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Home Server Room Power Upgrade and Multi-Room UPS

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96 pointsmonstermunch85 comments

> Some may ask why the outlets are installed upside-down, its common in commercial settings to do this as it means if the cord sags down, only the ground prong will be exposed. Things can also get lodged between the two hot prongs if the outlet is the normal way up, like this from an image I stole from reddit

This is very insightful. I've seen outlets installed upside-down to designate them as switched, but never heard any other justification.

This actually makes sense and the charred measurement tape further demonstrates what can and has happened.

Dug up the Reddit link for those also curious: https://www.reddit.com/r/OSHA/comments/ilb7wq/please_unplug_... and maybe original post was to Twitter: https://twitter.com/meyerweb/status/1289302216826925057

You'll see outlets installed 'correctly' (with ground being the highest pin) in hospitals. I've heard that the explanation for their most common orientation is because of our fascination with faces. I'm sure there's a better reason – but I do think it attributes to it.

Neither is incorrect. Either orientation of the outlet is NEC code compliant in the United States and it's really just a matter of preference.

Personally, I like "normal" outlets to be ground pin down and switched (as in, connected to a lightswitch) ground pin up.

I don't have a problem with outlets with the ground prong up, but...

1. Why isn't your plug all the way in the socket? 2. Why haven't you replaced that outlet that doesn't hold a plug properly?

Humans are lazy. Overall, it was less effort to be forced to sometimes have to deal with upside down outlets, rather than convince everyone that there is a specific and universal orientation.

It's not a great reason, but here we are.

Brand new outlet, brand new high quality extension cord

https://imgur.com/a/0DXJXkw

I guess high-gauge wires are more hazardous in the socket.

This is a benefit to our (UK) sockets, as laid out in BS 1363 and used in some other countries.

The cable exits the bottom, not the front, so it doesn't matter how thick or heavy it is, and pulling it out of the socket by the cable is very difficult.

Further, our earth pin is at the top by default, and our line and neutral pins are insulated to the extent that if the plug is far enough out of the socket to expose the uninsulated portion of the pins, it is no longer far enough into the socket to be receiving any voltage.

https://media.rs-online.com/t_large/F3236252-01.jpg

Problem is when you step on them, it hurts like hell...

I hear this mentioned a lot. I've never trodden on a power plug.

How is this even a concern?

Do people in America go around treading on cables all the time or something?

It's more that because the cable exits the bottom of British plugs and it's bottom-heavy, if you drop a power cable on the floor, it will invariably land pin-side up.

I used to live in the UK, and as a messy teenager my room wasn't the neatest...

US sockets aren't switched, so the only way to remove power from a device is to unplug it. Most things have power switches but not everything, and some people are very keen on unplugging.

Ahhhhh that might actually explain a lot - people's behaviour is affected by the design in that they end up unplugging more frequently due to the lack of a switch in the socket, so more cables laying around unplugged, versus the UK where plugs tend to be left in the socket but can be physically disconnected using the switch.

I just cover it in Legos.

The earth pin is also longer than line and neutral pins so it should be the last one out in most circumstances (as well as opening the shutters only after engaged)

Yep, and the line terminal is closest to the opening, so if the cable is forcibly ripped out from the plug, line gets disconnected first, and earth usually last. Along with many other benefits (like an inline fuse) that I didn't mention in my post as it wasn't relevant to the posts I was replying to. :)

I used to be annoyed with getting (various European formats) of plugs out of recessed sockets.

I'm not so annoyed now that I'm aware that the recessed nature is actually really helpful to avoid that failure mode.

I originally trained to be an electrician. That said, the argument for ground pin down was if a plug "falls" out due to gravity, the ground prong will be the last pin to break connection. Though honestly this is really unnecessary as if the hot and neutral have broke, what current is there to ground?

Another reason is a lot of manufactures of grounded/polarized wall-warts and GFI plugs tended to orient the damn things for ground pin down making ground up installs prone to falling out. So you wind up with electricians following ground down to accommodate this design flaw (or habit).

I dislike the nema 5-15 blade design as it doesn't hold up well to wear. I'd much prefer a pin and sleeve design with the plug recessed in the socket like CEE 7/Schuko. But that's another argument.

> That said, the argument for ground pin down was if a plug "falls" out due to gravity, the ground prong will be the last pin to break connection. Though honestly this is really unnecessary as if the hot and neutral have broke, what current is there to ground?

The ground prong being the last to lose connection means it will not lose connection while the others a plugged in. In the reverse case, where it is the first to loss connection, it will lose connection while there is something to ground.

> Another reason is a lot of manufactures of grounded/polarized wall-warts and GFI plugs tended to orient the damn things for ground pin down making ground up installs prone to falling out.

I've taken to using these kinds of 30cm / "1 foot extension cords" just to get wall worts a bit of distance away:

* https://www.amazon.com/dp/B00F1CLF7O/

* https://www.startech.com/en-us/cables/computer-power/externa...

Ditto - these are super cheap and super helpful.

Agreed: I invested in a bunch of the Monoprice version a few years ago. 1.59USD today (+ S & H).

* https://www.monoprice.com/product?p_id=5296

What do you think about the UK G plug?

Don't step on one that's upturned. Worse than Lego.

No real experience with using the design but it appears a bit bulky vs the others mentioned (was it to double as a medieval weapon?). Though I like the UK's idea of putting the fuse in the plug.

> Though honestly this is really unnecessary as if the hot and neutral have broke, what current is there to ground?

There could be stored charge in capacitors as in older TV sets or switching power supplies. Theoretically I suppose a short to one of these could energize other metallic components and would be immediately discharged if the ground is still connected.

It's super common in hospitals.

Also useful if you are using metal cover plates, as the author did, because if the plate falls off, it won't as easily short hot to something else.

It’s also a consequence of really poor American outlet design.

It’s not uncommon in other countries for the plug to be designed in such a way that by the time conductive surfaces are exposed, then the plug is far enough out that it’s no longer live. There are a few ways to accomplish this, either from recessed plugs to requiring that the exposed conductors be half coated in an insulator so that the first part exposed as the plug is removed is non-conductive.

Overall I like what you're doing here - power distribution in a typical home is less modular and extensive than I would like and this is a good step in that direction.

I don't think the extension cords are a problem because they're not in the wall (and I see actual Romex used in the wall).

However, I would take the time to carefully research exactly what pieces of this are, and are not, code compliant. Not because you need to redo it, necessarily, but because it is a very impactful way to learn these things and learn deeper concepts of safety and failure behind the rules. Nothing stays as well learned, or remembered, as details relating to work you have actually done.

It's also good to know what's not to code so that you can fix it before you sell.

This is an excellent point.

A lot of lessons learned, hard lessons learned (like fire, expensive equipment damage, injuries and blindness, and big sparks) have happened to get electrical code to where it is.

I'd have upgraded the recessed UPS outlets (inlets?) to be twist-lock style, something like this[1] for a more semi-permanent connection:

[1] https://www.leviton.com/en/products/3325-c

Then you don't have to worry about a "tight fit" or something dislodging (or half-dislodging) the plug.

Don’t those plugs mean something though? Like a specific Amp/voltage level? Or can you use this anywhere?

I’ve only used it for specific Amp/voltage required situations (UPSs actually).

They all mean something. For every straight blade there's generally an equivalent twist lock.

https://en.wikipedia.org/wiki/NEMA_connector#/media/File:NEM...

Yep, which is why I linked the one specifically for 20A 125/250V, IIRC that matches the OP's use case.

Surprisingly, there is no physical shape (that I'm aware of) to distinguish between 120V and 240V, it's up to the user to be aware of possibility of alternate voltages. I have seen color schemes used to distinguish voltages.

Orientation of the blades. The NEMA 2-15 for 240v 15a has both blades horizontal instead of vertical like a normal 120v 1-15 plug.

You can get l6-30p inlets. Appears to be common for RV use.

One suggestion, use a differently colored outlet for the sockets served by the UPS. This to avoid anyone else mistakenly using them for something else.

Another alternative would be to use Lutron's Claro AC outlets designed for dimmable control. They've got a smaller prong for the hot leg.

I have some sockets for outdoor holiday lighting that I've colored to avoid mis-using them for anything else.

Its very unlickely anything would be plugged in here, the outlets are located under desks, behind TV's etc. They are also the only decora 15a outlets in the house, everything I do new is 20a, so you'll identify them pretty easy

You will, but that distinction will be lost on others.

Who else is in my house?

Are you planning to live there forever?

For some time I am looking at a home built UPS to power my entire house; not buying an UPS, but building an UPS from a few packs of LiFePO4 batteries (probably in series to 48V) and an inverter. This kind of setup can be built with regular lead acid batteries too, very cheap, but the battery life is a lot worse than LiFePO4. A 4kW inverter can power my entire house, I live in Europe and we don't use dryers here, I think they are the biggest electrical consumer in a typical US house. The utility link is limited to 4.5kW anyways, so I don't lose much.

The whole point is I can easily expand in the future to charge from a solar panel array; solar panels are cheaper and cheaper, the biggest cost is the batteries and installation. Until then, the batteries can be charged from the utility company and the efficiency is close to an APC Smart UPS.

Looks very cool!

Seeing the limitation in how many of the UPS sockets can be used, I'd say it's a little bit of a shame not to have used high amperage IEC connectors - e.g. C19/C20 ones.

Most UPSes have options to work with these natively rather than having country-specific and often painfully shaped connectors (e.g. UK sockets are huge!)

Why did you take this approach rather than getting a hardwired UPS and installing a subpanel?

A subpanel would make future expansion easier.

I agree with this. You can get a kit [1] to hardwire a UPS. You could then take the output of the UPS and run it into a subpanel with a separate 15 amp breaker for each room. That way you won't have extension cords, etc. which might only be rated for 15 amps drawing 30+ and potentially starting a fire.

1- https://download.schneider-electric.com/files?p_File_Name=AS...

> There are several points here that probably don't comply with code. The fact that an extension cord has been brought into a permanent circuit is probably one of them.

If you wanted to do this up to code, how would you do it?

For starters, when I looked into doing this I found everyone disagreeing if it was code. I personally think it might be up to code actually

If they sell those power inlets which are NEC approved, how can you use them without breaking code? So it MUST be code. But then you ask 10 people and get 10 answers

There are larger UPS's designed for hard-wiring, but they are almost always VERY large. I think that might be the only way to avoid an inlet cord like this

Its definitely not up to code, but that is not really a problem unless you plan to do a larger (permitted) project in the future or when you sell the house and are getting it inspected. The one thing to watch out for is that if your house does burn down (presumably due to reasons not related specifically to the non-code-compliant wiring) the insurance company will try likely try to deny your claim.

At least in my jurisdiction (America) the only way to achieve what you are trying to achieve is by installing a dedicated subpanel fed by the UPS with appropriate breakers. I believe that such an installation would only be code compliant with a UPS that was designed for such an application (with a hard wired output connection, and appropriately designed disconnects), but a lenient inspector might let you get away with feeding a subpanel from an extension cord as long as as of the breakers and capacity factors work out correctly and the grounding meets code.

The biggest issue I see is that the system is not labeled correctly (at all?). That is a pretty serious issue because if, for example, an emergency worker were to come into the house under the expectation that the power to the house was cut (at the service disconnect) but the house would have live outlets that are otherwise unmarked. See https://www.mikeholt.com/download.php?file=PDF/11_Generators... for more information (the relevant section for your system starts at page 16)

As other commenters have pointed out, just because you can buy something that says NEC approved on the sticker does not mean that it is approved for your application. A good example mentioned elsewhere is using a 16awg SJTW extension cord to power a 15a load--all of the connectors will plug together but the combined solution is obviously not code compliant and even if it doesn't melt/catch fire it will not supply the load with clean power.

Electrical code is complex, but more importantly there is not one unified electrical code. Your municipal, county, or state government determines what the electrical code is in your location. Usually it will be the National Electrical Code (NEC) but inclusion, but probably an older version, and then most governments have implemented various changes on top of that.

So the first question to answer is what NEC allows, but you will then need to double-check for your specific context.

Further, the power inlets are NEC approved but that in no way means that they are approved for this use. I'm far from an expert on the NEC but I can pretty confidently assert that it allows such inlets only for specific uses, and you would need to check carefully that what you propose is one of those uses. A very rough rule of thumb is that you are not normally allowed to have more than one "user-removable plug" on the path to a device. There are a number of exceptions to this, but any time you're plugging into something that plugs into something else, you need to check carefully if what you're doing is allowed.

I think the biggest problem is that an energized in-wall circuit must have an upstream circuit breaker. His new circuits do not, and rely on the source power supply being connected to a breaker. Because the power supply is a UPS, turning all the breakers off will not cut power to that circuit.

The UPS does have breakers though

A breaker panel isn't just used for overcurrent protection, though—it's also a standard point to disconnect power when needed. The possibility of house wiring being energized even when all power to the house is cut is dangerous for anyone not familiar with the setup. This could be lethal if work needs to be done on it and OP isn't around to explain how it's wired up.

True, but signs that there is more than on disconnect are common in industrial settings. They are rare in house situations, but putting a sign on the main breaker box is probably enough to meet code. Though it would surprise the inspector.

This is common in home systems where you have a second power source like solar. Mine has markings like this: https://www.jadelearning.com/blog/pv-system-marking-and-labe...

This is the problem. You cannot rely on the circuit interruption capabilities of whatever devices happen to be installed on that circuit at a given point in time. If these were permanently installed, you might have an argument that it is passable.

The situation that is dangerous here is if a power source were to be connected to one of these inlets and it did not have a sufficiently-sized breaker and the other side has a dead short, you are looking at a fire inside your walls.

I just installed a 50 amp generator inlet on my main panel, and even though my generator has a matching 50 amp circuit breaker, I installed a separate matching 2-pole 50a breaker on the inlet circuit. This protects the electrical system from even the most screwed up of generators being connected to the panel.

Surely that could be said for anything though? There is nothing stopping me from getting an adapter to plug a space heater with a cheap 16awg cord with an adapter into a 30a outlet

Here there is a breaker, and if the UPS is disconnected, there is no power. Of course someone could go and plug this into a 30a outlet, however that's something that I wouldn't do, so its not really my issue

>There is nothing stopping me from getting an adapter to plug a space heater with a cheap 16awg cord with an adapter into a 30a outlet

That would be against code.

There's nothing stopping you from running bare wire through your walls.

There's nothing stopping you from not bothering to ground any outlets.

There's nothing stopping you from using 14AWG romex on a 50 amp breaker.

Etc., Etc.

All of that is against code, and I've personally seen all of that in the wild at people's homes, offices, etc.

If you wanted to do things the #rightway, you'd most likely need a subpanel for the UPS to feed.

In the case of a cheap 16awg cord, yes you have created a dangerous situation, but it is not one that is considered part of a larger structure in terms of code. This is the electrical equivalent of spraying gasoline around at the gas station and acting surprised when it turns out poorly for everyone.

> however that's something that I wouldn't do, so its not really my issue

Electrical code is designed so that even an incompetent operator cannot produce a dangerous situation inside a building's electrical system. OSHA, USCSB, et. al. would be the first to tell you that relying on a specific individual to interlock a dangerous situation can result in extremely adverse outcomes.

I agree with this, and adding a breaker between the UPS and load is probably the solution. The trouble is many UPS units have a set of controlled output banks and the ideal solution is extending controlled output to the wall breakers downstream of the UPS.

NEC 400.7(A) Flexible Cords point 11 would seem to allow it so long as it was 1-to-1 inlet to outlet.

Flexible cords and cables shall be used only for the following...(11) Between an existing receptacle outlet and an inlet, where the inlet provides power to an additional single receptacle outlet. The wiring interconnecting [...] shall be a Chapter 3 wiring method. [...]

I don't know what Chapter 3 is though, and in the below study guide link it seems to show a double outlet in the graphic.

https://www.electricallicenserenewal.com/Electrical-Continui...

Thanks for digging that up, it looks like I am actually golden then

thats old code, nec is now 2020. i dont have an nec codebook...but pretty sure you cant use extension cord connected to the ups connected to another receptacle...the section of the relevant code would be labeled something like 'uses not permitted.'

the code you referenced states 'Between an existing receptacle outlet and an inlet'

the circuit is also unlikely to be arc fault protected, which would mostly likely be required.

also how the romex is run, is not to code.

No matter how much better some things might be, it's whether it's in the code or not that dictates if your house wouldn't pass an inspection.

One of the things I think would be most likely to throw up a red flag and immediate fail would be the "suicide plugs".

Even though they're not energized (but rather, used to deliver power to the remote end), most electricians and inspectors wouldn't sit around waiting for you to explain your brilliant power delivery scheme.

The only real way to do this stuff code-compliant would be to purchase and install a real hard-wired UPS system, use properly-installed Romex (or other suitable code-compliant wiring), and get things inspected by the local authorities.

Usually if it's not installed by a licensed electrician, the inspectors will be even more stringent.

Those plugs are legal, and commonly installed for generators. The only part the inspector sould question is why they are not connected to a breaker to protect the wiring.

I was wondering if those would require an ED of some sort in line of sight.

I was wondering if those would require an ED of some sort in line of sight. I know that permanently wired things like HVAC or Water heaters do, but I've never read up on that sort of connector.

Those are not suicide plugs and what is there is code compliant.

Suicide plugs refers to extension cords which have been built (or modified) so they are male/male. One in which the far end will be exposed while energized. In this system, the male plugs will never be energized while exposed.

I understand that, what I'm saying is you'll have to spend some time explaining to the inspector how this system works, and they'll give an immediate fail (unless they're pretty lax—I know in the midwest they are not) unless you're a licensed electrician.

Mostly because 'sparkies' often wire things up like this and use random extension cords in walls and create fun fire hazards.

I agree that the installation is in 'the spirit of the code', but there are enough little variances that I would take a bet that a random inspector would not pass it on first glance.

Live in Midwest. Current home had an exemption cord running in a ceiling through a hole drilled to outside powering a light. My inspector said it was “interesting” and could cut and cap the cord if I was worried.

Not sure where all this worry of code when selling a house comes from. Code changes. No 20 year old house is up to current code, doesn’t mean you can’t sell it.

For starters, you'd secure those NM cables within 8 inches of exiting those plastic boxes, or you'd secure them to the box with a clamp and secure them within 12 inches of the box exit.

After the author began the article by whining about the previous owner's outlet wiring, I expected better attention to detail.

Fished cables do not have that requirement

Depending on the rules of your jurisdiction having authority (JHA) it may not be possible for you, as a homeowner, to install such a system in a code complaint way. This will definitely require a permit. Most JHAs make some allowance for homeowners to be permitted to pull permits for work on their own home, but there are usually pretty strict limits on what these permits would cover and I think most JHAs would require that permits for a central UPS be obtained by a licensed electrician.

And as mentioned elsewhere, I doubt the JHA or the manufacturer of the UPS would approve of this kind of installation. There are UPS specifically manufactured for a hardwire installation and that's what ought to be used here. That said, I am sympathetic, because UPS can become very expensive very fast. I'm balking at the cost of 2U rack models from Eaton, he will have had to shell out a good chunk more based on his VA requirements but at least he avoided the significant premium for hardwired.

I have a multi room UPS!

It's called 2x Tesla Powerwalls and a 7.5Kw solar system! :-)

Do you have it setup to work if you lose grid connection? It seems like most solar/powerwall systems are not setup with appropriate disconnects and so must be designed to not work with the grid down. Seems like a big waste.

I wonder how much money utilities could save if everyone had a big in-home UPS/Solar and 99% or 95% grid reliability were acceptable.

I just finished installing my own 6.6kW system. From my research, we're not at the point yet where an inverter that can be (a) grid-tied and (b) charging batteries will be as reliable as one that does either (a) or (b) (but not both).

They do exist, however, and hopefull they will get better over time. This will allow more people to add a moderately sized battery system to a grid-tied system, and then we end up with the best of all possible worlds (or something much closer to it).

There are also grid-tied inverters that will provide limited online power even with the grid down. These also seem to be not as reliable as the "grid down? i'm down" design.

The really tricky part is that for the inverter's output to be instantly switchable with the grid, it has to be phase aligned with it, and so the inverter has to see the grid phase and match it.

I just read your previous blog on Backup and noticed that your choice of 1000-year DVD and its manufacturer.

They’ve gone 403.

https://web.archive.org/web/20140325203319/http://www.mdisc....

https://en.m.wikipedia.org/wiki/M-DISC

That's very cool. I love the idea of doing extension cords + inlets. I've been thinking about how to wire my big TV to my UPS, that's a very clean way of doing it.

What are use cases for power inlets?

Also, are they hot if nothing is plugged in?

Inlets are for putting power into something, just like an outlet is for getting power out.

They are reversed from an outlet because don't ever want the hot part to be exposed.

Main use is a backup generator. Your electrical panel is supposed to have an interlock so you can get power from either than inlet, or from the power company but never both. When the power goes up you plug your generator in, flip a switch and your house has power. Legal and fairly common.

Great guide I hope you do more in the future!

Thanks, I'll keep posting anything I think is interesting

Definitely dislike seeing the various code violations, but definitely enjoy the get it done attitude and the results!

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