Delta 3-Phase 4-Wire System (120/240V)

[@matt59fire]

Line B is high leg. Delta 4 wire 3 phase high leg 120/208/240v is as follows. (B to N) is 208. A to N is 120, C to N is 120. A to C is 240, A to B is 240, B to C is 240

[@00crashtest]

Phase A is the high leg as required by the Canadian Electrical Code, as found from online forums. Phase B (marked orange) is the high leg as required by the National Electrical Code in the United States of America.

[@kylecondran]

A is definitely the high leg I have worked on several of these systems they are quite common out in the country

[@waynenocton]

Pretty wild that it changes for us and Canada, but I’ve also seen the high leg on the C in the panel and seen people say that it used to be the way it was mandated. I see the 208 high leg warnings, orange leg, and see panels with all the high legs blocked off, but here using a separate panel seems like a great idea. I’m not an electrician, so speculating here, all the wok I do on this stuff gets gone over by electricians before being used anyway.

[@Sparky-ww5re]

Canadian Electrical Code I find intriguing. I'm in the USA and here, if we had a 3ø 4w delta system, the high leg must land on the B phase, for switchboards, switchgear and panelboards. Metering equipment usually is required to have the high leg terminate on the right side (phase C) Panelboards installed prior to 1975 often had the high leg on phase C. High leg conductor must be marked orange, or other effective means, at all termination points where the neutral is present. 1ø & 3ø circuits are allowed in the same panelboard.

[@AGENTSQUIDGROW]

Wow thanks man. School at home during covid has been tough, not nearly the interface needed to grasp this stuff for some people simply 50% on their own. Thanks for putting time in for us folk here. helped me alot and grasp background knowledge too in all these videos that i struggled even in previous years of schooling. You Rock

[@ZackHartle]

So glad it helped. Thanks for watching!

[@Prod.KillaTonez]

did you flip the video? are you right handed? its blowing my mind thinking you're writing everything backwards.

[@guspbr]

he just mirrored the video

[@drwhoeric]

I never knew that was the symbol for 3-phase being 3Ø. I always saw it on my 208v 3-phase delta-wye panel in our business and assumed it went to meter 30 or corrected to 31, but we really went to meter 36 at the PDU.

[@Vincxzs]

Absolutely Helpful! Thank you so much for this short and precise explanation.

[@Dane-lp7ur]

Great video! Providing an explanation for these uncommon circuit types is so helpful.

[@ZackHartle]

Glad it was helpful!

[@00crashtest]

In the United States National Electrical Code, the high leg is required to be labeled as phase B. From forums, I could find that the Canadian Electrical Code requires the high leg to be labelled as phase A. The US NEC requires the high leg to be marked orange at equipment. However, I could not find the CEC marking required for high leg. So, how does the CEC require the high leg to be marked?

[@ppellacani]

THIS IS THE BEST CHANNEL IN KZbin

[@ZackHartle]

Thanks!!!

[@rfsf207]

Thanks for explaination we can not run 3 phase load like motor and the same time running sigle phase load from divided winding.

[@Ozzy2341]

Great video , can you utilize a 3 phase wye generator 120/240 volt for backup power in the event of an emergency on a 3 phase 4 wire delta high leg ? Please explain anybody

[@TheCommonSenseProfessor]

AKA Wild Leg Delta. Good video.

[@wilsonw3029]

This is so nicely done. Thanks

[@ZackHartle]

Glad you like it!

[@beijing561]

Nice presentation. Can you confirm my understanding in real life:: A+b or c, or b+c, +ground gets you 240v but it is single phase or three phase? A+b+c+ground gets you 208 three phase right? N+b or c, + ground gets you 120v single phase right? N+b+c+ground gets you 240v single phase right? Thanks in advance

[@user-yu8ur9yi9e]

​ @ZackHartle Would it be possible to have a star delta starter for a 3 phase load on this system?

[@dessalectric]

🔥🔥🔥

[@CapnBubbaa]

I re-watched this again, when running 120/240 single phase, how does this affect the balance of the 3phase incoming load, it seems like there would some sort of imbalance to the 3phase current.

[@Sparky-ww5re]

Good observation. Yes 120 volt loads on a 3ø 4w delta system will cause some unbalance that cannot be avoided, unlike the more commonly used 208Y/120V system where each phase can be used L-N or L-L. In fact it's usually fairly easy to identify a 4 wire delta service just by looking at the transformers, assuming the building has overhead service because the transformer with the center tap will often be larger than the others, for the reason this transformer will have all the 120v loads in addition to the 240V single- or three phase loads.

[@ramonassence1875]

thanks sir

[@sauliusvaitkevicius9700]

Hey I bought draper 250a mig, have 220/400v switch, but only 4 wires, which is l1,l2, neutral and earth, few Electrician checked how plug 3 please plug, but everybody told me is only one phase, is that can be 3 phase if switch is 220/400v

[@CapnBubbaa]

Zach, when doing a 3 phase 4wire as you described... is the disconnect a Single 400 amp, even if running 100 amp panel on 3 phase, and 300 amps on single phase.. or is there disconnect on each panel... I plan to use the 3 phase for running my Air conditioning units... by running single phase from the 3 phase drop, as I understood the single phase the phases are 180 degrees exactly like a 120/240 single phase drop. just a clarification

[@Mad.Man.Marine]

So can you then use the two 120volt lines to run a 220-240volt single phase circuit ?

[@matt59fire]

Yes. 2 pole breaker

[@RonThunderbird]

Good explanation, but I'm unsure why you say it's an uncommon system?......... Although mostly for agricultural and industrial service applications, in my area they are still installed and used regularly.

[@ZackHartle]

That's fair. Maybe just around my area they are uncommon

[@matthewellis3004]

Please help clarify this question on my practice exam, keep in mind I'm in California, I think you are in Canada? maybe its different? The question is: On a Delta three-phase 4-wire secondary, how many hot wires may use the common neutral? Answer stated: 3. If I'm understanding this video correctly, A phase is un usable? Thanks for your help, I have a lot to learn

[@ZackHartle]

I would say just 2. B and C

[@Sparky-ww5re]

That really depends on the jurisdiction. Here in the U.S.A. the high leg is usually found on the B phase in panel boards, in metering equipment it found on the C phase, or in rare instances the A phase, reason being the meter requires a 120 volt connection to the B phase, so the utility must choose A or C to avoid destroying the meter, they always seem to choose C. In some installations the high leg is on the C phase throughout the building, so it is very important to be aware of this, and always verify with a meter. The high leg is required to be orange or other effective means, but I will not trust my life to that before I verify the voltages are what I think they are.

[@matthewellis3004]

@@Sparky-ww5re thanks. Didn’t know that about the meter requiring 120v, and yes, never assume voltage, always verify💯

[@UHB007]

Are you writing backwards on glass?!

[@ZackHartle]

Just fancy camera tricks!

[@Okie-Tom]

I have this system. Mine has two transformers and is fed with two of the phases. Not three!

[@Sparky-ww5re]

Open high leg delta. These are rare, and usually found on farms, where most of your stuff is 120/240 V single phase, with a small amount of 3 phase motors, such as used on grain dryers, augers conveyers and the like. In this situation the capacity of a closed delta is not warranted, and the utility will install 2 transformers instead of 3, to save costs. This service can be identified by 2 transformers, one of them is much larger than the other, the large transformer is the lighting transformer, which supplies your 120/240 single phase loads, the smaller transformer is the power transformer, this supplies the high leg, sometimes called the bastard leg or stinger leg, this is 208V to ground, so cannot be used by itself to a neutral.

[@Okie-Tom]

@@Sparky-ww5re , do you happen to have a transformer wiring diagram of my open high leg delta. I am curious how the transformers are all wired up internally! Thanks much. Tom

[@melissachartres3219]

04:02 Based ON. Not based off of. You cannot base something off of something else.

[@GH-oi2jf]

One thing bothers me about this. A wye distribution line will have a neutral, which is grounded at the transformers, and also at the service entrance of the customer. With this delta configuration shown, I assume that is the final transformer serving the customer. The neutral will presumably be grounded at the transformer and the service entrance, as with the wye, but the neutral does not run back to the substation, except through ground. Does that matter? The power company would have to keep track of the phases and always put the neutral on the BC phase when there are multiple customers on the distribution line with this configuration. How do they keep track of this?

[@ZackHartle]

These types of services are almost non-existent because they can be problematic, just like you say. You'd really only have very small amounts of load on the 120V, so it wouldn't have a huge effect overall. Also, the delta line conductors can handle unbalanced current without the neutral connection back tot he substation

[@ericpham5198]

So N-A is inverter of A-N

[@davidlydic3552]

most of the time it is B phase that is the high leg.

[@ammaromar6551]

I have a Question, why can't we connect A to N to get a 208V 1Ø? some times we have an application where it require a 208V?

[@ZackHartle]

You would end up with high neutral current and excessive heating on the BN or CN winding. These types of services are extremely uncommon.

[@00crashtest]

You can connect A to N in Canada, B to N in America, in order to get 208 volts single phase. It is that you cannot do that on any standard 3-phase closed high-leg delta transformer bank (which are 3 identical split-phase transformers connected together in delta, with only one transformer having its centre tap used and grounded) that is already operating at full capacity. Open high-leg delta transformer banks only have 2 individual transformers, which of course also means you cannot use the high leg to neutral there either. However, for a custom installation that has substantial 208-volt single-phase loads in addition to the standard 240-volt three-phase, 240 volts split phase, and 120 volts single phase, you can upsize the C-A (A-B in US) and A-B (B-C in US) individual transformers slightly, and upsize the B-C (C-A in US) transformer moderately. An example of single-phase loads that require 208 volts are Japanese split-phase cooking appliances from West Japan, which are designed to operate at 200 volts 60 hertz. Yes, Japan's electrical grid is split right along the Fuji river, where the west (Shizuoka City) uses 60 Hz and the East (Fuji City, also located in Shizuoka Prefecture) uses 50 Hz. A custom closed high-leg delta transformer would be very useful in enabling straight 240-volt Canadian and American appliances (welders, induction cooktops, and electric vehicle supply equipment), 120/240-volt Canadian and American appliances (ovens, ranges, and dryers), 220-volt (rated for up to 240 volts as part of IEC harmonization) European cooking appliances, 240-volt (rated for down to 220 volts as part of IEC harmonization) British 3-kilowatt water kettles for quick boiling, and 200-volt Japanese commercial-grade rice cookers, to all be used without any additional transformers, which reduced energy losses from conversion and also saves material.

[@00crashtest]

Chances are, Japanese 200-volt appliances that have heating elements work just fine on 240 volts as long as they are not on high setting. That has been stated on many posts on expat and travel forums. That is because the resistive heating elements will overheat on high setting when running at 240 volts. So, while there is no prohibition on using the high-leg to neutral under the United States' National Electrical Code (unsure about the Canadian Electrical Code), one should not bother with making a branch circuit with that because the existing range and dryer branch circuits can supply a 200-volt Japanese appliance that involves heating just fine with just a plug adapter. So, a traveller from Japan who has unused luggage space could very well bring their 200-volt space heater as long as they don't use a high setting and a NEMA 14-30, 10-30, 14-50, 10-50 , 6-50, 6-15, or 6-20 plug adapter is provided by the host in North America.

[@jefferymurray9685]

Very common in Chicago

[@ZackHartle]

Interesting. We don't see many in Alberta

[@hgncompany7937]

I have the same service, can I connect a 3ph motor 220v?

[@ZackHartle]

Should be able to

[@antmartin8]

@@ZackHartle how is the wiring done to achieve the 220v 3ph in said Delta system? Thanks 👍🏻

[@TheCompton1963]

Delta has neutral?! 🤔

[@ZackHartle]

It can!

[@00crashtest]

It's called a high-leg delta. The delta can be open or closed, but closed is highly recommended because it allows the full combined capacity of all 3 pairs transformer windings to be used. Whereas, only 5/6 (usually only stated as the approximated value of 86.6% in textbooks) of the combined capacity of all 2 pairs of windings can be used in an open delta. This means one is essentially wasting money and materials in using an open high-leg delta transformer.

[@jacobisrael5594]

Keep studying bro