208V vs. 277V Service in Commercial Buildings 1

[grosshennig]

I would like to better understand how the electrical service of commercial buildings looks like? (office buildings, warehouses, machine shops, ...)
To my understanding there are mainly two three-phase grid situations: 208V WYE and 480V WYE. (600V in Canada, Delta services are slowly going away)

What is the most common voltage/electrical service coming from the utility? (maybe by application or segment as listed above)
If it is 277V/480V, there must be a transformer that feeds the receptacles. Or do you get both 208V and 277V from the utility at the same time?

Any help would be appreciated, even it is a link or a good book to read.

 

[rbulsara]

It is not about reading books but economics and local standards.

480Y/277V is common in the USA. 600Y/347V is in Canada. There are many other voltages that exist in both places, but many are for some historical reasons and some may be application driven or local conditions.

208/120V is still needed for convenience receptacles and appliances, computers etc. So if the three phase load is minimal it makes sense to just go with 208Y/120 service. For any significant 3 phase loads, 480Y/277 makes economical sense. But again it depends on actual applications. A large non-air conditioned machine shop with a number of small motor loads may be a candidate for just 208Y/120V service. Air-conditioned commercial spaces changes the equation.

Commercial lighting is more economical at higher voltages 277 or 347V.

Utility co.s will provide whatever service you want, as long as you justify it and pay for it.

Location may play a role. Choices of voltages in a remote area may be different than those in an downtown area of a large city.



Rafiq Bulsara

http://www.srengineersct.com

 

[waross]

A large mall in Canada may have a 600/347V service and use 600 for the mechanical rooms. 347V will be used for lighting under control of the mall such as corridors, public areas and parking areas. Transformers will supply 120/208V to the tenants. In the US that would be 480/277V instead of 600/347V

Bill
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"Why not the best?"
Jimmy Carter