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  1. Re: any potential violation questions, if I'm not...

    Re: any potential violation questions, if I'm not mistaken, most all commercial workstations, at least in the US can only have up to 13 outlets on one circuit max. I did a spreadsheet a few years...
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    Did this not include the inductive motor current...

    Did this not include the inductive motor current for the cooling fan?

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    What a great conversation. I.e. The more you...

    What a great conversation. I.e. The more you know, the more you don't know!

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    Well if you're the one that's going to be there 5...

    Well if you're the one that's going to be there 5 years from now as mentioned by others I would make the case to do the upgrade and change the drawings although we know the customer doesn't always...
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    So if you have existing Breakers and existing...

    So if you have existing Breakers and existing feeders for the smaller Transformer and are considering putting in the 75, you would be required to put in the properly sized breaker and wire for the...
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    Here's a quick xref that covers the breaker...

    Here's a quick xref that covers the breaker sizing.

    When installing a transformer, use the transformer secondary rules in 240.21(C)(1) through (C)(6). 


    Where installed in accordance with one...
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    Correct, human design error, we had a MDF or IDF...

    Correct, human design error, we had a MDF or IDF closet where the electrical engineer put a 480/120/208vac 300 KVA xfmr adjacent side of this cable distribution closet within 2' where the magnetic...
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    Design choice, unless you have separate panels...

    Design choice, unless you have separate panels feeding the computer outlets with a Priority Generator Power or UPS circuit. We had 800+ workstations with three circuits, two normal, one or Computer...
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    Yes, totally agree, however, we had critical...

    Yes, totally agree, however, we had critical operations not only for the Datacenter but all 1750 people protected by one-ups circuit per office/per cubicle which included all energy management...
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    Sounds normal for totally unloaded, the property...

    Sounds normal for totally unloaded, the property I was referring to had a minimum running load 24/7 of 1000 KW. Data center load plus cooling. So the building was never unloaded. I'm sure with no...
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    I had a large property where the running loads on...

    I had a large property where the running loads on the building during the day with 1700+ people, started bringing down the voltage on the secondary side of our 16kv/480v 2500 KVA Xfmr. As far down as...
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    That's a long run, is this in a commercial area,...

    That's a long run, is this in a commercial area, large residential? It might be cheaper depending on the clients needs to install a new service entrance and pole mounted xfmr closer to the load. If...
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    Correct, per NEC 230.95 as quoted, The NEC...

    Correct, per NEC 230.95 as quoted,
    The NEC requires ground fault protection for 480/277V, 3-phase, 4-wire, wye-connected services rated 1,000A or more, but it’s optional in other configurations...
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    This should help answer some questions....

    This should help answer some questions. https://www.csemag.com/articles/choosing-between-3-pole-and-4-pole-transfer-switches/

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    Okay this thread might be getting a little old or...

    Okay this thread might be getting a little old or redundant but when you say you have three phase 240 volt on your primary and you want to feed a 3-phase 480 volt load how do you obtain that or am I...
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    It's just something I experienced adding new 200...

    It's just something I experienced adding new 200 KVA power distribution units to existing UPS systems critical output bus it was a standard that we used to pre energized on a non-critical 10000 day I...
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    There is always a load when you turn on any...

    There is always a load when you turn on any Transformer especially large ones depends on the level of saturation the Curve and the last time it was started up or energized so when connecting new...
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    It appears that they might have used the...

    It appears that they might have used the generator for 120volt loads, where the amps are up around 360+

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    Correct, a typical 3phase generator at 75 KVA or...

    Correct, a typical 3phase generator at 75 KVA or 60 KW is 208.4 amps @ three phase, the 400 amp breaker as you mentioned sounds like it was used for a special purpose like inrush current, but a 225 a...
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    You can calculate all you want, normally, I would...

    You can calculate all you want, normally, I would allways do a before and after for total load in amps. Knowing that heaters are normally a PF of 1, and the remaining unbalanced loads will also...
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    I've engineered a transfer inhibit switch on an...

    I've engineered a transfer inhibit switch on an ATS before, in my case, specifically, the ATS that was feeding the critical UPS and Battery systems including the maintenance bypass cabinet.

    I've...
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    When it's on a panel that's servicing critical...

    When it's on a panel that's servicing critical load with a main and sub main, all PDUs have 10AIC,

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    It is typical to have the Mains higher, regular...

    It is typical to have the Mains higher, regular load distribution breakers for power, 120/240 and 277 circuits at the 22k then critical distribution breakers inside let's say a PDU or UPS...
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    Assuming the air outlets are facing each other,...

    Assuming the air outlets are facing each other, I've seen the use of upward draft directional housings or addons. With drains and protective grates.

    If in or near a residential area, there could...
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    There are many variables with PF Cap maintenance...

    There are many variables with PF Cap maintenance and usually tied to the power supplied equipment, I.e. UPMs, Static UPS, where the choke transformer losses are suceptable to increases in...
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