Is this correct

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iwire said:
I am just not as sure as that as you are, which is fine, we all read things differently.

If the installation is like the one in the Mike Holt graphic he has a 312 amp feeder regardless of continuous on non-continuous loads.

The transformers max rated output is 312. (And I already said this :))
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That is the OPs problem: How do you tell a clueless customer that he has a 312 amp feeder for a 400 amp panel?

Customer looks at pic/specs and says " I said I wanted 400 amps and WTH is a feeder? Is that the wire going to the fuse box?"
 
kwired said:
The question is does the customer really know what 400 amps means in the first place? His concern should be how much Kw is available that is what he is going to use.

His second concern should be whether the voltage and number of phases is compatible with equipment he is going to use.

Customer in reality probably knows little about elecrical and is only concerned with information provided by people he trusts (engineers/contractors) that he will be able to use what is installed to power what he needs to run plus what ever future plans he may have.
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Bingo! Customers in general are clueless. Hence, the problem for the OP to answer this one.
 
kwired said:
The question is does the customer really know what 400 amps means in the first place? His concern should be how much Kw is available that is what he is going to use.

His second concern should be whether the voltage and number of phases is compatible with equipment he is going to use.

Customer in reality probably knows little about elecrical and is only concerned with information provided by people he trusts (engineers/contractors) that he will be able to use what is installed to power what he needs to run plus what ever future plans he may have.
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Ok but I'm the customer now!! I don't know my future load but I know that probably the load change a lot from the primary installation to now ,because the business run good and I need to buy new machines , in mi mind I know that when I made my first investment y pay for a 400 amps service that means for me that I can use 400 amps!!! Now after 3 or 4 years I relase that my service at full load can supply only 320 amps. Do you thing that this is right for me?
 
DARUSA said:
Ok but I'm the customer now!! I don't know my future load but I know that probably the load change a lot from the primary installation to now ,because the business run good and I need to buy new machines , in mi mind I know that when I made my first investment y pay for a 400 amps service that means for me that I can use 400 amps!!! Now after 3 or 4 years I relase that my service at full load can supply only 320 amps. Do you thing that this is right for me?
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A 400 amp service can supply 400 amps at full load.

A 208Y/120 feeder supplied from a customer owned transformer can only supply 312 amps.

So the answer to the OPs question is no this is not a 400 amp supply.
 
iwire said:
A 400 amp service can supply 400 amps at full load.

A 208Y/120 feeder supplied from a customer owned transformer can only supply 312 amps.

So the answer to the OPs question is no this is not a 400 amp supply.
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Thats got my vote, as I know sometimes I request a true 400 amp service from our power company under this very reason, as the customer plans to expand, and I install all 400 amp continuous rated equipment, the POCO will supply there (under rated) version of a 400 amp service, I think with a 75kva tranny and 4/0 Al, conductors (they can get away with it), but the service is rated 400 amp, and any confusion is on the POCO, now if this building requires 480/277 loads also will open a whole another can of worms, as then the service point moves to the 480 volt side.

So I agree that we must meet the request on our side of the service point if we claim to install a certin size service.
 
iwire said:
A 400 amp service can supply 400 amps at full load.

A 208Y/120 feeder supplied from a customer owned transformer can only supply 312 amps.

So the answer to the OPs question is no this is not a 400 amp supply.
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It just doesn't get any clearer than that.
 
is this correct

is this correct

I shoud have never told the customer that his 400A service was really 312A because they insisted that techanically it was not a 400A service like the lease showed. He's right, do I installed a 150KVA and fuse down to meet a true 400A or do I stand my ground and say that a 400a service is really 312A.
 
Why don't you really confuse them and tell them that they have a service that is capable of delivering 312 amps "per leg" which would furnish them 936 amps of single phase load. The term "400 amp service" means nothing. Technically "service" as defined by the NEC is the point of attachment from the power company. What is a 400 amp service? 400 amp service conductors? a 400 amp transformer? a 400 amp disconnect switch? This seems to be a ridiculous argument over what may happen someday. It is just as likely that the company will be out-of-business as it is that they will need additional power. It is very hard to future proof an installation and we can play with words all day. The customer may not care about continuous and non-continuous but it is all part of the calculation
 
This is very interesting and some good points were made. I can't seem to be able to pin down a definate nay or yeah about the service requirement.

Might the customer be appeased in the fact that there is adequate system capacity for their current and future needs if applicable?

Please excuse the ignorance but what is their rate structure?


(As I type the question I just get the feeling I am really asking a dumb one, oh well)
:cool:
 
DARUSA said:
Ok but I'm the customer now!! I don't know my future load but I know that probably the load change a lot from the primary installation to now ,because the business run good and I need to buy new machines , in mi mind I know that when I made my first investment y pay for a 400 amps service that means for me that I can use 400 amps!!! Now after 3 or 4 years I relase that my service at full load can supply only 320 amps. Do you thing that this is right for me?
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Like I said before does customer really know what 400 amps means. He is going to use and be billed for to use Kilowatt-hours. If his current demand plus any known future demand can be met there is no problem. How do you size for future loads if you don't know what they are? What if he ends up needing 1200 amps at current voltage and phase in future?

If you bring him 4 - 100 amp feeders supplied by transformer(s) capable of delivering the full 400 amps he will have what he wants but yet he may not depending on what he needs to power.

Bring him 600 amps @ 120/240 single phase and he will have about the same KW capability but will not be able to run three phase loads.
 
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They sold me a 44.1" flat screen tv as a 55" inch screen. Its called a 55" CLASS TV.

What we consider a 400 amp service is a 400 amp service by industry standards, A residential service with 2/0 is still a 200 amp service.
 
iwire said:
A 400 amp service can supply 400 amps at full load.

A 208Y/120 feeder supplied from a customer owned transformer can only supply 312 amps.

So the answer to the OPs question is no this is not a 400 amp supply.
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I agree with that.
 
is this correct

is this correct

What started this, my boss was told by the landlord that the new tenant moving into the warehouse is requesting a 400A service 480v/277. The warehouse is supplied by a 800A service. It was one tenant. Now it was two separate tenant both receiving 400A services. Now picture this, the 800A service is really 640Amps. And your supplying two tenants with 400A services. Are they getting what they pay for? And one tenant is occuping about 20% more sq. footage.
 
jrvazzer said:
What started this, my boss was told by the landlord that the new tenant moving into the warehouse is requesting a 400A service 480v/277.....
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This is very different from what you originally posted:

...clients requested in their lease 400A 120/208v 3ph, 4w service for their facility....
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A 480 Volt 400 Amp service can yield up to 333kVA.

A 208/120 Volt 400 Amp service will give you only 144 kVA.

Which is it that you want here?
 
IMO, if the service has a conductor capable of handling 400 amps then it is a 400 amp service. The transformer may only be rated 312 or whatever it was but the panel still has the ability of 400 amps-- provided there is room to add more breakers. The service is one thing but the feeder is another.
 
How much load can be applied without opening an overcurrent device? Just because the transformer is only rated 312 amps doesn't mean it won't attempt to deliver 400 if that is what is connected to it. Voltage drop and excess heating will be a consequence and after enough time passes by can result in insulation failure.
 
jrvazzer said:
is this correct 400A 480v, 3ph
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I have no idea. Your original post was concerning whether a transformer was sufficient to provide 400 Amps @ 208 Volts.

Now, you are asking about 400 Amps @ 480 Volts.

Completely different animal.

Are you supposed to supply only 400 Amps @ 480 Volts to the leased space, and let the tenant take it from there? If so, then all the discussions about a 208 Volt transformer are a moot point.
 
One might make an argument that the transformer is capable of providing 400A but with reduced lifespan. Add a fan and it might not even care. Call the manufacturer's tech support line and talk to someone in the know.

it's kind of a small transformer to add a fan kit to, but they might have one.
 
Is this correct

kbsparky said:
I have no idea. Your original post was concerning whether a transformer was sufficient to provide 400 Amps @ 208 Volts.

Now, you are asking about 400 Amps @ 480 Volts.

Completely different animal.

Are you supposed to supply only 400 Amps @ 480 Volts to the leased space, and let the tenant take it from there? If so, then all the discussions about a 208 Volt transformer are a moot point.
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Your absolutely right 400 amps 120/208v sorry for the confusion. Got carried away. Looking at all the comments can I conclude that the Tenant visually see a 400A panel in reality and not knowingly be getting 320A availability.
 
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