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Discussion Starter #1
Hello...

I currently have 200amp service with a 200amp main/meter combo, and a 100amp subpanel coming off the main above with a 100amp breaker.

I want to install an Electric whole house tankless hot water heater. I am not a big fan of propane.

My power company inspector suggested this to me. For $300 they can setup a meter socket on their power pole, and run a 400 amp service from it. This would mean I only pay for one meter. I didn't ask him this question so I am going to ask it here.

I planned on running an additional 200 amp service to my storage building. From there I would go underground over to my house to run the tankless water heater. But then I was wondering if I had to put the second service on the storage building. Why can't I just put it on my house?

Can I have Two 200 amp Mains on the outside of my house in close proximity. Both would have individual lines coming from the power company's pole which will be ran out of their meter socket which will also be on the power company's pole. Both services would be grounded to the same grounding rods.
 

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Electrician
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I'm not sure what the NEC says, but the Canadian code (that I am familiar with) states that you can only have 1 service per structure (I'm summarizing here). What you're planning i would consider as 2 services (regardless that they're on 1 meter), as there would be 2 aerial drops rather than 1.

If you'd like everything connected to the house then feed everything from the house, I'd have 400 amp rated gear installed on the house, and split that 400 amps up, 200 for the house and 200 for your outbuilding.

What the POCO guy was suggesting was probably central metering.

This is all I can offer. Others that are more knowledgeable with the NEC will tell me if I'm wrong shortly haha
 

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Well sure you can have 2 x 200 AMP services ran to the same building but just how much is running off your current 200 AMP?

Have you thought about 3 Phase? It could save you money and the load balance is much better.


Cheers!

TRI0N
 

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Have you thought about 3 Phase? It could save you money and the load balance is much better.


Cheers!

TRI0N
If the POCO charges commercial rates for 3 phase, it will most definitely NOT be cheaper than single phase 400 amp service.

POCO might not even have 3 phase in the area, now you'd be talking tens of thousands of dollars to have 3 phase installed.
 

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If the POCO charges commercial rates for 3 phase, it will most definitely NOT be cheaper than single phase 400 amp service.

POCO might not even have 3 phase in the area, now you'd be talking tens of thousands of dollars to have 3 phase installed.
This is in the US. Here in California I have 3 building that were all single phase however the between the 3 buildings it was being fed only 300 AMP and in order to bump that to 600 AMP the new line must be ran underground because they won't do new cable runs above ground anymore. There was no price difference for installing 3 Phase by SCE. Not sure what they charge in Missouri but he should at least look into it.


Cheers!

TRI0N :vs_cool:
 

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Discussion Starter #6
300 amp minimum total service to the residence, or an upgrade to this level, is necessary to install a Tempra 36 Plus as it has a maximum power draw of 150 amps and requires 3 separate 50 amp breakers with 3 separate runs of 6-gauge copper wiring.

200 amp service won't work. 400 would be fine. The house is all electric no gas.

I don't understand 3 phase so I would not be able to do much with that.

If I can run 2 mains on the house that would be easiest. It would only be 10-20 feet of wiring to the inside closet where the tankless would be located, and I could go with a cheaper 8 space main outdoor panel.

I didn't want to go 400 amps on the house. The price of the meter socket, and wiring plus putting that heavy beast inside pvc, and then on the house was just more than I wanted to do.

Yes I guess the inspector was talking about central metering. He just said I would not have to pay for 2 separate meters, and it could be 400 amps if I wanted it to be. He mentioned they would cover up the meter socket I currently have but did not say how.
 

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3 separate breakers on a single phase for 240 Volt Water Heater? Is that a typo?

No typo. It's common practice for tankless water heaters. Heating water instantly as it flows through the water heater takes a huge amount of power. Which is why the advice is usually to go with natural gas or propane if at all possible.


Three phase power just isn't available in most residential neighborhoods.
 

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Yes I guess the inspector was talking about central metering. He just said I would not have to pay for 2 separate meters, and it could be 400 amps if I wanted it to be. He mentioned they would cover up the meter socket I currently have but did not say how.
This would definitely be central metering. A set of CT's go on the hydro pole on the secondaries that feed your property and connect to a meter installed on the pole. They'll likely then install jumpers in the meterbase, and install a blank cover on the opening.

I'm not sure how much work the POCO will actually do, as in my area, we have to do all this work, except for supplying a few items and final connections to power.

As far as your options, I cannot comment much. For central metering, a meterbase is not needed on the house, which means you could install a 400 amp service entrance rated disconnect switch, out of that to a splitter, from the splitter to the existing 200 amp panel (some rework of the grounding and bonding is needed), and from the splitter to a fusible disconnect for the instant water heater. You could also install a fusible disconnect switch and feed the out building, or have a second aerial drop installed to that outbuilding.

But I'm not familiar with the NEC, so this is only doable If the NEC allows this (my Canadian code does, I don’t see why the NEC wouldn't...).
 

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Generally, two services are not allowed on one structure. Special conditions, such as firewalls,etc., may allow for more than one service.
 

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Discussion Starter #12
This would definitely be central metering. A set of CT's go on the hydro pole on the secondaries that feed your property and connect to a meter installed on the pole. They'll likely then install jumpers in the meterbase, and install a blank cover on the opening.

I'm not sure how much work the POCO will actually do, as in my area, we have to do all this work, except for supplying a few items and final connections to power.

As far as your options, I cannot comment much. For central metering, a meterbase is not needed on the house, which means you could install a 400 amp service entrance rated disconnect switch, out of that to a splitter, from the splitter to the existing 200 amp panel (some rework of the grounding and bonding is needed), and from the splitter to a fusible disconnect for the instant water heater. You could also install a fusible disconnect switch and feed the out building, or have a second aerial drop installed to that outbuilding.

But I'm not familiar with the NEC, so this is only doable If the NEC allows this (my Canadian code does, I don’t see why the NEC wouldn't...).
Thanks for this I would not have considered a 400 amp disconnect.

I bought a second Main Panel 200 amp eaton 30 spaces 60 circuits some wiring, metal conduit, weatherhead, etc.

I have some people out here removing trees for me so I asked them to trench a line with their backhoe going from my little shed over to the house in case I need to use that structure for the second panel. It will just be a lot more work going that route since I will have to run an extra 75 feet of thhn cable x 3 and a ground plus put it all in conduit.

It would be much better if I could leave this second panel mounted to the back of the house which is where I have it now. It is just screwed to the exterior nothing is hooked up yet. Maybe they will OK it since I am going to have a central meter.

I have been trying to get ahold of the inspector with no luck. My power company shut down the office due to covid and just reopened friday so I can't ask any questions at this point.

I can ask questions here though.

If I am allowed to have the 2 services for 1 structure coming off of the 1 400 amp central meter...

My reading tells me that I need to ground both to the same grounding rod?
I cannot have them on separate grounding rods?

Can I still put a grounding rod close by the second service and ground all of it together?

If I have to put 1 service on my little shed which is not attached to my house it does not need to be grounded to the same grounding rod as the other service?
 

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Two distribution panels coming off of one meter is NOT two services, it is ONE service.
 

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Hi, just curious as to what the pay back will be for changing this to the electric tankless?
Geo
 

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300 amp minimum total service to the residence, or an upgrade to this level, is necessary to install a Tempra 36 Plus as it has a maximum power draw of 150 amps and requires 3 separate 50 amp breakers with 3 separate runs of 6-gauge copper wiring.

200 amp service won't work. 400 would be fine. The house is all electric no gas.
OK, all electric house, my friend has the same situation except in the snowbelt. All electric neighborhood, heat pump, 150A of emergency heat, so 400A service.

In America, the usual way 400A service is done, to make it affordable, is to have the meter feed two 200A main panels side-by-side.

Seriously. I know a lot of people do a double-take when they hear this, and I regularly have novices disbelieving me. But that's how it is.

Two $130 main panels side by side, plus a $250-ish meter pan. The meter pan is even designed to be used only this way: It has dual lugs that can only take 4/0 wire (for 200A): it is incapable of taking 500 kcmil (for 400A) and is not rated for paralleling.

In fact, the popular Siemens 400A meter-main simply does that in a single enclosure: it has a 200A "main breaker" feeding a 4-8 space micro-panel then feed-thru lugs. Then there's space for a second, optional 100-200A main breaker (which is hardly optional; you need it to get more than 200A out of that panel lol; it just isn't included.)

Really, that setup is intended for a "farm pole" where the service point is a pole, and power scatters in 6 directions to house (200A breaker), barn (feedthru lugs), pumphouse, pool, chicken coop etc. (all breakers in the micro-panel). But it would also work in NEC 2020 territory where disconnects must be outdoors: it feeds 2 panels in the house: one off the straight 200A breaker and the other off the feed-through lugs.


I don't understand 3 phase so I would not be able to do much with that.
Waste of your time. North American 3-phase is mostly 480V wye (277V per leg) which won't play with any consumer heater that I've found. They do have 240V "Wild-leg" delta, which is just common split-phase with a "wild" third phase supplied, with 240V pole-pole: that would work, but why fool with it?

But yes, that is why larger tankless heaters all have three elements. Because in the other 5 continents, you have 230V/400V 3-phase "wye" running right up to your house, you normally are given 1 phase but you can request all 3. Those tankless heaters are in pig's heaven on that! And you can wire it as a 4-wire MWBC (L L L N) instead of 6 wires (LL LL LL) as you must here. (240V wild-leg could do it with 3 conductors, but they'd be larger.)


If I can run 2 mains on the house that would be easiest. It would only be 10-20 feet of wiring to the inside closet where the tankless would be located, and I could go with a cheaper 8 space main outdoor panel.
Don't start me on cheaping out and shorting yourself on breaker spaces lol. But in this case, yeah, that makes sense. For instance that Siemens meter-main would be a good fit for that job, since you could use 6 of the 8 "micro-panel" spaces for the heater, and since you can only provision 50A more on that 200A half of the panel, just use one more 50A breaker and don't use the subfeed lugs. (because if you did, you'd need 200A -rated wire). Then power the house off the second main breaker. (which you could size 200A or 100A to suit).

I didn't want to go 400 amps on the house. The price of the meter socket, and wiring plus putting that heavy beast inside pvc, and then on the house was just more than I wanted to do.
Yeah, following the bog-standard "split into two 200A sub-services" concept, you'd run that as dual 4/0 runs in dual conduits. NOT a 500 kcmil monster.
 

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So the two panels need to have the grounds tied together?
Yeah, and this will happen by default if you use metal conduit to connect the panels. Don't even have to think about it.

In fact, put a few EMT conduit cross-connects between the two panels. They have all sorts of uses for passing through wires, but yeah, they also connect the grounds for you.
 

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Discussion Starter #18
The two panels are about 60 feet apart.

One is on the back of the house the other on the side.

Each panel will have a feed coming from the power company's pole/central meter. The power company will run the line drop to each panel.

Each panel will have an OVERHEAD feed. One panel is in pvc conduit not going through the roof. This panel has been approved passed inspection and is live at the moment. It is also a meter/main combo.

The other panel will go through the roof which is in metal conduit, and is only a panel no meter socket.

What is bugging me is this;

Since these panels will not be grounded to the central meter. I am assuming the power company will not run a separate ground in their overhead feed, but I could be mistaken perhaps they will.

Why does each panel need to be grounded to each other?

I don't mind grounding them to each other. It is not that hard to run a ground that far. I just don't understand why they need to be, but I am still a novice at best with this stuff.
 

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Ah OK, I was stuck on 2 panels adjacent. My bad.

The grounding point with your neutral-ground bond is supposed to be your "main panel", which is the first disconnect after the meter. Yeah, on a "farm pole" that means it's out standing in its field. Beyond this point, all wires are feeders, and they must be 4-wire with separate neutral and ground.

Further, any building other than the service building needs its own ground rod(s). The ground rods deal with natural electricity, the ground wires deal with fault current. Need em both.

The 2 panels don't need to be grounded to *each other* (my bad), but they both need to be tied into the building's Grounding Electrode System (i.e. the ground rods) - this will have the effect of grounding them to each other. Grounding and bonding are not the same thing, but they interact. It's a deep subject to say the least.



You said you'll have an overhead pole line carrying your feeder from the main panel to the two subs that are 60' apart at the house. That is fine, NEC has rules to cover that.

The snag is that if you hire the power company to do this, they will want to run a 3-wire drop because NESC says that's good enough for a *service*. They follow NESC all day and don't know anything about NEC. So you must be forceful that they run a 4-wire feeder (3 insulated conductors + 1 bare). They have it on the truck for 3-phase services.
 

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Don’t know your situation but around here, everything past the meter is the owner’s responsibility, including the installation from the meter to the structure. Perhaps your POCO is different.
 
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