Electrician Talk banner
1 - 20 of 22 Posts

·
Registered
Scada Supervisor
Joined
·
3,535 Posts
Discussion Starter · #1 ·
This picture came from a closed post

Guts are only A-B N-G Why the 3 phase rating?, Or back feed L1-L2 on right.

155696


Cowboy
 

·
Registered
Power distribution and controls
Joined
·
912 Posts
The delta breaker (3 phase) as I remember the name was mounted on top of the buss so the 3rd wire that came through from the meter could be landed on it. The only thing that was 3 phase was the ac condenser. By the mid 70's the utility would go out of their way to get rid of those services.
I took ~ 100 of those off the walls of homes. The city even made it easy for the home owner to pull the permit.
 

·
Registered
Residential remodeling
Joined
·
305 Posts
Back in the 80's I used to try to get the A/C man to use 3 phase just because I hated to waste having 3 phase available. They refused because it cost more.
I believe NEC now outlaws using a 3 phase breaker in a single phase panel.
 

·
Bilge Rat
motors and controls.........
Joined
·
8,411 Posts
As others have stated, it is a ∆ breaker. Then service is 120/240 3Ø 4 wire ∆.

The panel is often a split-bus type and one of the top breakers is a 3 pole ∆ breaker. The input side of this breaker consists of 2 normal bus stabs plus an additional terminal on the 3rd pole. This terminal is where the high leg from the meter lands.

Basically it was a standard 2 pole breaker with a 3rd pole 'added on' and the 3rd pole had a terminal for the input rather than a bus stab.

The output side is 3 standard terminals like you'd find on any 3 pole breaker.

The purpose of all this is because back in the 60s and 70s, air conditioning was becoming popular. There were both single and 3Ø units available, the 3Ø ones cost a bit less and were far more reliable plus they used less KW per BTU of cooling.

I've seen several subdivisions built in the 60s and 70s that had this system in both central Oregon and northern Nevada. They were always overhead and the pole had a good-size 120/240 transformer plus a smaller high-leg one.

The high leg in the meter base was always C phase.

Also, as noted, they are not legal anymore.
 

·
Registered
Ready Mix concrete plant electrician
Joined
·
2,494 Posts
Umm, the label says 240 volt 3 phase 3 wire grounded B. If that’s the case, then the grounded conductor, the B phase, would land on the neutral-ground bus wouldn’t it?
 

·
Bilge Rat
motors and controls.........
Joined
·
8,411 Posts
Umm, the label says 240 volt 3 phase 3 wire grounded B. If that’s the case, then the grounded conductor, the B phase, would land on the neutral-ground bus wouldn’t it?
Yes it would but I was referring to the diagram on the left side. It shows a 4 wire ∆ system with a ∆ breaker.
 

·
Registered
Ready Mix concrete plant electrician
Joined
·
2,494 Posts
Yes it would but I was referring to the diagram on the left side. It shows a 4 wire ∆ system with a ∆ breaker.
Oops, yes it does show one of the elusive Delta breakers. Sorry, carry on.
 

·
Registered
Ready Mix concrete plant electrician
Joined
·
2,494 Posts
Delta breakers are not allowed per NEC
Good luck finding one to even try and violate the code. I think @JRaef is the only one to post a picture of one. Around here you would have a easier time finding Bigfoot riding on a unicorn than someone who has even heard of let alone seen a Delta breaker.
 

·
Chief Flunky
Field Service Engineer
Joined
·
2,389 Posts
As others have stated, it is a ∆ breaker. Then service is 120/240 3Ø 4 wire ∆.

The panel is often a split-bus type and one of the top breakers is a 3 pole ∆ breaker. The input side of this breaker consists of 2 normal bus stabs plus an additional terminal on the 3rd pole. This terminal is where the high leg from the meter lands.

Basically it was a standard 2 pole breaker with a 3rd pole 'added on' and the 3rd pole had a terminal for the input rather than a bus stab.

The output side is 3 standard terminals like you'd find on any 3 pole breaker.

The purpose of all this is because back in the 60s and 70s, air conditioning was becoming popular. There were both single and 3Ø units available, the 3Ø ones cost a bit less and were far more reliable plus they used less KW per BTU of cooling.

I've seen several subdivisions built in the 60s and 70s that had this system in both central Oregon and northern Nevada. They were always overhead and the pole had a good-size 120/240 transformer plus a smaller high-leg one.

The high leg in the meter base was always C phase.

Also, as noted, they are not legal anymore.
That doesn’t sound right. Delta high leg requires orange for the high leg. I’ve seen color codes as brown orange yellow (using the HV color scheme in LV) as well as black orange red or black orange blue sort of following convention and Code. But either way the high leg is always B.
 

·
Chief Flunky
Field Service Engineer
Joined
·
2,389 Posts
Delta breakers are not allowed per NEC
What section?

There is tons of commercial high leg delta out there. Never seen it residential but it’s very common. Our warehouse has it. Many municipal water plants have it. And that’s just delta high leg. Delta delta (ungrounded) is in my opinion not a good idea but last I checked it’s 100% legal and still common some places where they haven’t converted to high resistance or delta wye.
 

·
Registered
Ready Mix concrete plant electrician
Joined
·
2,494 Posts
What section?

There is tons of commercial high leg delta out there. Never seen it residential but it’s very common. Our warehouse has it. Many municipal water plants have it. And that’s just delta high leg. Delta delta (ungrounded) is in my opinion not a good idea but last I checked it’s 100% legal and still common some places where they haven’t converted to high resistance or delta wye.
I think he’s alluding to a “Delta breaker”, a breaker where the high leg is landed on the breaker from the meter, and the other two phases come from the bus work. The high leg is essentially looped through the breaker. It would be good for one load only. Generally a A/C unit so I’ve been told.
 

·
Registered
Ready Mix concrete plant electrician
Joined
·
2,494 Posts
That doesn’t sound right. Delta high leg requires orange for the high leg. I’ve seen color codes as brown orange yellow (using the HV color scheme in LV) as well as black orange red or black orange blue sort of following convention and Code. But either way the high leg is always B.
I don’t understand everything I know about the metering of high legs, something about the proximity to the neutral for the metering. I have seen numerous high leg Deltas where C phase is the high leg. They are always colored red also. Red was the old standard up until the 70’s. Ready-mix concrete loved the old high leg Deltas for quick and dirty 3 phase and 120 volt single phase power. It’s actually a treat to do work on a 480 system. The wires are smaller and the starters are also.
Nothing like pulling #8 wire to a NEMA 2 or 1 3/4 starter for a 10 hp motor on a 230 system, what a pain.
 

·
Bilge Rat
motors and controls.........
Joined
·
8,411 Posts
That doesn’t sound right. Delta high leg requires orange for the high leg. I’ve seen color codes as brown orange yellow (using the HV color scheme in LV) as well as black orange red or black orange blue sort of following convention and Code. But either way the high leg is always B.
Often, the high leg wasn't colored at all, it was the smallest one from the meter, usually a #6. The others were usually #2s and a #4 for the neutral.

Most of the ∆ breakers I saw were 30 amp though some were 60s.

As far as it being on phase C, it was required to be on C for the meter. All 240∆ feed-through meters need the high leg to be on C.

Back when these were installed, the high leg was usually red and often on C in a 3Ø panel though sometimes it was blue.
 

·
Bilge Rat
motors and controls.........
Joined
·
8,411 Posts
What section?

There is tons of commercial high leg delta out there. Never seen it residential but it’s very common. Our warehouse has it. Many municipal water plants have it. And that’s just delta high leg. Delta delta (ungrounded) is in my opinion not a good idea but last I checked it’s 100% legal and still common some places where they haven’t converted to high resistance or delta wye.
408.36(E) Delta Breakers. A 3-phase disconnect or overcurrent device shall not be connected to the bus of any panel board that has less than 3-phase buses. Delta breakers shall not be installed in panel boards.

I too have seen tons of 120/240 3Ø 4 wire ∆ systems thought a lot of them around here have been converted to Ys.

The ∆ breaker provides service to only one 3Ø load, everything else in the panel is 120/240 single phase.
 

·
Bilge Rat
motors and controls.........
Joined
·
8,411 Posts
I think he’s alluding to a “Delta breaker”, a breaker where the high leg is landed on the breaker from the meter, and the other two phases come from the bus work. The high leg is essentially looped through the breaker. It would be good for one load only. Generally a A/C unit so I’ve been told.
That's exactly what it is.
 

·
Chief Flunky
Field Service Engineer
Joined
·
2,389 Posts
408.36(E) Delta Breakers. A 3-phase disconnect or overcurrent device shall not be connected to the bus of any panel board that has less than 3-phase buses. Delta breakers shall not be installed in panel boards.

I too have seen tons of 120/240 3Ø 4 wire ∆ systems thought a lot of them around here have been converted to Ys.

The ∆ breaker provides service to only one 3Ø load, everything else in the panel is 120/240 single phase.
In resi makes sense since the one and only load is the HVAC. But it seems crazy to eliminate it. Tons of office buildings fit the same configuration...lots of 120 loads, maybe some appliances that are designed for 240, and a few HVAC units that need 208-240 three phase but relatively speaking the 240 load is small. 208/120 causes a lot of hassle because a lot of commercial/residential loads are 240 only.
 

·
Bilge Rat
motors and controls.........
Joined
·
8,411 Posts
In resi makes sense since the one and only load is the HVAC. But it seems crazy to eliminate it. Tons of office buildings fit the same configuration...lots of 120 loads, maybe some appliances that are designed for 240, and a few HVAC units that need 208-240 three phase but relatively speaking the 240 load is small. 208/120 causes a lot of hassle because a lot of commercial/residential loads are 240 only.
I've seen quite a few older buildings, usually downtown, that had a 75 or 100KVA single phase pole-mount pot and a 10 for the high leg.

They had an oil-fired steam boiler and no A/C, the only 3Ø loads were the circ fan and sometimes the boiler feedwater pump.

Pretty common at gas stations too, but the single phase pot was smaller and the only 3Ø load was an air compressor.
 
1 - 20 of 22 Posts
Top