replace one that died protecting nothing. Other than that, there's no problem with leaving it turned on with nothing plugged into it. One MAY argue about cheap surge protector and power strips being a firehazard, but that could happen no matter if something is plugged in or not or if it's turned on or off. A faulty one will go no matter what. But considering one in good shape that's been rigorously tested for safety, there's no hazard in doing what you're doing anymore than your wall outlets that stay on 24/7 without anything plugged into them.

It probably uses a tiny amount of power, whether devices are plugged into it or not. It may provide some protection for other household circuits connected via the wiring, but this would depend somewhat on its electrical topology and the rise time of the offending circuit transient surge.

If nothing's plugged into it or it's toggled to off, there's likely no draw. If the toggle is on, there might be something miniscule, like for a small LED if there is one. This may be a spec the manufacturer can provide. Or, plug it into a Kil A Watt device if you have one, that will definitively answer the question.

An electrical device needs to be plugged into a stand alone surge protector (ie, not one installed as part of a structure's electrical feed) to have protection. Something that's plugged in elsewhere is, well, plugged in elsewhere.

Note there is a so-called "phantom load" from many electrical devices that are plugged in but turned off. Otherwise, how would your TV, as an example, be able to respond to a turn on signal from a remote? Any device with a remote control has a low level draw when turned off.

"An electrical device needs to be plugged into a stand alone surge protector (ie, not one installed as part of a structure's electrical feed) to have protection. Something that's plugged in elsewhere is, well, plugged in elsewhere."

This is partially incorrect. Whole house surge protection protects every appliance within the house from external surges passing the protection device on service entry wiring (within its performance limits) and aids protection of devices within the house from surges generated within the house limited only by the various inductances of the wiring between the source of the surge, the device to be protected, and the surge protector as a function of the rise time of the surge waveform.

Where other conductors besides the service wiring enter the house, additional surge protection against local lightening is also desirable due to this inductance. Stand-alone surge protection may help protect circuits close to them depending on how well they react and the bonding impedance to whatever counts as a true ground (water pipes and grounding rods, but not necessarily when a strike is nearby). Dealing with multiple current paths such as TV cables, ethernet cables, intercom cables, and telephone lines can be complex. A local surge suppressor may be configured to minimize voltage between hot and neutral, but the pair may rise in voltage together relative to some other attached cable, still allowing damage. Nearby lightening can induce currents into wiring as common-mode transients.

Roam around the https://tpssurge.com/ website for indications of how far one can go in bounding a residence with protection.

tl;dr: a local stand-alone surge protector may be insufficient in some cases, and a service entry (whole house) surge protector may be sufficient in other cases.

The question was on current draw, not effects of lightning or supply line surges. I'm happy with what I said.

No name-

What bad thing are you worrying will happen?

Does it hurt to leave a surge protector on with nothing plugged in? No.

I guess it's all a matter of interpretation. I was taking it that OP wasn't talking about vampire load, but more of a safety thing, such as a fire hazard

To me it simply sounded like free floating anxiety but without a clear articulation of a specific concern.

I didn't know their intentions either so I just addressed both fire and vampire load concerns

I interpreted the question to be whether the device would be damaged without a load as implied by the title: "Does it hurt to leave a surge protector on with nothing plugged in?"

Some surge-protected outlet strips have built-in USB charging ports, and they will draw a little power even if turned off, but not much.