One Building, With Two Services, NO meters

[alyoshak24]

Hello wizards,

I have a couple of questions but first some context. Our crew is working on a project on a older facility (1960s or 50s) with an overhead xmfr feeding multiple buildings (maybe 3-5). Some buildings have multiple services and others only a single service. Utility stated that this is a metered primary that meters the aggregate load from all the buildings it feeds and that is why there are no individual meters on the buildings (dont know why that is). Most buildings are small office buildings, cafeteria, dorms and "welding shops" / "automotive shops" / "carpentry shops" etc for teaching. the xmfr info is as follows:

PRIMARY SERVICE: 25/14.4kV, 3PH, 4 WIRE.
BUILDINGS SECONDARY SERVICE: 120/208V & 120/240V, 1PH & 3PH, 3 & 4 WIRE

We are tasked to replace the main breaker panels for a building that has two service drops, a 225A 3P 120/208 42 space MBP and a 200A 120/240V 24 space MBP. These Main Disco Panels are right next to each other inside the building. Now we noticed that the overhead service drop for the single phase is tapped from the 3phase service wires L1, L2 but NOT the neutral. The neutral "looks" like it also tapped but upon closer inspection, its just hanging.

When we opened the service panels/discos inside the building we noticed that in the single phase 200A disco L1 L2 N were landed properly BUT there was a bonding jumper from the neutral lug on the single phase 200A panel to the 3Phase 225A panel.

This is the first time we EVER encountered something like this. Our initial reaction was to get utility to reconnect a neutral that was never connected in the first place and NOT jump the neutral from the 3Phase panel to the single phase panel. However, we are unsure if it was deliberately left that way due to the transformer config uration.

Can you great electricians share your wisdom and help clarify because the single phase panel readings were 120 L1-N and L2-N and 240 L1-L2, and the three phase panel readings were 120 L1 - N, L2 - N, L3 - N, AND 208 L1-L2, L2-L3, L1-L3. so if the readings came out correct for the corresponding services while the neutral was improperly jumped between the panels, then WHy didnt they just tap from the neutral service wire that attached to the 3PH service drop ?

Respectfully,

the original bobby wayne

 

[LarryFine]

Who pays the bill now? Is it somehow divided among the customers?

The neutral should follow the same pathway as the line conductors.

You would have to find out why from whomever wired it that way.

I would first guess as a way around a damaged (or missing) conductor.

 

[synchro]

... Now we noticed that the overhead service drop for the single phase is tapped from the 3phase service wires L1, L2 but NOT the neutral. The neutral "looks" like it also tapped but upon closer inspection, its just hanging.

... Can you great electricians share your wisdom and help clarify because the single phase panel readings were 120 L1-N and L2-N and 240 L1-L2, and the three phase panel readings were 120 L1 - N, L2 - N, L3 - N, AND 208 L1-L2, L2-L3, L1-L3.

Are you sure that the single phase panel L1-L2 reading is 240V and not 208V like in the three phase panel?

 

[Joethemechanic]

Are you sure that the single phase panel L1-L2 reading is 240V and not 208V like in the three phase panel?

Not getting 208 WYE and 240 single, without an additional transformer. Somebody is missing something.

The only way I see of getting both voltages out of one transformer connection would be 240/120 Delta high leg and that would be only single phase 208 from B phase to Neutral

 

[alyoshak24]

Who pays the bill now? Is it somehow divided among the customers?

The neutral should follow the same pathway as the line conductors.

You would have to find out why from whomever wired it that way.

I would first guess as a way around a damaged (or missing) conductor.

Hi Larry, the bills are paid by the facility manager, all individual buildings electrical usage are metered by one transformer so the facility owner or manager gets one big bill every month. Whoever wired it this way was three generations ago and they dont have the previous installers information.

 

[alyoshak24]

Are you sure that the single phase panel L1-L2 reading is 240V and not 208V like in the three phase panel?

Yes,

Not getting 208 WYE and 240 single, without an additional transformer. Somebody is missing something.

The only way I see of getting both voltages out of one transformer connection would be 240/120 Delta high leg and that would be only single phase 208 from B phase to Neutral

I am going to call the utility and ask them what type of configuration is this XMFR, this project is in a small town in TN, more rural than urban

 

[alyoshak24]

HERE IS A PICTURE OF the ovERHEAD TRANSFORMER

 

[LarryFine]

HERE IS A PICTURE OF the ovERHEAD TRANSFORMER

High-leg, open delta.

 

[Joethemechanic]

Ye

High-leg, open delta.

Yeah only 2 pole pigs.
240/120 open delta "four wire" for power and light
If someone is seeing 208 they are measuring from N-G to phase B

 

[Joethemechanic]

Here is the typical 240/120 open delta connection

 

[Joethemechanic]

And if you are replacing the breaker panels, you are going to have to figure for extra spaces because you've got a high leg (N-G 208v) bar on your bus. That should only be used by the center pole of 3 phase breakers. So if you have a lot of single phase loads a lot of spaces are unusable.

You aren't going into meter sockets on this, but if you do go into a high leg meter socket, some installations in some POCO operating areas, during some time periods, cross the B high leg and label it either a or b (I forget) due to something With the original "high leg" service being an "Add On" for rich people with central air in big houses.

But just be aware, sometimes the meter sockets can be a little tricky, and your meter is your friend

 

[alyoshak24]

I love you guys. Thank you. Im not sure but if im ever in Hazleton PA or Richmond VA, Please allow me to buy you a drink, Cheers Gents.

 

[alyoshak24]

And if you are replacing the breaker panels, you are going to have to figure for extra spaces because you've got a high leg (N-G 208v) bar on your bus. That should only be used by the center pole of 3 phase breakers. So if you have a lot of single phase loads a lot of spaces are unusable.

You aren't going into meter sockets on this, but if you do go into a high leg meter socket, some installations in some POCO operating areas, during some time periods, cross the B high leg and label it either a or b (I forget) due to something With the original "high leg" service being an "Add On" for rich people with central air in big houses.

But just be aware, sometimes the meter sockets can be a little tricky, and your meter is your friend

We are installing a subpanel to account for all of our single phase loads (85% of the circuits)

 

[Joethemechanic]

We are installing a subpanel to account for all of our single phase loads (85% of the circuits)

A single phase sub should have phases A and C, neutral and an EGC.

Just be careful. on the utility side the high leg may be marked as C phase, and once it's on the customer side it becomes B phase. Check everything with your multimeter. If you land the high leg wrong you'll have 120 volt circuits with 208 applied to them.

 

[hillbilly1]

And if you are replacing the breaker panels, you are going to have to figure for extra spaces because you've got a high leg (N-G 208v) bar on your bus. That should only be used by the center pole of 3 phase breakers. So if you have a lot of single phase loads a lot of spaces are unusable.

You aren't going into meter sockets on this, but if you do go into a high leg meter socket, some installations in some POCO operating areas, during some time periods, cross the B high leg and label it either a or b (I forget) due to something With the original "high leg" service being an "Add On" for rich people with central air in big houses.

But just be aware, sometimes the meter sockets can be a little tricky, and your meter is your friend

The high leg is always on “C” phase in the meter for correct meter operation. Code just moves it to “B” so it is always the middle buss on gear that the back can be removed. There are quite a few installations, with the high leg improperly staying on “C” in the service disconnect and panels.