400 amp service vs. 600 amp service

[Jaguar Fan]

For a custom home where we have not yet broken ground (plans are being submitted to the city), the engineer has calculated 356 amps maximum load (including 20 amp for future expansion per NEC article 220.5), and recommends 400 amp service minimum.

I thought perhaps I should specify 600 amp service for future expansion just in case. The entire package has not yet gone out to an electrical sub for bid, but the architect asked how much extra for 600 amp service vs. 400.

It is an extra $3,000.

Does that seem like a reasonable up-charge?

Is it silly for me to think of upgrading to 600 just in case?

Thanks
JF

 

[mrb]

it will cost you alot more than that to upgade later and with a 400 amp you only have 10% headroom so I would do it...

 

[Gregishome]

That must be what, a 25,000 sq. ft + home ?

 

[Gooch]

around here that installing a 600 vs a 400 amp service would be well over $3k. Here anything over 400 amp requires a CT cabinet and meter and gets very expensive.

mrb is right, to change it later could be rediculous.

how big of a house are you building, 400 amps is alot! is it all electric?

are you doing a Geo setup? alot of utilities will allow a second meter that would be for your HVAC equipment and is billed at a lower rate. I've done 10,000 sq foot homes that didn't need a 400 amp service.

 

[Gary S]

Pity the day you actually use that 600 amps and have to pay the electric bill.

 

[theoldwizard1]

The entire package has not yet gone out to an electrical sub for bid, but the architect asked how much extra for 600 amp service vs. 400.

It is an extra $3,000.

Does that seem like a reasonable up-charge?

That might be a reasonable charge for the inside your building, but you need to check what your power company says.

The typical new home power has a 200-250 amp feed. Anything over that is likely going to cost more. At 400 or 600 amp, they might have to install a new transformer and want to pass that cost on to you !

600 A overkill ? IMHO YES, unless you think you might be installing a large metal shop with welder, plasma cutter, lathe, bridgeport, etc. I typical "average" shop, which might have a couple of those machine, but only used 1 at a time, would be comfortable with 100 amp feed.

Remember, your architect is spec'ing the MAX, which would almost certainly never occur and can exceed the main.. What size mains breakers are specified in the electrical sub-contractors bid package ?

 

[SixStringMadness]

It is an extra $3,000.

Does that seem like a reasonable up-charge?

Is it silly for me to think of upgrading to 600 just in case?

Thanks
JF

Reasonable? $3000 upcharge on what? What is the starting point?

Silly? I wouldn't say silly, but I believe it's over the top. A calculated load is not necessarily what you'll be clicking along at. The most current drawing items in your house are (and they are circuit ratings, whats roughly used to calculate your total, but not actual draws):
Oven/stove: 50 AMPS
HVAC: 60 AMPS (x2 or more if a bigger house)
Water Heater: 30 AMPS
Dryer: 30 AMPS
the rest are plugs and lights

What else do you have going on?

If you want 200 more AMPS for a shop, consider a second service connection maybe.

It would be good to have a little more information to really give you some solid answers.

 

[79firebird]

400 should be fine. At work we have 400 amps, 10 hihbay lights 2 10hp compressors band booth fan all eclectric heat for 10 offices upstars lift etc. Ive thrown a meter on it most we have pulled at a single like was 300 amps

This is also single phase. for 600 amps may as well go there phase 400 amp service if you can get it

 

[Aceman]

It is an extra $3,000.

Does that seem like a reasonable up-charge?

Is it silly for me to think of upgrading to 600 just in case?

I'd let the person paying the bill decide....

 

[Tscott]

Most power companies will set a standard meter up to a 400A service. Anything over that typically requires the service to be CT metered which can get spendy. Depending on the location of the home, a new transformer may need to set, but probably not unless what is there is super small.

Personally I think a 600A service is way overkill. When you look at the loads in the building you cannot just add all the amp draw numbers up to get your service size, it will be way too large. You must remember to diversify your loads as they will never run all at the same time. A safe rule of thumb we use here is around a 50% diversification, i.e. only 50% of the load will be on at any one time as a worst case scenario. I have a 200A service in my house and I would be willing to bet it has never seen more than 50A at any one time.

Tom

 

[DekeT]

Are you doing electric heating? My "engineer" and the "architect". Maybe your engineer and architect need to give you better advice.

 

[Stuart in MN]

A 600 amp service for a residence is very unusual, but everyone is making assumptions without knowing the whole story...without seeing the plans, second guessing the engineer's calculations serves no purpose.

 

[ForceFed70]

Around here, a standard new home has a 125A service if heating with gas. If heating with electricity, they install a 200A service.

400A is rare and would involve a very large luxary home.

600A for a residence is almost unheard of.

What type of home is this? Is the designer simply adding up all of the individual circuits to come up with a total draw? If so, that's not the industry standard way of calculating load as having all circuits at 100% capacity simply will not happen.

 

[bullington]

Our property is set up where we have 200 Amp for the house and 200 Amp for the detached shop. I have never ran into an issue at either place. I get two bills, but they are sent in the same envelope.

It was less expensive to set it up this way.

 

[browntown]

Get three phase! I am constantly amazed at the professional equipment on Craigslist for super cheap because they're three-phase. If it is available, I'd think about it. I think of all the cheap industrial drill presses, lathes, compressors, etc that sit on CL for months at basement prices. Might pay off to pull in the service for a shop and then have a separate 400amp singlephase for the rest of the house and out-buildings.

 

[Tscott]

I will also add, that you may decide to install a 600A service, but depending on how the power company sizes your transformer and service wire you may end up with a 600A meter install with the service wires sized for a 300A or 400A install. The power company is not governed by NEC and can size the service wire to their expected load. So you still may end up with 400A of capability with a 600A service.

Tom

 

[W-Cummins]

I will also add, that you may decide to install a 600A service, but depending on how the power company sizes your transformer and service wire you may end up with a 600A meter install with the service wires sized for a 300A or 400A install. The power company is not governed by NEC and can size the service wire to their expected load. So you still may end up with 400A of capability with a 600A service.

Tom

More likely even smaller! Around here here they use a 12 or 15kva can for a 200 amp service and know all too well that it's NEVER going to be overloaded! I would be really surprised to see more than a 75kva feed for that 600 amp service.

BTW
If you really did pull, say 300 amps continuous, that $3k up-rate charge would be chump change, because at 10 cents per kwh you would be burning $5k per month!

William...

 

[Todd.Brock]

Yeah, so what the hell ya doin in there anyway???600a service whoa...

 

[StaggeringGoat]

And I about had a heart attack this month when I got the bill for my (3 phase) 125 amp service.

If you're really using that much power I agree, you should look into 3 phase if it's available.

 

[mm08822]

The NEC has a standard calculation (found in article 220.80) which is based upon square footage of the home, small appliance loads, heating, cooling loads, etc. These loads have a diversity factor applied to them because everything in the home will not be running at the same time – an easy example is heating and cooling. This calculation will provide you with a load to establish the minimum size service to meet code. You will round it up to the next standard size service anyway. You can always increase above it, but at least you know where you are starting from. The town might want to see this calculation when the plans are submitted anyway.

Without having the particular details about the home – sq ft, gas/electric, etc., there is no safe answer. Have the engineer provide you his calculations and the information he used to get to that number. Hopefully he has made a calculation based upon article 220.80 to obtain the minimum required – but let him tell you that. Once you get the details of his answer, tell him to show/make the calculations based upon 220.80. It takes about 15 minutes to do this - including a coffee break. (We’re talking about 1 sheet of paper.)

If you can provide the house details, I could crank out a quick number for you.

 

[bad_idea]

one more observer interested to know why you need 600A. Hell, I am sure there are a couple treehuggers somewhere crying at the thought of you using 600A! (I am not one of them BTW)

 

[DekeT]

The OP is actually Tony Stark. Like I said before and what others have mentioned is you need a better explanation for 600 amps with your "architect" and "engineer".

 

[79firebird]

ok heres what he sead
the entire package has not yet gone out to an electrical sub for bid, but the architect asked how much extra for 600 amp service vs. 400.
It is an extra $3,000.
It will be more power co may even say no. chances are it will be way more then that as going from a 400- 600 prices more then dubble. for 600 you will need to build a room for all the equitment and transformer. your looking into atleast minum 10 grand by the time your done upgradeing

 

[waggie]

Get three phase! I am constantly amazed at the professional equipment on Craigslist for super cheap because they're three-phase. If it is available, I'd think about it. I think of all the cheap industrial drill presses, lathes, compressors, etc that sit on CL for months at basement prices. Might pay off to pull in the service for a shop and then have a separate 400amp singlephase for the rest of the house and out-buildings.

NOW YOU DONE IT!! letting the 3 phase secret out.

 

[jvitez]

FWIW, I spec'd 400 amp service for my home as I wanted to have the capacity for electric heat in the garage and possibly a detached shop. We're in Siberia, AKA the Canadian prairies. Our house is geothermally heated with electric back up, two electric water heaters, electric oven, food steamer, shower steam unit. We're hooked up to NG, but we only use it for one NG fireplace and a gas cook top. House is 3500 sq ft with full basement, so 6000 heated sq ft, super EE construction called R2000 (a Canadian standard), with R60 ceilings, spray foamed 2x6 walls for R33, R24 fibreglass batts in the basement. However, the electrical contractor said his load calc using the Canadian Electrical Code came in under 200 amps.


So, to calculate 365 amps we're missing some important details, like house size, an electrically heated pool, etc. 400 amps at 240V single phase is 96,000 watts. Yikes! I can't imagine what would require that amount of power draw for a residence.

Tonk Stark: