I have a 3 phase delta high leg service on a residence in texas. I am changing the service. I want to use a three phase meterbase and feed that into a single phase panel box. I want to install a 3 phase fused disconnect next to the panel box. I want to take the high leg and run it directly from the panel box to the three phase fused disconnect without using a three phase breaker since it is a single phase panel box. Then take the other two phases from a 2 pole breaker in the panel box and feed them to the same 3 phase fused disconnect. That circuit would be for the outdoor a/c. Any problems?
3 phase with delta high leg
- Thread starter difowler1
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LarryFine
Master Electrician Electric Contractor Richmond VA
- Location
- Henrico County, VA
- Occupation
- Electrical Contractor
Yes. If you get the two 120v lines from your 1ph panel, the high leg needs to be fed from there as well.
You're better off supplying the 1ph panel and the 3ph disco from the meter directly or through a gutter.
LarryFine
Master Electrician Electric Contractor Richmond VA
- Location
- Henrico County, VA
- Occupation
- Electrical Contractor
Depends on how much 1ph load you have and how much wasted panel space there would be. 1ph line-to-line loads that don't need the neutral can use the high leg.
- Location
- Illinois
- Occupation
- retired electrician
I would just run two sets of conductors from the meter, or if the meter does not permit two sets, from a splice point on the load side of the meter. One set would be sized for the AC load and run to the fused disconnect that would be service disconnect #1. The second set would be sized for all of the 120/240 volt loads and would run to the main breaker in the panel and that would be service disconnect #2.
- Location
- Illinois
- Occupation
- retired electrician
One other option would be a custom panel. It would have a three phase main breaker, a 3 pole breaker for the AC, and the rest of the space would be set up for the 120/240 volt single phase loads. There would be no "bus fingers" for the high leg in that part of the panel. I have installed a couple like that for an industrial lab application where they only had a couple of 3 phase loads and the rest were 120/240 single phase loads. I have no idea how much extra that would cost. It might not be a cost effective solution.
electrofelon
Senior Member
- Location
- Cherry Valley NY, Seattle, WA
Yeah a class 320 socket would cost more but I often find it worth it as you get the dual lugs and saves the materials and hassle of making a splice/tap after the meter.
It really all depends on the overall amperage of the service, the size of the circuit required for the 3ph AC unit, how many other appliances there are that are actually 3 phase, and, how many, if any, 1ph appliances will be able to utilize the wild leg as their supply to be able to offer any suggestions.
As it is now, with the information we have, we're all just guessing.
JAP>
As it is now, with the information we have, we're all just guessing.
JAP>
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