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What type of service is this?

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  • What type of service is this?

    I'm turning my basement in to my work shop, I have a bunch of single phase 120/240 volt equipment and I just picked up a lathe that is 3 phase 220. I figured that I will use a phase converter for all the 3 phase equipment (1 for now and one more piece down the road for a total of 2). My question is I think that I might already have 3 phase in the house.

    If you open up the cabinet below the meter you see where the wires come into the house (total of 4) then they go up through the meter then through a conduit to the main breaker panel and one small breaker box for the AC.

    Now I put a volt meter on the wires in the cabinet where the wires come into the hose. The wires go as follows "Red, Black, Black" and a white wire at the bottom of the cabinet which I assume is the ground. When it test across the red and white I get 210 volts, when I test the other two black wires across the white I get 120 volts. When I test across both the blacks I get 240 volts and when I test across either of the blacks to the red I get 240 volts.

    The words "caution red leg first phase on block" and a 3,2,1, underneath the wires in the cabinet.

    So what do you guys think, do I have 1 phase or 3 phase coming into the house.

    P.S. Here's a link to a pic of the cabinet.

  • #2
    Re: What type of service is this?

    Use care and please take these measurements and then report.

    Set meter to 250 or 300 Volts AC

    Now be very careful not to short out anything or zap yourself. Wear a face shield if you have one. Remember one wrong move and it will be fireworks and a zapping for you. This must be done with great care, but because you already took some readings I'll assume you know the dangers.

    Please connect the black (common) lead to a good ground. Then measure Voltage to all six wires starting at the left and call that #1 and the one on the right #6. Please post the readings. My bet is that 4 will read close to 120 Volts and 2 will be close to 0 Volts.

    I think someone that didn't color code the wires properly needs a good swift kick. There is color code tape and the ends should have a few inches of it wrapped around them.

    Can you get back and take a picture or two showing all connections, the cabinet and then meter and say about 2 feet all around? Also please take a good picture showing all of the meter face.

    I really think you have 120/240 single phase, but the Voltage tests will be helpful.
    Last edited by Woussko; 09-07-2007, 12:11 AM.


    • #3
      Re: What type of service is this?

      Find a 240 volt outlet like the range or dryer and measure between the two hots. If you have three phase you should get about 207v, voltage should be square root of 3 or 1.73 times what you'll get from one single phase to neutral. If it reads 240v you don't have three phase. Also post a picture of the actual breaker panel. If it has all three connections to it its definately three phase. It really seems to me you have 1 phase service as you get 240v across the hot wires. I'm not sure what the deal is with that red cable reading 210v to ground.
      Last edited by Velosapien; 09-06-2007, 11:46 PM.


      • #4
        Re: What type of service is this?

        It sounds/looks like its a 120/208/240 delta thats not marked right.A friend has this in his shop and long ago I wired most of it.Personally I really really dislike these systems because as you found 1 leg is about 208 volts.Pros make mistakes with these yes me too.The red or "stinger' leg would be about 208 to the neutral .Draw yourself a triangle on paper at the bottom of the triangle make a dot in the middle with a line off it.Each corner of the triangle is a lead off each corner to another corner you will get about 240.From the top of the triangle to the center tap at the bottom you should get about 208.A "Y" system is safer as the neutral comes from the center of the y the 240 from each tip of the y.Thats basics on transformers.Most times the wires are black red and blue marked.White is always the neutral or should be lol.
        I CAN NOT stress strongly enough to hire a pro to check it out.These things should be marked with a warning that its a delta type and it looks like someone semi tried to.3 phase is not normally put in a house specially a delta type as its mostly used for motor or resistance,ie heaters welder, loads..sounds like someone sorta converted a commercial building to a residence.Over 25 years twisting wires I never saw it put in a house.Repeat this mantra ..I will hire a pro ..I will hire a pro.All the deltas I messed with had or we put tags on the panel that it was a delta.I always used a big black marker too and wrote inside the panel in big letters ...warning delta 3 phase.They are safe systems but you MUST always THINK when wiring stuff to them.Btw that wire looks like old cloth covered it should be safe enough if it never overheated and you DON'T touch puter had trouble loading the pic.Hope that helps you
        Sam.......Now hire a pro lol..geezz i'll admit it i messed up once hooking up an electric dryer to a delta on the 3rd 12 hour day in a row replacing everything that had fried from old didnt fry the dryer but that 120 volt motor running on 208 did some fancy things.this was in an auto repair place that had a washer/dryer for the help to use.


        • #5
          Re: What type of service is this?

          This is most likely at 120/240 delta high leg service. You will get 120v to ground on 2 of the three legs and 208 to ground on the remaining leg. You will get 240 volts between any two legs. This is an old method that is very seldom used in new construction. It is mostly encountered in 1960's and earlier services. At that time it was very common in total electric residences. If this is indeed what you have, you can purchase 3 phase motors that will function on 220/240v and not need a phase converter.

          Best thing is to hire a licensed electrical contractor in your state to inspect and properly label your service. Good luck!



          • #6
            Re: What type of service is this?

            Yup, this looks like that system that they called had a BASTARD leg. You need to be careful working with this type of service. Lou


            • #7
              Re: What type of service is this?

              Well I am going to have a licensed electrician do most of the electrical work for me. I am going to run a few outlets my self both 120/240. I will probably run the 3 phase outlet me self because I have done 3 phase before at a old job. But installing a new pan, updated breaker box and running the new wires in from the outside I will leave to the pro. I just feel better now that I know what type of service I have for when I start making phone calls.

              My big question is since I have a 3 phase and I have a lathe that is 220v 3 phase can I run it on the delta 3 phase? I always though that the 3 phase was 120 degrees apart and had equal voltage on each leg? Wouldn't the 208/120/120 be unbalanced to run directly to the lathe with out balancing the voltage?


              • #8
                Re: What type of service is this?

                delta winding is balanced, and 120 degrees apart,
                you have 220 between each of the three phase legs, and on two of the legs it is split in half thus getting 120 to the neutral, and that is why you will have one wild hot leg, (more than likely the red one) that will read 208 to the neutral,
                .........| 220
                ...... /..\
                .220| | | 220

                Note:the dots are jsut space the diagram

                the bottom of the delta in the drawing is the same as single phase, of a normal home, 220 volts between the hots, and 110 volts to the neutral which is splitting the phase in half and the neutral is connected to ground (earth), in your case you have an extra hot and between all the hots it is 220 volts and 120 degrees apart, but when you meter the (wild leg) to ground you get 208 volts because of the 120 degree angle of the winding,

                when hooking up your motors you do not use the neutral you use the three hot line which will read 220 volts between them,
                your controller may use the neutral and there you need to be careful not to connect the wild leg to the controller, as if your wanting 120 volts, (if you use the wild leg you will have 208 instead).
                Last edited by BHD; 09-07-2007, 10:06 AM.
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                • #9
                  Re: What type of service is this?


                  Can you please take and post a picture showing the electric meter and especially the face of it? Also please take and post the Voltage from ground to each of the 6 connection bars.

                  Also let's clear up something. Are the wires which come in from outside coming through the rear or the bottom? The rest of us must not assume things. We need to to remember that things are not properly color coded no matter what type of service you have.

                  Here's something that may really help fast. Do you have overhead feed (outdoors) or is it underground from the road inward?
                  Last edited by Woussko; 09-07-2007, 10:50 AM.


                  • #10
                    Re: What type of service is this?

                    It's good you'll hire someone ..If you do replace everything I'd suggest putting in 2 sub panels..1 thats only used for the 3 phase and to feed a single phase sub panel.Then you can run your single phase only from that panel knowing the 208 leg isnt in that panel.And please please go to a label shop and have plastic id plates made labeling the 1 panel as being delta 3 phase.10 bucks of labels might save many dollars in equipment and yours or someones life.


                    • #11
                      Re: What type of service is this?

                      There's a link to more pics below. The voltages are as follows. 210,210,120,120,120,120. The wires are above ground and come in from the rear of the box and go out to the breaker boxes through the bottom.

                      I took a look at the wiring diagram for the lathe I want to hook up, So far I have already changed the wiring on the lathe to run on 220v 3 phase instead of 440v 3 phase . To make sure that the high leg doesn't cause any problems it looks like the only thing I have to do is wire L1 and L3 to the 120 lines and L2 to the high leg. This after I moved wire #17 to L3.

                      The coolant pump on this lathe looks like it does require a ground and there is a ground point inside the service box on the lathe so am I to assume that I should run a ground to it with the delta high leg service?




                      • #12
                        Re: What type of service is this?

                        Please do as threecreeks3 suggests and have 2 sub panels with good labeling for them. One will be for 240 Volt Delta 3 Phase and the other will be for 120/240 Volt single phase.

                        This is a 3 phase delta with one winding tapped. Are you sure this is coming into a house and not a commercial building?

                        You are wise to hire an electrical contractor. Be sure he does color code and label everything. That can save you much trouble later on.

                        Be sure the electrician checks for good grounding and upgrades grounding as needed.
                        Last edited by Woussko; 09-09-2007, 05:32 PM.


                        • #13
                          Re: What type of service is this?

                          Can you please show a photo of the breaker panel? Lou