electricalist
Senior Member
- Location
- dallas tx
This I came across today while looking at some work for the bldg. This block has 120-208 with 208 to ground and I've been to a few places there Where someone added 120 v lights . pow.
What service is this
- Thread starter electricalist
- Start date
- Status
- Occupation
- Licensed Electrician
The first pic makes it look like an old delta system. Can you get a picture of the transformers?
- Location
- Illinois
- Occupation
- retired electrician
It is a high leg delta system. It does have 208 to ground on one leg, but the phase to phase voltage would be 240. Two legs would have 120 to ground. In the picture the smaller insulated conductor is the high leg and would be used to support the 3 phase loads. If there is a single service disconnect, it would have to be a fusible disconnect as the OCPD for the high leg would have to be smaller than for the other two legs.
electricalist
Senior Member
- Location
- dallas tx
They were about half way down the block..
electricalist
Senior Member
- Location
- dallas tx
Very interesting. Now I gotta look at all the service drops on that bldg.
I had called on one of the meters to verify the suite marked on the disconnect and it had a single breaker,(not the one in the picture).
Looks like "back in the day" they were doing more actual load calc. and installing the wire accordingly.
meternerd
Senior Member
- Location
- Athol, ID
- Occupation
- retired water & electric utility electrician, meter/relay tech
I don't see the bare neutral service wire connected to anything. Doesn't that rule out three phase 4 wire high leg? Look at the meter and see what is. Is it a F 12? That's single phase 120/208. Is it F 2? That's 120/240 single phase. Could be a tap off of a three phase 4 wire bank. The insulated smaller wire is kinda weird for an overhead service drop.
electricalist
Senior Member
- Location
- dallas tx
Where on the meter will i find the F -. ? I worked on every building the previous block on both sides of the street and found 120/208 with 208 to ground on B phase.
Havent seen one space/tenant using b phase,,except the ones where somebody tried to add lights on b phase and blew out the bulbs,,,but they srent being used now.
What i call your neutral looks connected above the service point, and i thought the same about the mini wire connected. I assumed the have no 208 to ground loads so its ok to used according wire...
That's what I'm gathering. The small insulated service drop wire is sized for the B-leg load.
Is it a 2 or 3 transformer bank? 2 would make it open delta.
- Location
- Illinois
- Occupation
- retired electrician
That is not a possible combination of voltages.
If you have a high leg, it will be 208 to the neutral, the phase conductors will be 240 phase to phase, and A and C phases will be 120 volts to the neutral. The only 208 voltage on this type of system is the high phase to the neutral.
- Location
- Illinois
- Occupation
- retired electrician
The second picture shows the bare messenger conductor connected to a conductor that enters the weather head.
electricalist
Senior Member
- Location
- dallas tx
So if I check from b phase to the grounded conductor i get 208, if i check b phase to the grounding conductor i wont get 208 ? What would i get.
Im not dis agreeing since i ve been wrong way more time than right. I check anything im going to work on from a to b a to c and b to c then a to neutral b to neutral c to neutral then a to ground b to ground c to ground.
electricalist
Senior Member
- Location
- dallas tx
Sorry Mr. Don you are correct I have a seriously bad habit of calling a 120/240 volt service a 120/208.
I didnt learn about voltage types from instruction. More from being scared of electricity and checking all voltages and so 208 got stuck in my head as the correct name. Actually until i said it wrong on the site no one ever cought it.As well as a hi leg is 240 on one phaseand its the only hi leg we work with. TY SIR
- Occupation
- Licensed Electrician
Unless you have a ungrounded system your voltage to grounded and grounding will be the same since they are bonded at the service or SDS.......b to noodle 208V, b to equipment ground 208V.
- Status