Electric Service Upgrade 460/265 to 480/277
Electric Service Upgrade 460/265 to 480/277
(OP)
I am looking into upgrading the electrical service to a commercial building. The building is currently fed from a 460/265v 500kVA service, installed in 1971. The new service will be 480/277 750kVA. All the existing power panels within the building have a voltage rating of 460/265V. Must these panels be replaced with new panels rated at 480/277?






RE: Electric Service Upgrade 460/265 to 480/277
The increase in size of your service will not require you to upgrade your existing distribution panels. You are only changing the main service. If your existing main service is a switchgear type and is rated for the ampacity of the new service than you can probably run the new main service directly into the switchgear. If the switchgear is not rated than you will have to subfeed it from the new main service thru a fused disconnect. You don't to have to change everything. You can integrate your old service in with the new one. This is the cheapest and easiest way but how you spend your money is up to you.
RE: Electric Service Upgrade 460/265 to 480/277
A few things should be verified. If feeder and branch-circuit fuses and/or circuit breakers are labeled/listed for the higher voltage, with switchgear interrupting ratings adequate for the new transformer, that should be acceptable for the proposed work. Conductors should be rated a default 600V. Other transformers, light fixtures, motors and related components should be useable in the ranges listed in ANSI standard C84.1.
Above all, you need concurrence with the AHJ.
RE: Electric Service Upgrade 460/265 to 480/277
RE: Electric Service Upgrade 460/265 to 480/277
440V system voltage is very old dating back to about 1940 or so
Visit
http://www.groban.com/electric.htm
etc. for more info
RE: Electric Service Upgrade 460/265 to 480/277
I have connected 230 v and 240 volts 3ph motors with no problem. The only failure was a old 1 ph refrigrator rated at 240 volts It' compressor did not want to run with 208 v 1 ph voltage. That was back in 1962 and the refrigerator was over 20 years old. we replaced the refrigerator. most new equipment is rated 208v thru 230v 3 ph except for non- U.S.A equipment.
RE: Electric Service Upgrade 460/265 to 480/277
RE: Electric Service Upgrade 460/265 to 480/277
http://search.netscape.com/ns/boomframe.jsp?query=%22440V%22+%2B+%22induction%22+%2B+%22motor%22+%2B+%22westinghouse%22&page=1&offset=0&result_url=redir%3Fsrc%3Dwebsearch%26amp%3BrequestId%3D793dcdfcd68b5e62%26amp%3BclickedItemRank%3D1%26amp%3BuserQuery%3D%2522440V%2522%2B%252B%2B%2522induction%2522%2B%252B%2B%2522motor%2522%2B%252B%2B%2522westinghouse%2522%26amp%3BclickedItemURN%3Dhttp%253A%252F%252Fwww.nelsonmachinery.com%252Fmotors.htm%26amp%3BinvocationType%3D-%26amp%3BfromPage%3DNSCPTop&remove_url=http%3A%2F%2Fwww.nelsonmachinery.com%2Fmotors.htm
e.g.
GE
Westinghouse
etc.
RE: Electric Service Upgrade 460/265 to 480/277
A 3 phase MOTOR that you hook up to that system will likely have a UTILIZATION voltage rating of 460V. This is the design voltage of the windings, and is slightly lower to accomodate any potential voltage drop through the conductors. Lighting loads, because they are typically smaller, are still rated 277V. I have never heard of a 265V rated ballast, and again it would make no sense for a manufacturer to make one. However, a 277V rated ballast would likely work just fine at 265V.
I agree with advidana that the label you see is probably some sort of a quirk from an inspector not truly knowing these issues and making some poor contractor apply this silliness to the panelboard before he would sign off on the job. I have seen it done before. Most good contractors already know that the local inspector is the final authority, right or wrong!
Motors designed outside of the US are sometimes "rerated" for use here by overstating the 415V +/- 20% design voltage as "440" because it still falls into 440 +10%. Most consumers do not realize the difference because we used to call it 440V years ago and many people still do. This is primarily what jbartos found above. My experiance is that these motors will have shorter lifespans and run hotter, especially when the distribution voltage climbs to 500V+ on occasion. If you tried to buy a new motor designed for the US market and wanted a true 440V nameplate rating, you would need to special order it.
"Venditori de oleum-vipera non vigere excordis populi"
RE: Electric Service Upgrade 460/265 to 480/277
jraef’s observations are well supported by chapter 3 in IEEE standard 141-1993, and Donald Beeman’s Industrial Power Systems Handbook, first published in 1955.
RE: Electric Service Upgrade 460/265 to 480/277
See IEEE Std 45
RE: Electric Service Upgrade 460/265 to 480/277
Today the utility opened the transformer enclosure, the secodary voltage of the transformer as per the name plate is 460/265v 3phase. This was the standard voltage provided by the utility when this transformer was installed in 1971. Since all the electrical distribution equipment in the facility is custom made the manufacture rated the panels to match the service. But, although the panel name plate shows the rated voltage at 460/265v the circuit breakers are all rated for 600v and there interupting rating is still adequate for the new service. So, as was suggested in several replies I will review this issue with the AHJ.
RE: Electric Service Upgrade 460/265 to 480/277
RE: Electric Service Upgrade 460/265 to 480/277
Any chance there is a 2½% tap or two that could be changed on the 460V-secondary transfomer? 480/460 = 1.043