I am surveying a job site to install A/C equipment in a very old manufacturing facility. Approximately 1930s-1940s. When I was in the facility today I noticed something very strange.
What I see outside is a single phase of 7620 Volts and a neutral conductor going underground from the pole in to a transformer vault in the buildings basement.
I can absolutely confirm that there is only a single phase and a neutral going to the vault from the pole outside. However, the switchboard leaving the vault has "240 Volts Three Phase" labeled on it and on every disconnect downstream of that switchboard. The transformer vault is locked by the utility company so I can not get in there at this time. I had no tools or test equipment with me today but plan on returning with some within the next few days. Can somebody tell me if they have ever seen anything like this before? Or if it is even possible to derive three phase power from this type of connection.
I would like to fully understand this type of system before we start installing, or even purchasing for that matter, three phase equipment. This building has three services, two of which I have worked with before. (Today was my first day in the older section of the building) One service is 480V 600A Ungrounded Delta (which I have confirmed) fed from a pad mounted unit substation. The other service is 240V 400A Ungrounded Delta (which I have also confirmed) fed from three cans on a pole outside of the building. But the third (and oldest) service is labeled as "240V Three phase" which clearly only has a single phase and neutral going into the vault. We would prefer to utilize this three phase service (if it is in fact three phase) that is in question, due to its proximity to the location of where the A/C units need to be installed, rather than run some 400-500 feet of conduit/conductors to the confirmed 240V Three phase service.
Any help would be greatly appreciated. Thanks.
What I see outside is a single phase of 7620 Volts and a neutral conductor going underground from the pole in to a transformer vault in the buildings basement.
I can absolutely confirm that there is only a single phase and a neutral going to the vault from the pole outside. However, the switchboard leaving the vault has "240 Volts Three Phase" labeled on it and on every disconnect downstream of that switchboard. The transformer vault is locked by the utility company so I can not get in there at this time. I had no tools or test equipment with me today but plan on returning with some within the next few days. Can somebody tell me if they have ever seen anything like this before? Or if it is even possible to derive three phase power from this type of connection.
I would like to fully understand this type of system before we start installing, or even purchasing for that matter, three phase equipment. This building has three services, two of which I have worked with before. (Today was my first day in the older section of the building) One service is 480V 600A Ungrounded Delta (which I have confirmed) fed from a pad mounted unit substation. The other service is 240V 400A Ungrounded Delta (which I have also confirmed) fed from three cans on a pole outside of the building. But the third (and oldest) service is labeled as "240V Three phase" which clearly only has a single phase and neutral going into the vault. We would prefer to utilize this three phase service (if it is in fact three phase) that is in question, due to its proximity to the location of where the A/C units need to be installed, rather than run some 400-500 feet of conduit/conductors to the confirmed 240V Three phase service.
Any help would be greatly appreciated. Thanks.