208V service for a large office building

[greenspark1]

Hi. I have a new large office buildings of about 350k sf. It is roughly a 700' x 300' rectangle. Traditionally we would design this building for 480/277V service. I am investigating if there is a good reason to keep it simple with a 208V service, or a 208V plus a 480V service. 208V would avoid a lot of cost with transformers and a second layer of 208V panels. The only loads that would benefit from 480V would be HVAC and lighting.

A chilled water cooling plant will be located in one corner of the building. Our site is the northeast. Heating will be gas. With the majority of loads being office, lighting, and concentrated HVAC, can 208V be viable? I haven't found much info looking online and curious what other think and have experienced. The buildings are going LEED so energy savings are a factor too. Thanks for any feedback.

 

[charlie b]

It's mostly a pricing decision. My boss has a rule of thumb (that I have not back-checked) that if the 208V service to the building would exceed 2000 amps, then it is likely a 480V service would prove to be more cost-effective.

 

[greenspark1]

Thx for the feedback. Yup, I've only found 'rules of thumb', no hard data. Agreed, it would certainly be a large service, or two. But lots of avoided step-down transformers. Surprised not to find any literature on this. Also interesting to think of potential energy savings outweighing higher first costs.

 

[Strathead]

Thx for the feedback. Yup, I've only found 'rules of thumb', no hard data. Agreed, it would certainly be a large service, or two. But lots of avoided step-down transformers. Surprised not to find any literature on this. Also interesting to think of potential energy savings outweighing higher first costs.

It would take a lot of work to confirm the actual savings, but I think you can depend on the rule of thumb for this one. The savings in copper alone would be phenomenal in a building of this size. It would be different if the building had to be broken in to smaller, compartments requiring high voltage, low voltage transformer set ups for each.

 

[infinity]

Just my 2 cents a building this size would benefit from a 480Y/277 volt service. The savings in wiring the lighting, fans, pumps and A/C loads alone would make it worth using transformers for the 208Y/120 volt loads.

 

[zbang]

Will the PoCo even install a large enough 208/120v service? That might be the deciding factor.