4awg big enough from pole to house? 400a panel

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Onlyincali

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Finishing up a 400a house panel (upgrade from 100a). Per my electrician, we had to run 350s from the connection point on roof to the panel which is only 25 feet away. These wires are HUGE compared to what is coming from the pole.

The power company guy who disconnected us said the existing wire from the pole (4awg solid wire, roughly 80ft run) to our house was big enough for our 400a upgrade. Our electrician thinks we need bigger wire from the pole to the house connection point but ultimately said “they should know, they do this all the time. I’ll leave it to him”. Ie: not my problem or job.

Should i make a fuss about this or is the 4awg solid wire truly enough for a 80ft run for a 400a panel?


New wire we ran from connection point on roof to panel
https://i.imgur.com/YJ4IN1T.jpg


And heres the solid wire that goes from the pole to our connection point.
https://i.imgur.com/t9Mv6cI.jpg
 
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You can call the power company and ask and they may react to your request. But if they don't, there is nothing you can do. The worse case scenario is that one of the power company's wires will burn up. This should not effect you other than having a power outage for a few hours. If the neutral burns up, this will cause some damage to plugged in items since the voltage will be unstable, but the power company should reimburse you for damaged items. It's much more likely one of the hots will burn up and this will cause no damage.
 
Onlyincali said:
....The power company guy who disconnected us said the existing wire from the pole (4awg solid wire, roughly 80ft run) to our house was big enough for our 400a upgrade. Our electrician thinks we need bigger wire from the pole to the house connection point but ultimately said “they should know, they do this all the time.
Click to expand...
The POCO has real world data that they use to size wire and transformers. 400A panel does not mean 400A load. My house has a 200A service, and I can't draw more than 80A with everything possible in my house turned on.
 
ActionDave said:
The POCO has real world data that they use to size wire and transformers. 400A panel does not mean 400A load. My house has a 200A service, and I can't draw more than 80A with everything possible in my house turned on.
Click to expand...

And lets not forget that those 80amps are in air- #6 would do it:


https://www.southwire.com/ProductCatalog/XTEInterfaceServlet?contentKey=prodcatsheet34


And remember, thats conservative- they could load that #6 to 110amps and nothing would ever happen.
 
Not trying to be funny or rude, but is there not a RIGHT or WRONG here? Pretty much everything else in electrical work has specific guidelines and sizing requirements but this is the one situation that is a “just do what works till it catches fire” kinda thing?

again, I honestly am not trying to be funny or sarcastic....just a lil confused.


Also, I’d like to make sure I’ll be getting what I’m paying for. I’ve got some hi powered TIG and MIG machines that I’d rather not short on incoming power.

Thanjs again for all the replies!
 
Onlyincali said:
Finishing up a 400a house panel (upgrade from 100a). Per my electrician, we had to run 350s from the connection point on roof to the panel which is only 25 feet away.
Click to expand...
How did the electrician come up with 350 kcmil for a 400 amp service?

Roger
 
Onlyincali said:
Not trying to be funny or rude, but is there not a RIGHT or WRONG here? Pretty much everything else in electrical work has specific guidelines and sizing requirements but this is the one situation that is a “just do what works till it catches fire” kinda thing?

again, I honestly am not trying to be funny or sarcastic....just a lil confused.
Click to expand...

We are not trying to be funny, nor do we want to dismiss your concerns.

Everything in electrical work as covered by the 'national electrical code' has specific requirements, for example the size of wire needed to serve a 100A load. The wire sizing given by the NEC is _very_ conservative, to permit things like a single calculated value to apply to many different installations.

For example, it is well known that conductors in free air can safely carry more current than the same size conductors in a cable buried in thermal insulation. But the NEC gives you one size to work with.

The utilities operate under the 'national electrical safety code', written by a different group for a different audience. The utilities routinely overload things, and yes 'do what works until it catches fire' is sometimes acceptable.

The utility doesn't care how large your panel is; they will size their transformer and service drop based on their experience about the load drawn by your house.

Now, the fact that you have added significant loading is something that you (or your electrician) should call the utility about, because that factor might change their sizing decisions. They may need to replace the service drop or even the distribution transformer.

You should also be on the lookout for problems caused by the new loading. If you are actually loading your service more than previously for extended periods, this will show up in your bill, and might push for larger service drop conductors.

Or you might encounter voltage variation issues when the welders turn on and off. Remember that welders generally operate with a low duty cycle for short periods of time, but can draw high current when under load. This variation in loading can cause variation in the voltage supplied to your home, or even the voltage output of the transformer feeding your home.

Enjoy the new toys.

-Jon
 
Table 310.15(B)(17) (formerly Table 310.17) sez #4 cu = 140A @90C, and there would be two for 1ph, three for 3ph......~RJ~
 
roger said:
How did the electrician come up with 350 kcmil for a 400 amp service?

Roger
Click to expand...

He didn't say it was a 400A service. He said it was a 400A panel, and a 300A load.

Service conductors do not have to have the same rating as the service entrance equipment, under the NEC.

Also, 310.15(B)(7) gives him an extra 63 amps on that 350, if it's copper.
 
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