Its been years since I worked on two phase 5 wire in Philly. The PECO on line blue book for services still list two phase services. Back in the 1970 & 80's if a location has two phase service they allowed new owners to have the two phase reenergized . The area in Northeast A Philly at very busy Frankford & Cottman Avenue still has two phase. When I installed a single & three phase service for a store they told me about the two phase. Last year I did a search for two phase four poke fused 30 amp safety switch and could not find one. Last time I purchased one was 50 years ago and cost twice as much as a 3 pole fused 250 volt safety switch. I wired in a few two phase motors & a two phase rewound two speed two phase 8 lead motor for an old box company. The great supervisor of Philly L&I used to attend the 8 very informative IAEI yearly meetings. Surprised they would not allow use of yes obsolete two phase service.
Two Phase to Single Phase (split phase) Conversion
- Thread starter TFelc
- Start date
Did some more digging in PECO blue book service requirements. 8.9.1 states If a customer requests to maintain two phase service after equipment failure, they shall upgrade to current transformer & submit S&M ( Service & Meter Application ). PEVO figure 8-15 shows current transformer installation for 2 phase 120/240 volt 5 wire service. I was an electrician at the North Philly slaughter house that Joe Frazer worked for. They still had a few two phase motors. They reused several 2300 to 240 volt transformers to feed a building across the street from main building with 2300 volt three wire two phase. The connected a wire from each phase to make the third wire and thinking that connection pulled 1.41 more current. They used the two phase to feed a lot of the lightning & 120 volt loads. Bad thing with two phase motors if you cross phase a 240 motor would only get think sround175 volts burning motor out. We would mark one phase with red tape and the other phase with blue tape. Heard Detroit at least up to late 80's still had a lot of two phase in use. When they purchased a large truck garage it still has two phase service but we refeed it from main switchgear. Somebody did a Rube Goldberg on two two phase exhaust fans. They mounted two 2 pole two fuse safety switches and made a flimsy connection bracket to turn both safety switches off at a time to secure two phase power. Back in the early 1960's helped my electrician dad wire a new 2 or 3 HP Bridgeport milling machine.
Eddie702
Licensed Electrician
- Location
- Western Massachusetts
- Occupation
- Electrician
Springfield, MA used to have some don't know if it is still there.
kwired
Electron manager
- Location
- NE Nebraska
- Occupation
- EC
Square D catalog still has four pole fused safety switches and even six pole switches in it. Have to go to the heavy duty 600 volt section of the catalog for both of these. It does say not suitable for service entrance on that page. 4 pole has 30 amp to 400 amp versions 6 pole has 100 and 200 amp versions.
Been awhile but used six pole safety switches on roof top two speed cooling tower fans. Cannot remember the price but they were expensive for ones rated 60 amp 600 volts. Back in the 1970's Arrow Hart & Allen Bradley made bolt on power pole for three pole starters to rep!ace an old four pole two phase starter. Just curious do many of fellow electricians come across two speed three phase motors on new installs ? Now with great energy saving versatile VFD'S wonder if two speed motors are dinosours.
I guess if you have an existing two phase system you'd weigh the pros and cons of keeping it with your client, the OP stated that there is no-longer any industrial motor loads so 4-pole disconnects would not be needed.
I can think of a few pro's of keeping it:
I can think of a few pro's of keeping it:
- The answer to the OP's question is yes it can be split into two single phase disconnects.
- The line current for a given kVA in a 5-wire two phase system is less than in a 4 wire three phase 208 and 1/2 that of single (split) phase.
- The existing transformer bank is designed for a two phase load, shifting all the load to one phase may overload the PECO side.
- Two new balanced 120/240 feeders can be connected one to each phase, nothing special needed.
- Two standard single phase panels can be placed on each phase, no 4-pole required.
- 120/240V is better than 120/208 3-wire open wye for apartment feeders, can reduce the neutral size.
- 120/240 is more common than 120/208 for dwelling unit loads.
- VFD's can create 3-phase from single phase, but larger ones are needed.
- Historic one of a kind system that was unique to that area may add value to the building.
- If PECO ever wanted to drop two phase support the 5-wire service could be converted to a parallel single phase.
- Non standard system.
- No 480 or 208 voltages available if equipment needs 3-phase a transformer is needed.
- A larger VFD is needed to run 3-phase motors off single phase.
- Electric rates may be less?
- ?
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kwired
Electron manager
- Location
- NE Nebraska
- Occupation
- EC
Pretty much all the two speed three phase motors I have encountered in recent years have been motors on older equipment.
I still do run into multi speed single phase motors though that maybe is starting to become less common. Often on HVAC or other air handling applications.