Hello again oldandworn
It appears as though you have done your homework regarding the backup generator and transfer switch and are planning on a safe installation.
Regarding the 400 amp versus 200 amp service. In my end of the world and probably yours as well 200 amps is the largest self contained meter that is available. That means that all of the current (amps) being used go through the wiring and circuitry in the meter.
For a 400 amp service the wiring would have to be too large to be self contained within the meter itself. Therefore,something called instrument metering is used. That requires additional components called current transformers(CT's) which all the current flows through and a proportionate but much smaller current flows from the ct's through smaller wires to a special meter which registers your electrical consumption. That is just 1 of the reasons for added expense with a 400 amp service.
Is electric heat and air conditioning common in your area? That would explain why 400 amp services are popular for acerages and larger homes.
In my previous post I mentioned that utilities charge more for larger services because all of there equipment must be larger as well. You stated the equipment serving you is a minimum size that would accomodate much larger than 1 200 amp service. I was also refering to all of the utilities equipment back through the main line,back through the sub stations and back to the generator itself. 1 customer of course doesn't make a difference however they must be able to supply your 400 amp service as well as well as the thousands of others at any given time because the potential is there. So if every customer were to overbuild thier system,the utility must overbuild thiers and you can see how that could impact the utilities bottom line which of course would be passed on to the customers.
I hope that makes sense. I am just trying to explain to you why an electric utility might be concerned about the size of your service and make you pay in some shape manner or form. Whether it be the original contract for power installation or your monthly bills or a combination of those 2.
Once again I will say that the info I have provided pertains to my area and your milage may vary.
Thanks skipper, I do electrical engineering and testing (fiber optic communications) for my day job which doesn’t mean I’m an electrician but it’s kinda the same except the wires and watts are much bigger with electrical work.
Around here CT’s don’t start until you go beyond a 400 amp service. When I say 400 amp it’s really 320 continuous 400 peak.
I would think the local utility would factor in the total customer usage on their system but the engineer is treating this decision very lightly and here is how that conversation went. Make sure you run 4” conduit between the transformer and meter and call us before we come out if you decide on a 400 amp service so we can bring larger wire. And this conversation was for the 2 separate transformers so if I really wanted to be an energy pig I could end up with an 800 amp burden on their system.
The small all electric house I’m living in now (no natural gas available) is about normal in the Washington/Baltimore area for a house with no gas.
200 amp service:
100 amp breaker to the indoor heat pump air handler for the backup and emergency resistance heat.
40 amp breaker to the outside heat pump compressor.
40 amp to stove
40 amp to oven
30 amp to water heater
30 amp to cloths dryer
15 and 20 amp circuits to the rest of the house.
I have never tripped the 200 amp main but here is an example of the draws that have occurred many times. Wifey is cooking and has the oven and stove going. Water heater kicks in, heat pump goes into defrost mode (every 90 minutes when cold out) which turns the high wattage backup heat on, outdoor unit is still running in A/C mode for defrost. It’s possible if my MIG welder was fired up while all of this was going on it may have tripped the 200 amp main.
I do agree that it will be rare to ever need more than 200 amps at one time and I still may go with the smaller service. Home Depot and Lowes sells the 400 amp stuff and the cost of the larger equipment that I would have to buy isn’t really that much more money as long as there is no added monthly bill which I still need to check on. I’m big into metal fabrication, welding, and I have a medium sized machine shop with motor starting loads but what about the future? With 150 acres I may decide to farm, start a winery, build a rock crusher,:crazy saw mill, or just sell the place and the larger service might be a good selling point. The larger hydro company wire is free on the initial install but if I wanted to upgrade in the future they would charge to run it.
I wasn’t planning on researching this install for a few years but if I want to change my conduit route and go with one transformer I need to get this done now. Here are some examples I have found on the web and I would appreciate some input if you or anyone else viewing is familiar with this equipment. Ijoker?
Here is a 400 amp meter socket, nothing special but really really big. Notice how there are two separate 200 amp services coming out of it.
Here is an example from a different hydro company of a 400 amp service split down to 200 amp disconnects which is what I want to do.
These meter mains are really cool, a 400 amp meter socket and a breaker panel all in one enclosure. The second 200 amp breaker would fill the open area on the far right. What is nice about this setup is I would have easy access to some smaller clip-in breakers. I’m pretty sure that my well pump is going to be close by and that would be a perfect application. The generator shed could use a light and some outlets so there is another breaker spot taken up. All of this equipment is rated for outdoor use but I would feel better having at least a roof over it because I have seen how corroded and rusted this stuff can get over the years.