The Fresh Loaf

News & Information for Amateur Bakers and Artisan Bread Enthusiasts

Converting 3phase MIWE Condo to single phase for residential use

Moya Gray's picture
Moya Gray

Converting 3phase MIWE Condo to single phase for residential use

Hi All

I need advice.  I sell artisan loaves at the local farmers market.  I started off using my home oven but it took me 9-10 hours of continuous baking. then I broke the glass on the door and began to bake in a MIWE deck oven (2 decks) which cut my time way down.  The oven's owner is closing his shop and has given me the chance to buy it.

if I do buy it I would want to install it in my home because 1) I have photovoltaic panels and generate more power than we use so my power is almost free; 2) no landlord to pay; 3) I can bake non hazardous foods in my home and sell at the farmers markets legally; and 4) a cottage industry bill is moving through the legislature and hopefully will be law in one or two years.  Other background information:  as I live in hawaii it is next to impossible to get good used deck/steam ovens without paying huge shipping costs. there are probably only one or two other bakeries that have deck/steam ovens and they are competitors; the commercial kitchens that are rentable do not have deck/steam ovens. 

MY QUESTION:  the oven is three-phase, but my home is single phase. The manufacturer says the oven can be converted using a phase converter.  But posts on various sites say this may not be easy to do and that electricians may not want to do it.  DOES ANYONE HAVE EXPERIENCE WITH CONVERTING OR ADVICE FOR ME?

Thanks in advance!'s picture

I logged on to "report this" because it looked like yet another in the recent spate of TFL spams but...not!

Advice here is easy:  Enlist the services of a qualified electrician.  Full stop.


Moya Gray's picture
Moya Gray

Hi tom - haven't been here in about a year so haven't known about spam. Who is spamming?

I am looking for an electrician now, but wondered if anyone else has had this experience and if so, what they did regarding reluctant -to-help electricians 

fotomat1's picture

better off looking for a new oven. 3phase is commercial and to convert an appliance especially an oven would be dangerous. I have used phase converters on motors but the worst that can happen there is the motor not starting. Look elsewhere.

dosco's picture


I disagree that this is necessarily a dangerous endeavor...converting 3 phase to "normal" is fairly common in machine shops. Suggest you contact some local machine shops (CALL SEVERAL) in the area and ask them if they use phase converters ... if they do, ask for a reference to their electrician(s).  I'm sure you could go directly to an electrician as well.

Regardless let the electrician tell you about the safety aspects.

On spam ... lately we've been seeing a lot of "advertisements" for video broadcasts/coverage of UK soccer matches.

Good luck, hope it works out for you.


MarkS's picture

Converting to 1-phase may be common in machine shops, but commercial 3-phase appliances can, and sometimes do, operate at voltages far above household voltages. It *may* not be possible and could be dangerous.

Regardless, talk to an electrician. This is NOT a job for someone that has no experience in this. You could very easily kill yourself or set your house on fire. Or both...

MANNA's picture

Ok, i hate to comment on this but I will. I moonlight from my baking career as an electronic technician. Not just computers but large systems and alot of power services equipment. Sounds like the guy who sold you the oven wanted you to put in a converter to change your house power to 3 phase for the oven. Not change the oven. You can get a converter from places like grainger or graybar . Now will your power feed be able to handle the load you will put on it. Im going to say probaly not. You would have to upgrade your box and maybe the feeder cables. And if your going to do that it would make sense to just get 3 phase service ran to your house. Thats going to cost money but in the long run not as much as you will pay for electric running that converter and oven on single phase. I priced out a oven for my house a few years back and the cost was crazy. I can only imagine what it would be in hawaii. A small wood fired oven made sense both in installation cost and operating cost. Long walks on the beach collecting firewood sounds nice too. A final word, hire a licensed electrician to perform your work.

BobBoule's picture

One of my hats in my 30+ year career in the high tech industry was to design power systems for large data centers. I would personally not even consider trying to figure this out on my own if I were in your shoes because there are far too many details to analyze than can be discussed here. As normal single phase electrical feed for household use is typically not intended to deliver the high power that industrial loads require, which is why industrial applications require three phase empower, however you have a solar system so it might be possible to swap the controller and create a three phase solar powered system, then run a three phase feed to the oven and rewire a single phase feed to the house for residential uses. The electrician will figure out how to balance the loads so the system remains reliable, just make sure that they are reputable and have industrial as well as solar power system experience before you talk with them.

chris319's picture

just make sure that they are reputable and have industrial as well as solar power system experience

And are fully licensed.

DavidEF's picture

Disclosure statement - Laws may be different in your area. Please consult governing authorities before making any modifications to your home's electrical wiring or your oven's internal wiring.

Okay, now, there are a couple things you can do. Converting your home to three phase is a bit expensive, and WILL require a qualified electrician, and MAY require that the electrician have qualification in photovoltaic systems as well. I don't think it is your best option, but it is definitely a possibility. I think you would be better off changing the oven over to single phase power for at least two reasons. One, is that it is the only thing you have that is three phase. There will be no benefit to changing your house over to three phase. If you had a motor load, you would get better efficiency with three phase power. But then, your electricity is practically free anyway!

To change the oven over to single phase power, the elements would be rewired a little to run all of them off of two phase legs rather than three. Usually, this is not a big deal to do. A qualified electrician could do it quite easily. But, the oven probably has a service access door to get to the wiring to change it, and inside that door, or somewhere close by should be a wiring diagram showing how the elements are wired together and how to change it for single phase power. If not, then at least the info should be available online.

The number and type of elements will determine the exact wiring necessary. The most challenging to convert would be three 120v elements, because they would each be wired with one hot leg and one neutral. If you take away one phase leg, and leave two, then one of those phases will need to carry two elements that way, and the other phase will carry one element. This is unlikely, though, because the elements are usually 240v, wired with two hots, not one hot and a neutral. In that case, you just make sure one end of each element is tied to your first phase and the other end is tied to your second phase.

Let me know if there is anything else you'd like to know about rewiring the oven elements. Oh yeah, a phase converter is usually used with motor loads. I can't imagine why the manufacturer of your oven would recommend using one for this heat load. But, if you want to use a phase converter, find out which one exactly your manufacturer recommends, and get that. There are different kinds of phase converters, and some of them may not work at all with your oven. As someone said above, a phase converter changes your home power source, adding a third phase leg for the equipment to use. Generally, they are very limited in their application by load size and type(s). To install a phase converter, a qualified electrician is strongly recommended (and may be legally required in your area).

David Esq.'s picture
David Esq.

I think DavidEF should be flown in, or at least given free room and board, for a working vacation in Hawaii, and he can fix the oven. To make sure it is fruitful, see if you can snap a photo of that wiring diagram he references. Even if he can't come to you, it will help you discuss the matter with and electrician before he gets to you and tells you he can or can't help. 

Also, suggest contacting the manufacture directly and asking if you can convert the oven instead of the home, and whether/why a phase converter is needed. That information should help the electrician who may or may not think it is necessary to follow. 


DavidEF's picture

Definitely consult the manufacturer before making any modifications to your oven. And by the way, flown-in AND room-and-board would be the minimum needed to get me to come there. It will certainly be cheaper to get a local electrician to do the work. But, I'll help as much as I can.

Moya, do you have the exact electrical specifications available for this oven? I tried to look it up online and didn't get anything. As MarkS said above, the voltage of the oven may be higher than the voltage your house can supply. If that were the case, you would not be able to simply rewire the oven to work in your house. Well, you still could, but it would be under-powered and wouldn't heat all the way up.

Moya Gray's picture
Moya Gray

Thanks so much everyone for your thoughtful responses!  You are all so kind!

Manna - there is no 3 phase power to our residential area and the closest source  is 1 mile away!  To bring that into our home is more than expensive, and I don't have enough influence to even make it possible LOL!  I don't know about collecting firewood on the beach here cause all the storm tossed wood seems to go elsewhere- we don't even get Japanese glass-ball fishing floats anymore!

Dosco and MarkS - we will absolutely work with licensed electricians - I do not want to burn my home down!

Bob Boule your suggestion about three-phasing from the solar is intriguing!  I'll check that out!!! and Chris319- we've had such a rush of pv installations that I almost think some of these guys may NOT be fully licensed - great recommendation! Thanks.

I want to especially thank the David Duo for their suggestions to come out here and rewire the oven!  I might take you up on that if the electrician doesn't call me soon! 

David EF - thanks especially for your thoughtful responses. It looks like we might have enough amps running through the house for a proper single phase conversion, but we may have to change the panel.  for two days I've been on the phone with the manufacturers American based tech (very helpful guy), the power company and an electrician, checking out the noise that phase converters make, getting wiring diagrams, figuring out the amps for this oven, and generally analyzing the situation.  we've been told that the 2-decks and steam generator in total are 32 amps, which we think is ok. We still have to confirm with an electrician. Also I need to be sure that the oven's wiring can handle that much amperage.

ive asked the manufacturers tech guy for the wiring diagram and he's going to email the German manufacturer for it and email to me.

my conclusion today is simply that paradise is expensive! LOL!  So we are still assessing the rewiring route, as i don't think I could stand the noise of a phase converter while baking. 

Hmmmmm, all I want to do is bake!  ah well, i love learning new things so it's great!

David Esq - from one Esq to another, are you still practising?  What area of law? My law school here is celebrating its 40 years of existence.  they've asked me to bake bread for the party next week! So I really need my oven!

 thanks guys and may I continue to pick your brains?  


Aloha, Moya

David Esq.'s picture
David Esq.

Still practicing. Commercial litigation of all sorts and shapes.  For the non attorneys, someone once described commercial litigation as Tony the Tiger sues Tucan Sam.  I thought that was funny. Commercials. Get it?

People ask to buy my bread and I tell them I can only sell it at $1,200 a loaf.  Based on my hourly rates, that is a huge bargain. And even then, I am willing to offer volume discounts or throw in a tin of cookies.


DavidEF's picture


The amperage shouldn't be an issue for the oven. The voltage may be. Most homes are wired for around 240v, but there are some commercial ovens that are wired for 480v power. If the elements in your oven are made for 480v, then giving them 240 volts would mean you're only giving them half the power. And your oven's controls may not even work at all without the proper voltage.

If the oven is the same voltage as your house wiring, then you can begin to think about amperage. With the removal of one phase, the other two phases, or at least one of them, depending on how it is wired, will carry more amperage than the oven was designed for. This shouldn't be a big problem for your oven, but needs to be taken into consideration when wiring it, because the wire size will need to be bigger to carry the extra load. And the circuit breaker will need to be sized larger as well.

As for the phase converter, it wouldn't have to be installed in the kitchen, unless the manufacturer insists on it for warranty. It just converts two phases into three, and can be installed anywhere. Typically, it would be installed right next to the electrical panel, but if that would still be a bad place for noise, you can put it practically anywhere you want, within certain limitations. The problems I have with a phase converter are that it is expensive to buy and to use, compared to having real three-phase power. Sometimes, it is the best option, but in this case, I'd try my best to get the oven to conform to the house rather than trying to conform the house to the oven.