Wiring a Step-Down Transformer for a Power Feed

Today we're finally getting around to wiring up a transformer to power my 120V mill power feed from a 240V circuit. It's about time.
Tools used in this video:
*This site contains affiliate links for which I may be compensated
Hammond 250VA Control Transformer (*eBay): ebay.us/ANTCkS
Hammond Control Transformer Fuse Kit (*eBay): ebay.us/e9ygh5
Engineers Computation Pad (Amazon*): amzn.to/3EKFZ9o
Milwaukee Fastback Folding Knife (Amazon*): amzn.to/3F4Ujs8
Wera Kraftform Screwdriver Set (Amazon*): amzn.to/2UzK6CL
Hammond 8x8x6in Junction Box (Amazon*): amzn.to/3f8F5rG
Knipex Automatic Wire Stripper (Amazon*): amzn.to/3aFM8oF
AM-10 Pneumatic Crimping Tool (Amazon*): amzn.to/3qZ52iV
Ferrule Crimper Kit (Amazon*): amzn.to/30hUfAQ
Wago 12AWG lever nut assortment (Amazon*): amzn.to/3hPMwFE
Fluke 375 FC True-RMS Clamp Meter (Amazon*): amzn.to/3C6aeoW
Raw Kevin MacLeod (incompetech.com)
Licensed under Creative Commons: By Attribution 3.0 License
creativecommons...

[@Clough42]

Common questions: 1) Why didn't you run a neutral? This would require well over $100 worth of copper and a lot of work to replace cable in finished stud walls. 2) Why did you wire four outlets? There will eventually be three power feeds plus the DRO. 3) Shouldn't the white wire on the 240V input be black? Yes. It's common to color it black with a marker. I need to go back and do this.

[@maxheadflow]

I assume question 1 was the response to adding a neutral as apposed to building the neutral in on the original install? Question 2. Can't have too many outlets.

[@Clough42]

@@maxheadflow ahh... Yes. Including it 20 years ago would have been great. Copper was way cheaper then, too.

[@georgel5308]

3. Electricity is color blind don’t worry about colors

[@Oberkaptain]

James, why not mount the box to the side of the mill?

[@VoidedWarranty]

At some point in the future I'd forget and plug a shop vac in there and ruin my day. Resettable circuit breaker on the output?

[@billstrahan4791]

For some reason this brought back memories of when I worked on drilling rigs. I still touch stuff with the back of my hand when I'm uncertain about the electrical situation of something. When I'm not confident in what I've wired up, it's still my habit to start with back of hand before grabbing it, just to stack the deck in my favor. :)

[@billcahill4218]

James, I'm a controls engineer by trade and I'm impressed. This is just how we create control power in our three-phase motor panels. Sometimes I need a lot of 120V and spec out a larger external mount transformer, but when I need to add a convenience outlet for a programming laptop outlet, this is exactly what we use. Automation Direct is a great source for things of this nature.

[@Clough42]

Thanks! I order from Automation Direct a couple of times a month. :)

[@donkinzer5718]

I suppose that you chose the 20 amp rated outlets because they had the connection type that you wanted. Otherwise, it's certainly overkill as 15 amp outlets would have served perfectly well.

[@tonyurquhart8278]

"Of course not, that's silly... I did the project just to justify buying the Crimper"! Hahah!!! How many times have I done that too... I love your style James... Oh - & your content :) On a serious note, watching you & a few other workshop guys in the US, makes me sooo grateful for our power standards here in Australia. We have 240V single phase or 415V 3 phase (yes some other occasional setups which are different, but generally speaking). So you basically have 2 choices Single or 3 Phase. It's so much simpler.

[@scottl8457]

James, I liked the setup with the transformer and the outlets. My concern would be: what happens if you have to emergency stop the mill? The table will continue to move. When I did this for my mill, I pulled the 240v power after the contractor in the mill control panel, so the table would stop moving if I estopped the mill. I also understand there may be warranty implications, but I also worry about safety. Just a thought....

[@Clough42]

This mill has a motor switch. It has no ESTOP or contactor.

[@rdnybowersox]

You never cease to amaze me with some specialty tool that you pull out- i.e. wire crimper

[@Clough42]

I bought it for another project that will require a couple hundred crimps.

[@nand4011]

Aside from the excellent content of your videos, it has been impressive to see how much more skilled at editing and comfortable in front of the camera you've become. Many channels have trouble finding the balance between detail and respecting the viewer's time, and your effort really shows.

[@David-qd3ff]

“I’m not an electrician/expert” you crack me up. You’ve forgotten more things than I ever hope to know. You are one of the most analytical and detailed people I have ever encountered. Elon Musk should be afraid of you.

[@MrCurstesy]

Nice vid. Just a suggestion-- it's bad practice to shoot a tech screw into a box. Having the sharp edge can cut your hands and your conductors. Use the appropriate length screw and put a nut on the inside (even having threads exposed is considered bad practice, over the years the exposed threads can wear through insulation, especially if the conductors move ( a flex run into a motor, etc.)

[@samvoelkel2046]

This is a great little project that shows the "right way" of handling this simple job. Well done, as usual.

[@chucksmalfus9623]

Hi James, I have 2 small issues, I know how much you love criticism…lol . I usually when grounding the neutral on the transformer use the green wire from the neutral term to the ground so just looking at the transformer it’s obvious that the neutral is grounded instead of having to see where the second white wire is going. I realize in your panel it’s easy to see but in more complicated panels it’s not as easy. Also with only a 250 va having 4 outlets might be tempting to overload it and blow the fuse.

[@Clough42]

Yeah, I think using a green wire here would be clearer. I was thinking about panels I've seen where white and bare wires go to a common bus bar. I plan to eventually use all four outlets.

[@brucetuckey7909]

James, Good job done your way I am not going to comment on the how because you did what is rite for your shop. I would do what I see as rite for my shop. Everyone else will try to blow smoke where they don't really know.

[@David_Best]

Leviton should consider making a wireless neutral terminal box. With WiFi and an iPhone app to control it. 😃

[@v8Mercury]

Great video. Thank you. This afternoon I'm going to go and check what I did with the neutral when wiring my 440v 3ph lathe. I was so excited about the lathe I don't quite remember the wiring. 😀

[@derbrett1503]

Hi James, really appreciate your projects, planning, execution, reflections and the extended effort to document for us all. Thank you for creating and maintaining the blog summary as first post. Bringing the gems to the top. Your viewers make some great contributions and normally we all have to mine for them or mostly, give up. and lose the opportunity of extended valuable input. Regards, Brett

[@DAKOTANSHELBY]

Great work James! Love it when you introduce another new tool - an automated crimper.

[@624Dudley]

I admire your standards of workmanship, James. BTW, I have a similar drive motor that has the annoying property of traveling at different speeds, with the same setting, depending on direction. I’d sure like to improve that. (I think Quinn mentioned it in a past video) Have you seen this?

[@Clough42]

I saw her video. I haven't observed that in the Align feed. I haven't paid very close attention, though.

[@georgel5308]

As an electrician great job. Good demo and lessons. Also great execution

[@grahameida7163]

So my only silly question is, why didn’t you just get a 240v power feed in the first place? 🤣

[@Clough42]

Are they available? I didn't see that as an option.

[@grahameida7163]

@@Clough42 yep, well we have 240v versions in the uk, so I presume they are…

[@КонстантинКучер-щ5м]

You can make a square hole in big box and put a receptacles on it. More of work, but much cleaner look at the end.

[@steveclark2342]

Really like your transformer controller build. I also have a PM-935. Your build of materials list didn't include info on the fuses; part no, where purchased. Please, would you share those details?

[@chrisarmstrong8198]

Are you concerned about rogue metal swarf particles (the natural enemies of electrical insulation) getting into the open receptacles?

[@AmateurRedneckWorkshop]

Well done as usual enjoyed the video. Sitting up there in the cold dry north corrosion free while all of us in the humid south rust.

[@Clough42]

Yeah. It's a burden, to be sure.

[@_mylastname]

A MILLION THANKS!!! 🙏 OH MAN, SERIOUSLY, THANK YOU!! GOD BLESS YOU & ALL!

[@marktheunitedstatescitezen185]

Question, I have a 5KW 230v inverter charge controller 48v , what’s you’re thought’s me using a 100A MTO Transformer 220-440 inlet & 110-120 output for a house inverter for emergency use only my battery banks are lithium phosphate 3.2v 280Ah feeding the inverter ?

[@hannahkaranja8113]

What is the spec for the fuses you used on this project. FYI hubby installed it for our setup in Kenya so am able to use 110 tools like sanders, jigsaw etc. what I haven’t been able to use is my compound sliding saw or table saw. We have a Bussmann Fuse Current Limiting, Dual Element Time Delay, Midget Cartridge, Time Delay 2 Amp 250 V 13 and a 15 Amp but neither works for the saw. Is this the wrong fuse?

[@maxcactus7]

15:03 "The funniest part is, you can't tell if that's a joke." Au contraire! I'm not falling for this trick. You gave us the answer a couple weekends ago. To quote "The other reason I wanted it is because it's a tool and I want to own them all" You are the man I perspire to be! 😁

[@mumblbeebee6546]

As always you explained it calmly and thoroughly and yet I was feeling entertained, not lectured. Congratulations to finishing the project ;) Self tappers protruding into a box of electricity would not be my ideal scenario, but since it is your home shop, all good!

[@MrFrAnCk_]

"I didn't buy this tool just for that project, that's silly. I did this project to justify buying this tool." 😂🤷‍♂

[@smithlevenson1]

All the holes in my wall will attest to my default of running new wires. This takes a brain like yours to figure out and will probably be very useful knowledge for later.

[@tonysmith7554]

I want to power a single-story house 3bed two bath 120volt on each leg. what size fuses what I use for this 250va transformer ?I live in California,

[@HexenzirkelZuluhed]

It's okay to remind us, to start doing those things we intended to do at some point. But good to see, that even someone as organized as you does procrastinate a little sometimes.

[@Clough42]

A little?

[@Dwarfracer88]

Did you consider running a neutral to the mill? Or was that beyond feasible?

[@Clough42]

Feasible, but expensive. I would need to replace the entire circuit with 10-3 NM-B.

[@tmartin6717]

Always enjoy your work, This Old James.

[@joannepfeiffer977]

Great video, You might want to protect your box there on the floor. The shop that I work in had the same set up . The problem is metal chips down on the floor. You can imagine what happen. Drilling chips make a interesting moment.

[@quadmasta]

Seconded. 2-gang in-use covers are cheap insurance

[@joewebb4836]

Separately derived system, bond at neutral (like you are).

[@russterman1]

I Have Too Many Tools!! (Said No One Ever);-)

[@joshuahuman1]

Great video I didn’t know you could do this. I need to do this to my cnc conversion that currently uses a 240v plug for the spindle and a 120v plug for the control/steppers

[@Clough42]

The exact power requirements of the control will dictate whether this is an economical solution.

[@LordPhobos6502]

Great job (as always), very neat and professional looking. Silly question... was there not a 240v powerfeed model available? Or would that have been more hassel than it's worth?

[@Clough42]

I haven't seen a 240V model. I would think they would exist.

[@floxmfpv5295]

Great video... as always, but I was just wondering what happend to the pm-940

[@Clough42]

It's a sad story. It didn't work out between us.

[@Th3Su8]

I really only have one issue with the way you had done this. You left the possibility of plugging in other devices at the same time as the power feed motor. I personally would have used what is called a simplex receptacle connected to the small transformer so only one thing can plug into it. This way you do not possibly overload the transformer and have to replace fuses. What you did is fine and obviously works, it is just that this is on the internet and I have to point out that I would have done it differently. You did do a fine job, as usual, to keep the installation nice and clean.

[@Clough42]

There will eventually be three power feeds and the DRO.

[@crichtonbruce4329]

Great post James (as usual). As the unit is shoved under the mill on a bare cement floor I suggest you put some rubber feet on it to prevent rust or a short if the floor gets overly wet. I had a brief fantasy of you cutting a big hole in the side of the mill casting to mount the box in, but that would be way too much work.

[@Clough42]

There is such a hole and panel already, but that's where the flood coolant sump is located, and I may use that some day, so the humidity in there will be around 100%.

[@jonathanrubio5837]

Could I use this to go from 120 to 240?

[@drewdunny5]

You need to bond the box to the other grounds in the wego.

[@donteeple6124]

Nice job again James !!! Neat, concise, and no nonsense.

[@rich1351]

The part about buying the crimper to do the job or doing the job to justify the crimper is the reason I own most of my tools

[@624Dudley]

It’s fair.

[@sureliaketan]

Dear jsmes I've been ordered ELS through ebay.... Like to know how to set with my own Lathe Machine... Can you please help me out to install the software....?

[@Clough42]

There's a whole series of videos, and documentation on GitHub.

[@davidteitelman3890]

Transformers high primary/feed sides are identified with the letter X, & the low secondary/load sides are identified by the letter Y. Not sure how you did this. Also: The primary side would have 240V (twice the voltage ... by a SERIES connected across the entire winding. Then the secondary would be stepped down (in half) to 110V by tapping the middle of the winding ... which serves as the neutral to both short 110V windings. You some how made it work by placing the neutral connection to the hot side of just 1 of the secondary windings !!! 🤔

[@Clough42]

I think you're confused because you're assuming this is a 120/240 to 120/240 transformer. It's a 240/480 to 120/240, so both primaries are connected in parallel (240V), and both secondaries are connected in parallel (120V). I showed the jumpers installed directly on the terminals at around 7:58.

[@jfl-mw8rp]

Why not use a step down voltage converter like one you would use in Europe with USA appliances. A 1.5 to 2 KW should work?

[@Clough42]

I've always been very suspicious of those. They come with copious warnings to only use them with hair dryers and not anything electronic. I assume (but don't know for sure) that they're doing something unsavory, like using a diode to cut the total power (but not the voltage).

[@tonysmith7554]

completely off grid.

[@David_Best]

So you did this project to justify the crimper. Did you also forgo pulling a neutral to the mill to justify the buying the transformer, enclosure, et al? 🤔

[@tadamb1]

Oh, come on. Just use one hot leg and use the ground as a neutral. What are you, chicken? It'll be fine. They wind up in the same place anyway.

[@Clough42]

It'll be fine until it isn't. Thinking about adding flood coolant to a system without a safety ground...

[@ceasardr7312]

nice work, a further safety step is that you can put the box on some feet (plastic or rubber) for elevation just in case of a liquid spillage on the floor (for whatever reason) especially that it is there on the ground with no direct line of vision. wish u all the best

[@paulmcewen7384]

Very interesting video. I have seen dozens of 120/24V control transformer systems with the neutral of the 24V secondary bonded. I have not to my knowledge worked on a 240/120 control transformer with the secondary bonded as shown in this video, but it should be the same in principal. Will have to dig a bit deeper next time I see it (same should apply for three phase equipment with control xfrmers).

[@henrikskott]

For me, that would not be a joke. It would be funny because it's true. And also because it's an conscious choice, not an impulse. Nowadays, at least. Or so I tell myself...

[@thebotformalityknownasdale2564]

Im going to build a mill and I'm converting a radial arm saw the motor is no good it only runs at 5000 rpm so I need to replace with a motor that I can control the rpm but I'm not shut what type I need either a stepper or what? could you give me some help with that and where I might be able to get it from?

[@Clough42]

You're converting a radial arm saw into a mill? That sounds ambitious.

[@javiergarciaquiroga7169]

Great video, thanks! Could you comment on which type of fuses did you use, and maybe provide an affiliate link?

[@jescheffler]

James, this would have been helpful last month when I was installing exactly the same transformer on my mill :-D Thinking for yourself is overrated.

[@user-tr9wq6fe9k]

Howdy from Texas James, my question has nothing to do with the electrical but the square tubes under your mill. Did you find the table height just a bit to low so hence the additional height? If so what was the increase in height. Looks like 4" or so. Thanks

[@lwilton]

I don't know how much digging around you had to do to source all the parts, but boxes, control transformers, and at least some of the wiring bits are easily available form Automation Direct, and they often have 2 day shipping. The prices are reasonable too, and you know you are getting genuine stuff. I'm a little concerned about plugs on the floor. In my experience that is where they get wet, oily, and full of chips swept up or blown around on the floor.

[@Clough42]

Yeah, Automation Direct is great.

[@stephaneaudette6665]

Thank you very much, you're video really help me. Verry great explanation.

[@CapnCrusty]

I had a similar problem in my shop, but I opted to buy a $27 voltage converter which came in a metal case with plugs, a switch, indicators and a fuse ready to go.

[@cnyjody9650]

Great video! Last week I installed a new plug on my jigsaw, now it runs backwards:')

[@staciedziedzic8706]

Hi James! Very interesting but cool! I don’t understand a lot of the stuff that you were talking about but a great video nonetheless! Take care!

[@pedroveloso9707]

hi, just to ad that kind of transformers is use to, in electronics bench, as a isolation transformer (1:1), we do not connect ground, it must remain in a separate plain, very Andy in to connect oscilloscope to boards, no ground loop. :) cheers.

[@Dezeberbro]

I was in a situation where our control transformer was not giving us the correct output so what we did was connect out x2 to the panel neutral and then we bonded it to ground

[@Clough42]

You bonded the panel neutral to ground at a second point? Eek.

[@flameboy7265]

Informative as always James but did you get a copyright license from ToT to use your hands this way?

[@chuethao385]

Why is your Primary in parallel it be in series there should only be a jumper on your h2 and h3

[@Clough42]

Because I'm running it on 240V. You would wire the primary in series for 480V.

[@jeremycable51]

I’m no electrician by any means I know jack about it but am I nuts to think that now that box is live to ground when you run anything 110 from that outlet?

[@TerryPullen]

This would have been a great opportunity to build a custom metal enclosure that held the transformer and outlets.

[@jhawker2895]

Another very well presented video .... Thanks for sharing ... Stay safe...

[@kenjames6172]

Off subject why the risers ? how tall? did you do a video?

[@Clough42]

They add 4", putting it at about the right height for me to use comfortably. It's just two pieces of 4x6x3/8"-wall rectangular tube with holes drilled in it to anxhor the mill and to mount the feet.

[@RRINTHESHOP]

well done.

[@David-qd3ff]

He who dies with the most tools wins, you are quickly getting close to the lead.

[@janetrodriguez4567]

Nice🙂

[@joeldriver381]

Well 💩. Now I need a pneumatic crimper.

[@nickconway3219]

Thank you very good explanation

[@tmurray1972]

Good job James, and you have a really awesome set-up there.👏🏻👏🏻👌🏻

[@chevyfahrer]

15:01 don`t see the joke,thats how i plan all of my projects

[@cdrive5757]

40 years ago when my shop was built as an extension on the rear of my home I ran the 240V mains in conduit and left a pull cord in the conduit. All additions I've made since then I always made sure I left behind spare pull cord. It sure beats having to dig out my wire snake when additions were made. On that note I can't imagine doing the original pull and deciding to save a buck by eliminating the 120V neutral. Not in this life! Wakodahatchee Chris (WA2ERQ)

[@Clough42]

Conduit would make the job much easier after the fact. The original run was with 10/2 NMB. Clearly if I did it again, I'd use 10/3 and run a neutral.

[@tadlaird8843]

I guess this is a stupid question, but why not just plug in an extension cord to a 110v outlet, and run your 110v accessories off that? The only reason I can imagine is wanting the 110v circuit to be coupled to the 240v circuit so the 110v drops if you lose 240v, but wouldn’t a magnetic relay take care of that?

[@Clough42]

I don't want an extension cord draped across the shop.

[@maxheadflow]

It's been a while since I've done any transformer supplies but since transformers are primarily inductive devices they wont have in-rush current. it's typically the load on the output that cause the in-rush current. There maybe a very small amount of current from capacitive coupling but I'd expect it to be very,, very low.

[@Clough42]

The Internet disagrees. en.m.wikipedia.org/wiki/Inrush_current "When a transformer is first energized, a transient current up to 10 to 15 times larger than the rated transformer current can flow for several cycles. Toroidal transformers, using less copper for the same power handling, can have up to 60 times inrush to running current."

[@gregfeneis609]

Thumbs up. I'm wondering if it could go easier if you had mounted the transformer on the "lid" panel, wired it up and then covered the works with the box 🤔

[@Clough42]

You could do this, but I think the other drawbacks outweigh the benefits, since the wiring entry and exit are all in the box.

[@truehybridx1]

So why would you do this vs running a separate 120v circuit from your panel?

[@Clough42]

Wire, time, closed walls, full panel. The manual for the power feed specified it for this situation.

[@jzrgrmm]

I've found that some equipment have internal transformers with more than one input option. But then yes, you'll probably void the warranty.

[@Clough42]

Good tip. I just re-checked the circuit diagram, and I don't think this one has a multi-tap transformer in it. In fact, the manual actually calls for an external control transformer for operating on high-voltage mills.

[@janusznowak8124]

Hi Clough I’m always looking forward to watch your videos. You usually have good explanation and reasoning for the decisions you make during the project. This time you skipped the part why you decided to connect the one secondary to the ground. The transformer you installed works also like safety transformer, until you ground one terminal. The grounding doesn’t increase safety - it decreases. That’s why in difficult situations you use safety transformer. If one secondary wire will short to metal part of the machine you will have the same case as you deliberately did. You are quite smart and I expected that it is some reason you did this. Thanks

[@Clough42]

Watch the video again. I explained it in detail. It's required by code because without bonding the neutral, there is no way for a fault current to re-enter the circuit to blow the fuse.

[@sumduma55]

So what kind of power consumption does a transformation like this use when idle? I assume it will be lower without a load on it and increase as the load increases. But there will always be energy or current flowing on the primary side by the nature of how it work. Ot was thus explained in the video and I misses it somewhere?

[@lwilton]

In _theory_ an idle transformer that is correctly rated draws no power of it's own. In actuality it generates some small amount of heat and sound energy, so is consuming power. I'd guess that a transformer this size is probably using less than 5 watts, probably 2 watts or less.

[@transmitterguy478]

James, do what we do here in the sticks, just zip tie a white wire onto the conduit from your panel to your mill, hook it up and your good to go. LOL

[@Clough42]

The wires are in insulated walls, so there's nothing to zip tie to.

[@jimhunt5259]

Still have no idea how a transformer works..it's magic right.

[@planomustang1]

Not magic. Just Physics. Go get a college level Physics Book, then look at the Electricity and Magnetism chapters. Seriously, it is not that hard to understand how it all works. My dumbass was able to figure it out, at age 19. I bet you could understand it all, in less than a couple of weeks.

[@chevyfahrer]

20:00 did i get this right? there is no mechanical difference in the 120 and 240 Volt outlets as mechanical coding so you can accidently plug in to the wrong outlet?

[@Clough42]

No. The 120V outlets are NEMA 5-20 and have a vertical hot blade. The 240V outlets are NEMA 6-20 and have a horizontal hot blade. They aren't physically compatible.

[@jasonh3109]

Another great video!

[@UncleKennysPlace]

I put a little blob of hot glue in a nut driver to help it hold a nut for such jobs (I use it as a wedge, I don't glue in the nut.)

[@g.tucker8682]

Great tip, for when you have to hold the driver vertically. In this case, the quick n easy solution is simply to turn the box on its side.

[@NathanielHourt]

I like how you sprung for the 20A outlets on the 2A line. x-)

[@Clough42]

I explained why. Though lots of people seem to have comments about it.

[@MrZX1206]

I know you enjoy troll comments so here is one for you. In the last few seconds you say you are happy not to have a wire drug across the shop. The correct word is dragged. Drug is not the past tense of drag.

[@jerryking5195]

He draggededed across the floor according to my grandson

[@Clough42]

Using "drug" in this context is common in parts of the US, and is generally considered a feature of dialect. So... Is criticizing someone for their dialect a form of linguistic discrimination?

[@624Dudley]

@@Clough42 Well put, James.

[@EZ_shop]

Nice work. Ciao, Marco.

[@azenginerd9498]

Perhaps the other "lesson learned" is to run that neutral when installing the circuit even when you absolutely positively KNOW you won't need it... EVER... ahhh hindsight.

[@Clough42]

Yeah. The circuit is #10 solid, so I was also concerned about wrestling with another conductor in the boxes. In hindsight, I'd like to have the neutral.

[@mikemarriam]

So basically the transformer box is a sub-panel.

[@Clough42]

I don't know if it qualifies as a sub-panel, since it plugs into a receptacle.

[@mikemarriam]

@@Clough42 on second thought you don't ground and neutral in a sub-panel. It's like it's a second main panel.

[@Clough42]

@@mikemarriam I see where you're going with that, but I don't think the analogy is useful. This is a control transformer., and it requires a bonded neutral for safety.

[@monk1100]

Love the mill

[@sebastianuchman3145]

James, I am happy to see you using ferrules. IMHO one fuse on each side is enough. All fuses I saw datasheets of allow 40% over current for 30 minutes. In your case 2A fuse will conduct 2.8A without problems. This means in case of short on the secondary side, the transformer will probably never go up to this value and the fuse never blows. Anyways, nice clean job!

[@Clough42]

Since both 240V input wires are live with respect to ground, two fuses are required. A short to ground in the coil, for instance, requires protection on both hot legs.

[@sebastianuchman3145]

@@Clough42 I forgot that in the US 240V are between phases, so two fuses make sense. Thanks for the answer!