225A Residential Farm Type Meter Main W/225A Main Breaker

[tryinghard]

Agree on the fuse size unless I decide on a smaller feeder. The sub is stock SIEMENS P5470B1225CU, and panelboards are simply specked and built as needed normally non-residential but certainly compliant and not a whole lot more money

 

[david]

350s are good for 300 amp residential. Why waste the money on 250 amp fuses?

I may be missing something but i am under 2008 NEC How is 350 Alum from a main distribution to a single family dwelling good for 300 amp

Unless we ignore the available breakers at the property line, would you be able to take advantage of any residential application to the ampacity tables

 

[Jamesco]

I may be missing something but i am under 2008 NEC How is 350 Alum from a main distribution to a single family dwelling good for 300 amp

Unless we ignore the available breakers at the property line, would you be able to take advantage of any residential application to the ampacity tables

2014 NEC 310.15(B)(7) (1) & (2)
https://www.jadelearning.com/jadelearning/thejunctionbox/applying-nec-310-15b7/

Might be fine for a short run. Here we are talking about a 300ft run.

NEC is bare minimum electrical safety standards. Bare minimum.

NEC Article 90

NEC 90.1 has four subdivisions:

• (A) says the purpose of the NEC is the practical safeguarding of people and property "from hazards arising from the use of electricity."
• (B) distinguishes from the adequacy concept (provisions necessary for safety) and other concepts. The Code is a minimum standard. Further effort may be required for an installation to be efficient, convenient, or adequate for good service or future expansion. This is a fundamental concept upon which many Code disagreements arise. The Code is not a target you’d like to hit. It is the minimum you can do.
• (C) clearly states the Code is not intended to be a design specification or instruction manual.

• http://www.codebookcity.com/codearticles/nec/necarticle090.htm

 

[david]

2014 NEC 310.15(B)(7) (1) & (2)
https://www.jadelearning.com/jadelearning/thejunctionbox/applying-nec-310-15b7/

I see so in this application you do two load calculations one for the feeder to the dwelling and one for the service including the loads at the property line

 

[Jamesco]

Agree on the fuse size unless I decide on a smaller feeder. The sub is stock SIEMENS P5470B1225CU, and panelboards are simply specked and built as needed normally non-residential but certainly compliant and not a whole lot more money

tryinghard,

Assuming you figured the total connected load and you figured a 225 main breaker panel will meet the customers needs + a fudge factor to cover your butt + some room for future added load/s expansion.

So,... 80% of 225 amp = 180 amps. You can safely load the panel at 180 amps for 3 hour or more without the main 225 amp breaker over heating. From your load calculations there will not be any problem with that happening, correct?

VD load calculators.

http://www.calculator.net/voltage-drop-calculator.html

http://www.southwire.com/support/voltage-drop-calculator.htm

http://www.nooutage.com/vdrop.htm

JMHO, I would not install a smaller feeder wire than the 350 AL you mentioned earlier. I also would not use an OCPD smaller than the 250 amp you suggested. (350 AL is good for 250 amps.) (What is the max lug wire size on the electrical panel 225 amp main breaker?)

IF I were installing a 400 amp meter setting I would at least size the load feeders for the 320 amp max rating. Forgetting the 300ft distance of the run, the conductors would be 600 AL. (600 AL is good for 340 amps). Unless local code doesn't allow it, you could check NEC for reducing the size of the neutral conductor.

At the house set a small 400 amp breaker panel. You only need to install, at present, a 225 amp breaker for the 225 amp panel.

I keep going back to your post where you said you come up with a 210 amp calculated load.
80% of 225 amp = 180 amps.

If it were me I would set two 200 amp panels. Fed from 2 - 200 amp breakers in the outside 400 panel.

Jim

 

[electrofelon]

What is the OP's total calculated load? Is it 210 amps? I am not sure.
If it is 210 amps would you would recommend feeding it from a 225 amp breaker?

Yes, maybe even a 200. NEC calcs are super bloated for resi. Guarantee that never gets over 120 amps. Ever. Any wire or ocpd over 225, or VD calc using over 100 s just a total waste.

Will that meet NEC code. How will he protect the feeder wire?
The main service disconnect will need to be at the property line pole with the meter.

With the disco next at the house, the line coming in is service entrance conductors, not a feeder. There is no restriction on its length. Protection is provided by the device it terminates on.

 

[Jamesco]

Originally Posted by Jamesco

What is the OP's total calculated load? Is it 210 amps? I am not sure.
If it is 210 amps would you would recommend feeding it from a 225 amp breaker?

electrofelon Said:
Yes, maybe even a 200. NEC calcs are super bloated for resi. Guarantee that never gets over 120 amps. Ever. Any wire or ocpd over 225, or VD calc using over 100 s just a total waste.

You could be right. I don't have the info the OP has. I can only go by what he has posted.

How will he protect the feeder wire?
The main service disconnect will need to be at the property line pole with the meter.

electrofelon Said:
With the disco next at the house, the line coming in is service entrance conductors, not a feeder. There is no restriction on its length. Protection is provided by the device it terminates on.

Remember the Power Company's meter is 300ft away at the property line.
I'll bet you a dollar to donuts the Utility Power Company will never hook up if there is not an OCPD at the meter site.

Here the OP could just chime in and settle it. I'm sure he knows what the power company allows and doesn't allow.

 

[Jamesco]

electrofelon Said:
With the disco next at the house, the line coming in is service entrance conductors, not a feeder. There is no restriction on its length. Protection is provided by the device it terminates on.

Protection is provided by the device it terminates on.

That's not going to protect the ungrounded conductors from a Line to Line fault or a Line to ground, ground fault event.
Doing as you suggested the HV fuse on the primary side of the utility company's power transformer is the only protection. Secondary of the transformer overloads, that causes the primary of the transformer to overload, and hopefully the HV fuse blows.

 

[tryinghard]

225A Residential Farm Type Meter Main W/225A Main Breaker

You could be right. I don't have the info the OP has. I can only go by what he has posted.






Remember the Power Company's meter is 300ft away at the property line.
I'll bet you a dollar to donuts the Utility Power Company will never hook up if there is not an OCPD at the meter site.

Here the OP could just chime in and settle it. I'm sure he knows what the power company allows and doesn't allow.

The OCPD (service disconnect) can be a fused disconnect nippled to the 320 meter base UG term combo, the SD will be labeled “service rated”, although this is not resolved yet but is likely, it will have 300a fuses, feeding 350s AL to a main beaker panelboard 300’ downstream

 

[electrofelon]

That's not going to protect the ungrounded conductors from a Line to Line fault or a Line to ground, ground fault event.
Doing as you suggested the HV fuse on the primary side of the utility company's power transformer is the only protection. Secondary of the transformer overloads, that causes the primary of the transformer to overload, and hopefully the HV fuse blows.

But you can say that about any and every service conductor. If putting the disconnect/OCPD closer to the supply side makes you sleep cozy and snuggly at night have at it. I'm not writing the checks for this job, I'm just saying what code says

Also for completeness, see 240.21 (B) which allows for outside feeder taps of unlimted length without over current protection on the supply side.

 

[tryinghard]

Why install at 250 amp over current protection and only use a 225A buss panel?

Talk to your supply house about getting a 400 meter main and have the factory install a 250 amp breaker instead of the 400. I have done this before. I believe the last time it was a B-Line (Cooper) meter main. Even if the factory can't do it or in the time you need it done you could replace the 400 amp breaker yourself.

Thanks Curt, if I go with one feeder this’ll be worth pursuing, I think Milbank makes a 400A meter main

 

[tryinghard]

tryinghard,

Assuming you figured the total connected load and you figured a 225 main breaker panel will meet the customers needs + a fudge factor to cover your butt + some room for future added load/s expansion.

...

I keep going back to your post where you said you come up with a 210 amp calculated load.
80% of 225 amp = 180 amps.

If it were me I would set two 200 amp panels. Fed from 2 - 200 amp breakers in the outside 400 panel.

Jim

Jim thanks for your input. I agree with many here that an article 220 calc is always conservitivy high but it is required to size the service and it is an acceptable model, certainly the proof is in the puttin and the result of real watt hours over a year with 3 highest months proves usage on loads that are so sporadic and periodic as a house. I used article 220s example D2.b and with this model no other factoring is needed in other words the result can be served or fed at minumum. Voltage drop residentially is more an issue with 120v branch, the calculated load will likely never happen and if it does can cause more than 3% VD with no ill affect on a 240V circuit because UL appliances are rated much less (utilization or NEMA around 208V - notice Table 1 “National Steady State Voltage Regulation Standards”). If I use one feeder I plan on applying Table 310.15.B.7, the feeders OCPD will be the service disconnect and the panelboard at the house will be amply sized above the calculated load, if I go with 225A main breaker sub this’ll be the minimum and factory available othwise I’ll use a main breaker panelboard. I agree to use the 400A 2-200 but this will cost substantially more with 2 300’ feeders & sub panels rather than one although Im currently comparing the two options and will know soon. Thanks again

 

[curt swartz]

Forget about running 2 feeders to the dwelling. Violation of 225.30.

 

[electrofelon]

Forget about running 2 feeders to the dwelling. Violation of 225.30.

Right, but one could do it with service conductors 230.40 exception #2 (I know you know this, stating for others).

 

[tryinghard]

Forget about running 2 feeders to the dwelling. Violation of 225.30.

Woops, that took care of that. I think this exists to eliminate possible mixing branch and neutrals. My case does not fit but I notice 225.30.C

 

[Jamesco]

Forget about running 2 feeders to the dwelling. Violation of 225.30.

He wouldn't need 2 feeders to feed 2 separately fed panels in the dwelling.
(see my post 25)

I assume the power company's required meter sequence is, meter, switch, fuse.

One possible wiring method used.
Meter >>> Service Main OCPD >>> 3 wire + EGC feeder to house >>> 400 amp electrical panel on the outside of house with, 2 - 2P 240 breakers, with an insulated neutral buss/bar and a bonded to metal enclosure equipment ground bar. (This panel could also be mounted inside the house) >>> One of the two 2P breakers will feed one panel and the other 2P will feed the other. (The OP may find he will save money on branch circuit wiring with the placement of the two panels in the 3570sq ft house, opposed to installing only one panel).

Maybe over kill, but I don't think so, the minimum feeder wire size I would run would be 600 AL. I would look at derating the size of the neutral as allowed by code.
Service Main Breaker at the meter 2P 350 amp.

tryinghard said: Post #4
Thanks all, interesting thing is the residential 320 doesn’t use CTs nor does the 2-200 the load routes through the meter. The calc might have a mistake but not likely way off, the customer wants the meter main remote at the property line about 300’ from the house, and we’d like to pull one feeder rather than two. The calc method used is Art 220 and Annex D2.a example method, this is a large house: 3,570 sq ft, 2 kitchens (with ranges, dish/garbs, built in micros), 2 laundry’s & dryers, 2 ACs (4.5 ton & 1 ton), 1 vehicle charger (5.4kva), 1 extra freezer, I come up with 25.044 Kva general load and 49.787 kva

And what if the owner later down the road decides to add, .....

Jim

 

[tryinghard]

He wouldn't need 2 feeders to feed 2 separately fed panels in the dwelling.
(see my post 25)

I assume the power company's required meter sequence is, meter, switch, fuse.

One possible wiring method used.
Meter >>> Service Main OCPD >>> 3 wire + EGC feeder to house >>> 400 amp electrical panel on the outside of house with, 2 - 2P 240 breakers, with an insulated neutral buss/bar and a bonded to metal enclosure equipment ground bar. (This panel could also be mounted inside the house) >>> One of the two 2P breakers will feed one panel and the other 2P will feed the other. (The OP may find he will save money on branch circuit wiring with the placement of the two panels in the 3570sq ft house, opposed to installing only one panel).

Maybe over kill, but I don't think so, the minimum feeder wire size I would run would be 600 AL. I would look at derating the size of the neutral as allowed by code.
Service Main Breaker at the meter 2P 350 amp.



And what if the owner later down the road decides to add, .....

Jim

Plenty of room to add with the current 210a calc, hence the reason for 300a feeder to panelboard, although I would not feed over 350s. Your 400a 2-200 does work we just don’t need the additional sub panel

 

[tryinghard]

He wouldn't need 2 feeders to feed 2 separately fed panels in the dwelling.
(see my post 25)

Maybe over kill, but I don't think so, the minimum feeder wire size I would run would be 600 AL. I would look at derating the size of the neutral as allowed by code.

Jim

Jim, over sizing is not wrong but does cost more and is not necessarily safer.
We only need to serve/feed the calculated load, this is not only compliant it is also safe, professional...
Calculated load is not true power, it’s really theoretical, it’s the high end of a possible load and if it actually happens it will only likely for a very short time.
To view VD is fine and a good gauge but it’s results from a calculated load of over 3% are not dangerous or damaging (probably why it’s not code just a FPN). Thanks again!