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Old 08-08-2015, 12:23 PM   #1
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Third service panel - ideas needed...


Hey all,

Looking for creative ideas / experienced ideas here... my home has 320/400A service fed by 350 kcmil conductors from a 37.5 kVA dedicated transformer, with dual lugs at the bottom of the meter. Lug set 1 runs to my 200A automatic transfer switch, which then feeds a CH 200A panel (#1) in my home, covering most of the loads in the home. Lug set 2 runs directly to a second CH 200A panel, which feeds the loads that do not need to be backed up - a 100A sub in my machine shed, a 60A sub for hot tub, a 70A sub for pool equipment and bathroom, and a 100A sub in the garage for electric car charging (charges at 80A, but continuous load rules require 100A).

I'm preparing for a second EV that is expected to charge at the same rate (80A), and both EV's may charge at the same time. From a load calculation standpoint, both of them charging would require 100A each (continuous load rules), which won't work in my existing panels. I'm looking to adjust my infrastructure so that can happen. It doesn't appear that the meter base (supplied by the co-op) can be adapted for a third set of lugs, and as I need more than 100A, so the tap connectors I've seen available can't be used. PoCo says based on their monitoring I have plenty of room on the service for it, and that I won't need to perform a service upgrade - good because 350-compact is all they can squeeze through the existing service conduit.

I was thinking that I could use a 400A terminal box, use a single set of conductors between the meter and terminal box, then take individual conductor sets to the ATS, panel #2, and add a new 200A disconnect in the basement, that then feeds a 200A sub in the garage for the two chargers and backup 50A RV receptacle.

Any suggestions? All subject to PoCo agreement, of course, but they're willing to work with me, compared to my other experience with the big boys.

EDIT: I'm also trying to avoid a new meter because the meter charge is $40/month for a service based on how they've structured fixed cost vs. usage.

(I can configure the EV's to use delayed charging, so that they wouldn't charge at the same time -- however, occasionally we have other EV drivers visit who will want to charge as well and I'm leaving options open. This is my fallback plan.)

Last edited by flasherz; 08-08-2015 at 12:39 PM.
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Old 08-08-2015, 01:34 PM   #2
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Quote:
Originally Posted by flasherz View Post
Hey all,

Looking for creative ideas / experienced ideas here... my home has 320/400A service fed by 350 kcmil conductors from a 37.5 kVA dedicated transformer, with dual lugs at the bottom of the meter. Lug set 1 runs to my 200A automatic transfer switch, which then feeds a CH 200A panel (#1) in my home, covering most of the loads in the home. Lug set 2 runs directly to a second CH 200A panel, which feeds the loads that do not need to be backed up - a 100A sub in my machine shed, a 60A sub for hot tub, a 70A sub for pool equipment and bathroom, and a 100A sub in the garage for electric car charging (charges at 80A, but continuous load rules require 100A).

I'm preparing for a second EV that is expected to charge at the same rate (80A), and both EV's may charge at the same time. From a load calculation standpoint, both of them charging would require 100A each (continuous load rules), which won't work in my existing panels. I'm looking to adjust my infrastructure so that can happen. It doesn't appear that the meter base (supplied by the co-op) can be adapted for a third set of lugs, and as I need more than 100A, so the tap connectors I've seen available can't be used. PoCo says based on their monitoring I have plenty of room on the service for it, and that I won't need to perform a service upgrade - good because 350-compact is all they can squeeze through the existing service conduit.

I was thinking that I could use a 400A terminal box, use a single set of conductors between the meter and terminal box, then take individual conductor sets to the ATS, panel #2, and add a new 200A disconnect in the basement, that then feeds a 200A sub in the garage for the two chargers and backup 50A RV receptacle.

Any suggestions? All subject to PoCo agreement, of course, but they're willing to work with me, compared to my other experience with the big boys.

EDIT: I'm also trying to avoid a new meter because the meter charge is $40/month for a service based on how they've structured fixed cost vs. usage.

(I can configure the EV's to use delayed charging, so that they wouldn't charge at the same time -- however, occasionally we have other EV drivers visit who will want to charge as well and I'm leaving options open. This is my fallback plan.)

I think that I would pull the line for the second electric vehicle from the generator panel. That way you will have at least one charger available during an extended outage.
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Old 08-08-2015, 01:43 PM   #3
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Take out your "lug set" that gives you two outs on each leg and add a "lug set"
that gives you three or four out..

feed existing as you have, feed a new 100 amp disconnect for your new load.

I agree would be nice to have a charger off the generator, but not sure if it will handle it.

If so, "lug set" (ha ha) from the transfer switch, or ad a sub panel from the generator panel.

If getting one or two hole three barrel (or four barrel) lugs are tough to fit in the meter pan, you could install a larger lug with a larger barrel, install large wire and tap off that in a trough..
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Old 08-08-2015, 02:50 PM   #4
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Stop buying electric vehicles.
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Old 08-08-2015, 03:38 PM   #5
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you have a problem since you can only have one set of service conductors from a single service other than where the exceptions apply:

Quote:
Part IV. Service-Entrance Conductors

230.40 Number of Service-Entrance Conductor Sets. Each service drop or lateral must supply only one set of service-entrance conductors.

Exception No. 1: Buildings with more than one occupancy can have one set of service-entrance conductors for each service of different characteristics [230.2(D)] run to each occupancy.

Exception No. 2: One set of service-entrance conductors can supply two to six service disconnecting means as permitted in 230.71(A).

Exception No. 3: A single-family dwelling unit with a separate structure can have one set of service- entrance conductors run to each structure from a single service drop or lateral.
then you have to have a disconnect for that SINGLE set of service conductors that enter any given building as close as possible to the point of entry to the building. That removes the possibility of what you want to do.

if your garage is attached to the house, you have already gone beyond what the code allows. I also have other concerns that there are loads from each panel in any one building which is a code violation as well.
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Old 08-08-2015, 04:36 PM   #6
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I think that I would pull the line for the second electric vehicle from the generator panel. That way you will have at least one charger available during an extended outage.
Definitely a possibility, but could cause a generator problem, as genset is 25 kW. If we have a power failure and a car is charging during summer, it plus the AC and other refrigeration loads could cause the generator OCPD to trip.

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Originally Posted by InPhase277 View Post
Stop buying electric vehicles.
Not going to happen... at 3 cents per mile vs. 20-30 in any other vehicle, it's economical - and that's grid price. I have an 18 kW solar plant that produces about half the power I use yearly, so after the payback period my transportation is free.

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Originally Posted by nap View Post
then you have to have a disconnect for that SINGLE set of service conductors that enter any given building as close as possible to the point of entry to the building. That removes the possibility of what you want to do.

if your garage is attached to the house, you have already gone beyond what the code allows. I also have other concerns that there are loads from each panel in any one building which is a code violation as well.
See exception #2 to 230.40, right above the part you bolded. It's very common for 400A service to use dual lugs at the base of the meter to serve two 200A service panels inside the home when the panels are co-located. The current attached garage panel is a subpanel off service panel #2 (grid-only). Exception 2 permits up to 6 disconnecting means in separate enclosures onto a single service drop. I'm looking to expand from 2 to 3. There would be a 200A service disconnect in the basement with the other two panels that then fed a 200A sub in the garage.

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Originally Posted by ritelec View Post
Take out your "lug set" that gives you two outs on each leg and add a "lug set"
that gives you three or four out..
I've been digging through the various catalogs that I've been aware of, but haven't been able to find a set that gives three or four out on a 3/8" stud... are they easily found?

Last edited by flasherz; 08-08-2015 at 04:41 PM.
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Old 08-08-2015, 04:39 PM   #7
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feed existing as you have, feed a new 100 amp disconnect for your new load.
I hadn't thought of that, I could use the 100A tap piggyback connectors into one of the lugs. Might be trouble to get another conduit out to the garage for the other one, but it might be possible. I'll consider this too.
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Old 08-08-2015, 04:41 PM   #8
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See exception #2 to 230.40. It's very common for 400A service to use dual lugs at the base of the meter to serve two 200A service panels inside the home. Exception 2 permits up to 6 disconnecting means in separate enclosures onto a single service drop. I'm looking to expand from 2 to 3. There would be a 200A service disconnect in the basement with the other two panels that then fed a 200A sub in the garage.
This can be done IF ALL the disconnects are located immediately adjacent to each other. Are they or will they even after the new one? If not, it is not legal.

if the install is otherwise legal, the lugs you are looking for (from what you have described anyway) are commonly available.

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Old 08-08-2015, 05:05 PM   #9
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I just want to extend my apologies here. Either I misread the original post, put something in there myself that was not presented or something was changed but for the life of me the way I originally read it does not seem the same as I read it now.


so, hopefully to onto a better foot with ya:


are and will all main discos in any one building be within reach of each other when are standing at any other disco in that building?
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Old 08-08-2015, 06:49 PM   #10
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I just want to extend my apologies here. Either I misread the original post, put something in there myself that was not presented or something was changed but for the life of me the way I originally read it does not seem the same as I read it now.


so, hopefully to onto a better foot with ya:


are and will all main discos in any one building be within reach of each other when are standing at any other disco in that building?
No worries. It's already a complicated enough situation to try and get into a post. The answer to the question is yes - the third disconnect will be co-located with the transfer switch (service disconnect #1) and grid-only panel #2 (service disconnect #2) before feeding a 200A panel in the garage.
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Old 08-08-2015, 08:14 PM   #11
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it really isn't that complicated. The job I am on now, which is only an addition, has 12 panels on one floor and, I believe, 15 on the floor below that (I would have to take another look since I am not working much on that floor). Then on the floor below that there are another group of several larger distribution panels, a half dozen more branch circuit panels, and some switch gear plus 2 or 3 transfer switches and a high voltage disconnect.

then toss in a half dozen or so transformers and you have most of the major parts.

and that is not a really large install in the bigger picture of things. It is only a 3 story addition (on top of an existing 2 story construct) on part of a small hospital.

so, what kind of lugs are you needing? I have dealt with a few different 320 meters that would not all accept the same lugs., You might try looking for a 3 or 4 port (whatever you need) stacked lug.

maybe something like this:



if that is not available your idea of the junction box with a tapped conductor would (or should be although I had an argument with one inspector over this) be legal. There are myriad ways to put together that bit of the system.
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Old 08-08-2015, 10:16 PM   #12
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so, what kind of lugs are you needing? I have dealt with a few different 320 meters that would not all accept the same lugs., You might try looking for a 3 or 4 port (whatever you need) stacked lug.
Wow... I can't believe I didn't find those anywhere, guess I was trying to overcomplicate my searches. That seems to be exactly what we need, NSI 600T-4 or similar.
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Old 08-08-2015, 11:24 PM   #13
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Wow... I can't believe I didn't find those anywhere, guess I was trying to overcomplicate my searches. That seems to be exactly what we need, NSI 600T-4 or similar.
Hey, it's what I do for a living. I need to know about things like this
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