MEP 805B wired to split 400amp panels

[Guyfang]

6 inchs of snow this morning! Cold?

 

[Evvy Fesler]

Couple questions if I can. Will the transformer be inside? Most Of the transformers I am seeing are 480v by 208 v but that is different than what you are using correct?

Yes, it's different because that transformer would step down the input voltage by about half.

 

[Evvy Fesler]

6 inchs of snow this morning! Cold?

If we got 6-inches of snow we'd be shut down for a couple of weeks while the solar plows cleared the roads!

 

[Evvy Fesler]

I'm putting the transformer outside, which will make my install simpler for several reasons, but also largely because I have no easy way to get the 500lbs transformer into the basement. I need to make rain hoods for it so it will be nema 3r.

I was looking for a 30kva delta-wye 208/120, but I couldn't find any locally, I was able to find a 63kva delta-wye 460/266. As the winding ratios are the same it will largely work the same at 208v as the nameplate 460. A 480/208 has different winding ratios, so if you run the primary delta at 208 your neutral will be low, more like 90v rather than 120v.

Also keep in mind that on the higher voltage units the rated current will be less that a similar rated 208v unit as the higher voltage (that you're not using) eats up the kva raining. Even though my unit is rated at 63kva it's only good for 79A/leg. This is still plenty for a MEP-804B, but probably less that one would expect for 63kva.

You may be pleasantly surprised by cost of freight. Calling or using freight direct websites will get the best rates. Avoid the brokers. I shipped a main generator (600-lbs) from Las Vegas to home in NC for $175 via YRC. It came in promptly. They transferred it to the bed of our pickup truck via their liftgate. We put it on the ground with a portable engine hoist. We went to South Carolina, just over the border to get the transformer, and did the same thing except they put it onto the pickup with a forklift. A half dozen 2' lengths of 3/4" steel conduit (hanging around in the barn) made rolling the transformer into place a breeze. Just giving y'all ideas... gawd knows I need ideas!

 

[Evvy Fesler]

I don't have 3 phase 400A, but I do have 2 phase 400A with both a 400A disconnect as well as a 400A transfer switch.

Here's how I wired mine:

View attachment 886030

500 MCM Al coming up into the meter base on far left. From there's its all 300 MCM Cu, except ground which is 1/0 Al.

Here it is with all the covers in place:

View attachment 886031

Here's a very simplified diagram of the layout:

View attachment 886032

House has 2 200A sub-panels and the shop has a single 200A sub-panel as well as a 225A solar sub-panel (I have 60 kW worth of solar arrays).

I actually have 2 generators, a MEP 803A and a Kubota 20 kW. I can switch between them with a manual 100A transfer switch.

The only place in the whole system where Neutral and GND are bonded is in the 400A disconnect switch:

View attachment 886033

Did all the work myself and had the county come out and inspect. Dual ground rods and the shop and the house. 200' run between the shop and the house, using 3x 500 MCM Al with 1/0 GND.

POCO made me put in 3" conduit for the run from the pole to the meter base. They didn't require that when I did this 20 years ago, but this year they did.

View attachment 886038

Got a 50 KVA transformer on the pole going up to 14.4kV. Main reason for the 50 KVA transformer is not so much what I consume, but being able to handle me pushing 60 kW into the grid during the summer months.

"...being able to handle me pushing 60 kW into the grid during the summer months."

Whaaaat?