Don't use a UPS?

Weird. My door pass is also not working. Mondays, am I right?


Let’s go ahead and… fix the glitch.

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Completely based on life experience and not speaking for the Other Dan, but I think that until such a point that Glowforge Inc offers replaceable parts in their catalog, you’re going to be forced to send the entire unit back to Glowforge for servicing.

If they start selling individual PSU units like they sell lens replacements and shipping boxes, then presumably they’ll also offer replacement service instructions to go with the replacement PSU when it becomes available.

There are no user replaceable parts. Let me investigate the rest of your question and I’ll get back to you.

To add to what was said here. Simple question. I have a decent surge protector and really unreliable power at my apt (sudden spikes when it goes down and the power co. fixes it) that have already knocked out two TV’s that weren’t plugged into a surge protector. What is the harm in putting what is basically a glorified fuse in front of my GF to break before it’s internal power supply does? Especially considering the whole unit would have to be sent back apparently. Not talking battery backup, just straight surge protection. This seems like a really weird thing that’s not being answered straightly. I love my GF, so I just want to keep it around as long as possible.

A one size-fits-all answer isn’t easy because people have different expectations of what they’re trying to protect equipment against, and no one here can sample the quality of an owner’s line voltage to offer anything but general advice.

Some owners wish to guard for surge suppression when power grids fluctuate in capacity. Others wish to guard against voltage spikes, such as when a lightning strike hits the power grid. One tends to be a slow effect with lower voltage increases, the other a faster effect with significant voltage increases.

But regardless of what is happening with an owners power source, surge suppressor only prevents the averaged peak AC voltage from going above a certain threshold. Repeated micro-transient spikes (in the order of milliseconds) can go much higher, and chip away at the longevity of the unit over time … all relatively unprotected by a surge suppressor.

UPS have filtering and batteries for protection against both long-term and micro-transient spikes, but some of that protection comes at a cost of how much peak power draw they can provide.

What is the harm in putting what is basically a glorified fuse in front of my GF to break before it’s internal power supply does?

But… a fuse doesn’t provide any spike protection. And it doesn’t offer the same protection as surge suppression. A fuse has more in common with a circuit breaker than a surge suppressor. It’s this misconception that they are all the same thing which is the problem.

Awesome, thanks for the info. I guess my only question would be in regards to this:

“But regardless of what is happening with an owners power source, surge suppressor only prevents the averaged peak AC voltage from going above a certain threshold.”

So in such an event as described, would it not be good to have something (UPS, surge suppressor) plugged in to the wall before the GF power supply?

Also if nothing would really do any good, UPS or otherwise, how would it actually harm the GF power supply? As the GF folks seem to be implying, seeing as they recommend against anything but plugging the unit directly into the wall.

Thanks again!

Honestly, if it were me given the situation you described:

I’d get a UPS in the 850VA range if it occurs frequently, and you could probably get away with less if it’s infrequent and you can immediately shut down the Glowforge. If you are using the GF (drawing lots of power) at the same time the power grid ‘snaps’, that could make the damage even more expensive to fix.

I’m not saying a UPS is a bad choice. I don’t think using any protection is. I don’t think a surge suppressor is a bad choice either, if your power is relatively stable and clean to start with. If it’s more or less clean (like most major cities), you probably don’t need much anyways, so a $15 surge suppressed powerbar is a good investment.

Dan’s demurring was a necessary disclaimer of legal obligation in using third-party equipment, not one of offering technical advice.

All he’s implying is that if you purchase and apply protection – hoping it will guard against your self-diagnosed power problems, and you don’t understand what the problem you’re attempting to guard against is – Glowforge can’t be expected to warranty damage from someone suckered into a surge protector that claims “$100,000 Insurance Protection” on the label. Or if the surge protection is ‘worn out’ due to age/neglect.


Hi Dan, a lot of your information on this thread is quite on target, but I think you are here confusing Power Conditioning with Surge Protection.

Power conditioning (or voltage regulation) is what attempts to maintain a consistent RMS (average) AC voltage level as well as filtering noise from the line. Such conditioners also tend to include Surge Protection as well.

The typical surge protector power strips that the lay person normally associates with the term use MOVs (Metal-Oxide Varistors) to shunt high voltage transients to ground. These devices operate an nanosecond speeds.

There are a couple of things people must know about such power strips:

  • To be effective, the outlet they are plugged into must have a proper ground connection (wiring in many older homes will not have proper ground even if the outlets have been changed to have ground prongs).
  • MOVs wear out over time–quickly during major spikes, slowly combatting minor spikes.
  • Thus it is good to have surge suppressors that have lights indicating that they are protecting (usually indicating both good MOVs and proper ground connection).

I have a whole house surge suppressor in the electrical panel. Such a device protects from spikes entering from the main power line. It also protects devices on separate circuits (served by different breakers) from spikes created by other devices in the home. For example, if you have heavy inductive loads–say a big electric motor–that can cause spikes when it is turned on or off. But it will not protect devices on the same branch as that big load. Thus, using a separate suppressor for sensitive equipment on that same branch would be good.


Thanks, I appreciate that. You’re right, I’ve been over-simplifying for brevity. It’s a complex issue depending on the power demands, which is a whole other battle. I was just choosing to generalize power conditioning in together with surge suppression.

Case in point: an industrial workspace will not have the same situation as a home unit.


There are a lot of types of UPS devices. Primarily they vary in two important characteristics:

  • Fail-over vs. Always Online
  • Waveform

Fail-over or Switched

Most inexpensive UPS devices are Fail-over types. What this means is they typically are just monitoring the power line and keeping their batteries charged. When they detect a power drop, they switch to providing power from the batteries to power your device. Good ones detect the power drop quickly and switch to providing power quickly enough that the protected device doesn’t notice it. Thus there are two paths for power to take in the UPS: From the mains to the output and from the batteries, through an inverter to the output.

Always Online

Always-online devices take power from the power line to charge the batteries and to provide power to the same inverter that a fail-over UPS would use. Since a drop in mains power would only interrupt the battery charging, the inverter just keeps outputting the power and the protected device never sees a change.


The waveform can be a critical element of a UPS depending on what is being powered.

Sine Wave

Most of the power you get from the power grid is produced by Generators. Since the voltages produced by these devices results from wires traveling in a circle within a magnetic field, the voltage varies as a sine wave. Because this is the norm, any other grid-connected systems–such a solar power farms–also deliver sine wave power to the grid. This is the type of power that most devices expect–and some can be damaged by any of the other types described here.

Square Wave

The simplest of UPS designs basically just switches power between fixed positive and negative voltages. This is the most likely to cause damage to sensitive equipment.

Stepped (or Simulated) Sine Wave

This is similar in concept to the square wave method, but switches between a number of different fixed values so that it approximates a sine wave.

Each time a square wave or stepped sine wave inverter switches to a new voltage level, it introduces transient spikes. I don’t think they are typically not as high as the spikes a surge suppressor would do anything about, but the high-frequency noise they produce can play hob with sensitive electronics.

Dan has stated:


I fixed @shaug - it only works if the primary group is set to staff, whatever that means. Let me know if any other staff (such as steve) are stiffed and I will it stave off and stuff.


Truly, we don’t know what harm might occur, since we haven’t tested it. There are significant consequences if we were to guess and be wrong, so we don’t. It’s you’re equipment so you’re welcome to try it, but we can’t recommend you do so.

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Ok, cool, I really appreciate the straight answer. I guess right into the wall she goes until the warranty runs out. Do love the unit. Already made some cool stuff (Christmas ornaments) right after getting it setup and the wife is making earrings!