Timeline for What is the correct wiring (including Ground) for two main load centers plus transfer switch?
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| Oct 19, 2020 at 18:31 | vote | accept | Vette | ||
| Oct 19, 2020 at 18:30 | history | edited | Vette | CC BY-SA 4.0 |
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| Oct 16, 2020 at 2:48 | answer | added | ThreePhaseEel | timeline score: 3 | |
| Oct 15, 2020 at 23:53 | comment | added | ThreePhaseEel | @Vette -- unless you are putting at least one of the tankless heaters on the standby panel, your load on the non-standby panel for NEC purposes won't be <=200A, (in fact, it may not even be <= 225A...) | |
| Oct 15, 2020 at 22:49 | comment | added | Vette | @ThreePhaseEel. Yes forced air (2 units) and 3 electric tankless water heaters are set in stone. Based on expected usage, peak actual load on each panel should be <=200A. Is the neutral and ground wiring in the above diagram up to code? | |
| Oct 13, 2020 at 0:59 | comment | added | ThreePhaseEel | @Vette -- I'm asking because I see other issues with your setup (like an overloaded panel!), and might be able to get you going down a better path (and perhaps a less costly one even!) with better knowledge of your requirements. Does the house have gas service (for furnace/range), and is the notion of forced-air heating something that's set in stone for you? | |
| Oct 12, 2020 at 14:03 | comment | added | Vette | @ThreePhaseEel Using tankless at each bathroom for instant hot water that never runs out. New house. But the big question: Is the wiring setup in the diagram up to code? I just want to make sure I'm running ground and neutral in a legal way. | |
| Oct 10, 2020 at 2:41 | comment | added | ThreePhaseEel | @Vette -- why tankless water heating, first off? Also, is this a new build or an upgrade of an existing house? And we need the square footage to compute the general lighting load as per NEC article 220... | |
| Oct 9, 2020 at 12:51 | comment | added | Vette | Utility: Udwi REMC, and they confirmed they can do 400A to my location. Loads include 3 point of service tankless water heaters (112A, 75A, 30A), two A/C (40A each), Lift (30A), Elec Dryer (30A) and 36 various single-pole circuits. And per what I've read yes you can connect two 200A panels to a 400A meter as long as the panels are next to each other. I just want to make sure I do the wiring in a way that is up to code. | |
| Oct 9, 2020 at 11:09 | comment | added | Jasen | can you even connect a 200A panel directly to a 400A meter? | |
| Oct 9, 2020 at 1:34 | comment | added | ThreePhaseEel | @Vette -- who do you have for an electric utility? Also, how many square feet is this house, what are you putting in for HVAC, and are your other "big 3" loads (water heater, range, clothes dryer) gas or electric? Finally: what is your rationale for a Class 320 (400A) service? Unless you have some significant ADU or outbuilding/shop shenanigans or a seriously mansion-sized house, services that large are basically never called for anything that's a single-family dwelling at its base... | |
| Oct 9, 2020 at 1:31 | comment | added | ThreePhaseEel | @Harper-ReinstateMonica -- sidenote: there's a case for PVC from meter pan to main panel(s) due to the potential for unwanted neutral currents through metal conduit between those two parts (since meter pans are bonded to neutral). In my book, it's yet another reason to use an integral meter-main... | |
| Oct 8, 2020 at 19:17 | comment | added | Vette | Using Schedule 40 PVC Conduit b/c metal is much more expensive and annoying to deal with. Much cheaper to simply run copper wire for ground, but want to make sure I wire it correctly. And if ground and neutral are bonded in the service panels, I can just run the copper to neutral bus. Is that against code? (There are no inspections in this locale of any type but want to stay up to code if possible anyway.) | |
| Oct 8, 2020 at 17:56 | comment | added | Harper - Reinstate Monica | And you're not obliged to put grounds on the neutral bar in a main panel. You can put them on a separate ground bar if you like. I would do that in panel B just because it's cheap/easy and will CYA if the AHJ decides to view the ATS as the main panel or if you get pinched by outside-disconnect requirements. I would also do it in panel A because why not. | |
| Oct 8, 2020 at 17:53 | comment | added | Harper - Reinstate Monica | You should be using metal conduit (EMT or Rigid) to connect meter pan, service panels and transfer switch. That will take care of grounds amongst all those boxes. This is no trivial matter since some of these boxes may not have provisions for ground lugs. | |
| Oct 8, 2020 at 17:29 | comment | added | Ecnerwal | while a metal water pipe (if you are so archaric as to have one of those) should be tied into (bonded to) the grounding system that alone is not a grounding system. If you are having concrete foundations poured in direct contact with soil, a Ufer ground a.k.a. concrete encased electrode is as easy as a 4AWG copper wire and a suitable clamp connected to the rebar in the foundation. | |
| Oct 8, 2020 at 17:00 | history | asked | Vette | CC BY-SA 4.0 |