# Questions on 320A resi service



## Almost Retired (Sep 14, 2021)

look into XHHW alu singles rather than triplex
smaller pipe than triplex
same ratings as THHN, pulls easy just like it too
you may be able to parallel in one pipe instead of 2
should be cheaper that way


----------



## Tonedeaf (Nov 26, 2012)

JollyElectrode said:


> Howdy all,
> 
> I need to do my first 320A panel, we are now on NEC2020. It looks like the new Siemens panels with the dual 200A disconnects will be perfect, specifically looking at the MK0402L1400SC.
> 
> ...


I did three 320 amp meter socket this yeah.....one for PPL and two for PECO.

I also used Siemens, you have to buy the breakers that fit the socket....I think I paid like $220 each for the 200 amp breakers

They utility used 500 MCM AL direct burial for service side. all three were underground direct burial. I had to excavate, provide screening and back fill.....they laid the cable in my trench.

I used aluminum 250-250-250 MC cable for the 200 amp panels because they are sub panels not service panels. Each time when I priced it, 250-250-250 MC cable was cheaper by $3/foot than SER cable

I used # 2awg solid copper for ground at the combination meter to two rods. Check the tables I think 3 awg solid it good, my supplier doesn't sell it.

I terminated the socket for the PECO guys....it was a sub contractor and they only sent two guys out and they had to change the transformer pedestal.


----------



## SWDweller (Dec 9, 2020)

The questions your asking indicate to me your not an electrician. 
The place you need to be asking the questions is the POCO and the AHJ.
I bet you do not even know the AIC's where your going to install this service.


----------



## JollyElectrode (3 mo ago)

SWDweller said:


> The questions your asking indicate to me your not an electrician.
> The place you need to be asking the questions is the POCO and the AHJ.
> I bet you do not even know the AIC's where your going to install this service.


You would be quite wrong. I see questions a from electricians that are a lot dumber and simpler than this regularly asked on this forum.

Since you didn't answer the questions, I assume you don't know the answers yourself. The NEC 2020 changes were quite significant and 320A residential services are quite new. I see lots of similar questions asked here and elsewhere, generally without conclusive answers, so it would seem that I'm not alone.

Since you can't answer the questions either, does that mean you're not an electrician?


----------



## kb1jb1 (Nov 11, 2017)

Tonedeaf said:


> I did three 320 amp meter socket this yeah.....one for PPL and two for PECO.
> 
> I also used Siemens, you have to buy the breakers that fit the socket....I think I paid like $220 each for the 200 amp breakers
> 
> ...


No expansion fitting as it comes out of the ground? We don't use them either even though we are supposed to.


----------



## JollyElectrode (3 mo ago)

Tonedeaf said:


> I did three 320 amp meter socket this yeah.....one for PPL and two for PECO.
> 
> I also used Siemens, you have to buy the breakers that fit the socket....I think I paid like $220 each for the 200 amp breakers
> 
> ...


Thanks for your response. Do you happen to have a picture with the right side open as well? So you only ran 3 wire(no ground) from your meter/main disconnect to your inside panels? 

Doesn't the external disconnect make every panel after that a sub-panel and require a 4 wire connection?


----------



## kb1jb1 (Nov 11, 2017)

JollyElectrode said:


> You would be quite wrong. I see questions a from electricians that are a lot dumber and simpler than this regularly asked on this forum.
> 
> Since you didn't answer the questions, I assume you don't know the answers yourself. The NEC 2020 changes were quite significant and 320A residential services are quite new. I see lots of similar questions asked here and elsewhere, generally without conclusive answers, so it would seem that I'm not alone.
> 
> Since you can't answer the questions either, does that mean you're not an electrician?


This forum is nation wide so what equipment in one area might not be allowed in other areas. Or some could be unfamiliar with the different equipment or methods. First, here we would not be able to use that equipment, it is not utility company approved. Second we would have to bring all grounding electrode conductors into the double 200 amp disconnect and then 4 wire to the interior panels. Is there a common buss bar with enough ports and a main bonding jumper in the double 200 amp disconnect?


----------



## Ostrich Society (Dec 14, 2021)

Where I live, the POCO runs service laterals for residential services 320 and under. Often times they just run single 250 AL give or take depending on where the transformer is. They have their own rules on how they size their wire.

If your worried about the equipment ground lugs being too small just buy some crimp on ilsco reducing pins/lugs.

Where I live that service would be considered the service point and you would be required to run 4 wire feeders from there to the interior panels. I would also be required to size feeders off 310.16 not 310.12 seeing as how the feeders do not carry the entire load for the house.


----------



## SWDweller (Dec 9, 2020)

Maybe 320's are new where you are. Where I live they have been around for at least 10 years and maybe longer. We have other MFG's that make equipment for this purpose for a lot less money than purchasing from the big MFG's. I personally never saw the sense in 320 when I can put up a full 400 for less money, using the local MFG equipment. 
I did not answer your questions because my answer may be different that what you need. I specifically stay away from Siemens equipment. In 50 years never installed a new Siemens anything and I am not going to start now. Like all products some are strong in area A and some are stronger in area B. I do not have an account at wholesaler that sells Siemens. 

I elected not to answer your equipment specific questions because I have no knowledge of Siemens.
Where I live if you want to run 200 amps your using 250 mcm AL or 4/0 copper. Which is a worthless point to you because where I live we have temperature derates that must be considered. I have no idea if your area is the same.
The meter socket on the equipment you provided is not even allowed here. The POCO's I have do not accept lever operated meter sockets. 
I did ask a question which you did not answer about the AIC's. Is this piece of equipment on your POCO's accepted equipment list? Would not pass my POCO. The model numbers of branch breakers have different listings to meet different requirements. None of those questions will probably be answered here.


----------



## JollyElectrode (3 mo ago)

kb1jb1 said:


> This forum is nation wide so what equipment in one area might not be allowed in other areas. Or some could be unfamiliar with the different equipment or methods. First, here we would not be able to use that equipment, it is not utility company approved. Second we would have to bring all grounding electrode conductors into the double 200 amp disconnect and then 4 wire to the interior panels. Is there a common buss bar with enough ports and a main bonding jumper in the double 200 amp disconnect?


Yup, I understand that. Apparently that other person doesn't given his/her rude response. I've learned not to judge people, or step on other's toes. We all know things others don't. If you can't be helpful to someone, just move on. I have to teach my children that every day, it's a hard thing for some to learn I guess.

Here, the utility company doesn't provide any approvals or any disapprovals for that matter. I kind of scratch my head at that, but oh well. I know some are extremely strict, even providing the meter cans. There's good and bad to both I suppose.

I agree with your last statement that 4 wires are required, which is why the small ground lug is puzzling to me. I don't have the product in hand yet. It's on order. The product is so new I wasn't able to find any photos of the actual product on line, and none of the documentation mentions if there's any additional space to add ground lugs. The snippet I posted above does mention a neutral lug kit, though.


----------



## JollyElectrode (3 mo ago)

Ostrich Society said:


> Where I live, the POCO runs service laterals for residential services 320 and under. Often times they just run single 250 AL give or take depending on where the transformer is. They have their own rules on how they size their wire.
> 
> If your worried about the equipment ground lugs being too small just buy some crimp on ilsco reducing pins/lugs.
> 
> Where I live that service would be considered the service point and you would be required to run 4 wire feeders from there to the interior panels. I would also be required to size feeders off 310.16 not 310.12 seeing as how the feeders do not carry the entire load for the house.


The Utility here used to be 'full service'. They'd dig the trench, lay the wire and hook it up to the meter socket you provided. That changed sometime around 2005. Now you have to do everything up to the transfer, and leave them a couple feet. Then they wander out and drop the transfer on the ground, hook your wires and leave.

4/0 is all anyone uses for 200A service around here.


----------



## Tonedeaf (Nov 26, 2012)

kb1jb1 said:


> No expansion fitting as it comes out of the ground? We don't use them either even though we are supposed to.


I leave the straps loose so the pipe can move up and down with the ground heave.


----------



## kb1jb1 (Nov 11, 2017)

Tonedeaf said:


> I leave the straps loose so the pipe can move up and down with the ground heave.


When I first started out on my own back in the 1980s I did a 400 amp UG with 4 inch PVC. Four years later I went back and the 4 inch male adapter was pulled out of the Meter cabinet. I still don't use expansion fittings unless I think there will be a problem such as ground heaving or concrete slab poured around the pipe..


----------



## splatz (May 23, 2015)

kb1jb1 said:


> No expansion fitting as it comes out of the ground? We don't use them either even though we are supposed to.





Tonedeaf said:


> I leave the straps loose so the pipe can move up and down with the ground heave.


The NEC says


> *352.44 Expansion Fittings*
> 
> Expansion fittings for PVC conduit shall be provided to compensate for thermal expansion and contraction where the length change, in accordance with Table 352.44, is expected to be 6 mm (1/4 in.) or greater in a straight run between securely mounted items such as boxes, cabinets, elbows, or other conduit terminations.


And here's the table info from Carlon's installation guide (attached below) which tells you everything you'd want to know about expansion fittings.










You can't really go by average highs and lows, this has to work every day, even when you have record highs and lows. I figure a 110 degree temperature range would be the minimum range to cover most places in the US. 

The table says with a 110 degree temperature swing, there will be a 4.5" per 100' difference in length from coldest to hottest. Round it up to 5" even per 100' - that translates to 1/4" per 5'. So according to the rule above, you'd want an expansion fitting in any run over 5'. So if you're coming into the bottom of a box from underground, you could go up to 5' without an expansion fitting. 

Now here's a hard question. Do you have to count the vertical part of the conduit that's underground in that 5'? 

Carlon makes another product, a Slip Meter Riser, which is basiically a 2' long male adapter, a male adapter on a sleeve you can slip over conduit. It's about the same price as an expansion fitting but simpler to install for a meter riser and looks better. 











For $25 to $50 it's not nothing but it's enough to think about whether you really need it. I just removed a bunch of equipment a couple weeks ago that was installed on stubs coming up only two feet out of the ground, so no code required expansion joint, but whoever put them in put an expansion joint on every stub. I still appreciated them because it's a lot easier uninstalling and reinstalling equipment when the length of the stubs is adjustable 👍


----------



## Wardenclyffe (Jan 11, 2019)




----------



## kb1jb1 (Nov 11, 2017)

splatz said:


> The NEC says
> 
> And here's the table info from Carlon's installation guide (attached below) which tells you everything you'd want to know about expansion fittings.
> 
> ...


Here it is a utility company requirement that nobody listens to.


----------



## joe-nwt (Mar 28, 2019)

splatz said:


> Now here's a hard question. Do you have to count the vertical part of the conduit that's underground in that 5'?


Yeah, but you use a gradient which makes the calculation a little more difficult.


----------



## VitalJuice (Sep 12, 2021)

Tonedeaf said:


> I leave the straps loose so the pipe can move up and down with the ground heave.


But what if the structure doesn't? That's the problem. That's why you need the expansion joints.


----------



## VitalJuice (Sep 12, 2021)

I've worked with these panels. I was surprised to see them use CU between the meter and disconnect. Everyone else seems to be using AL these days.

I'm a little puzzled at Siemens' engineering here myself. It would seem like they intend the #2 lug to be connected to the grounding electrode system. I can't figure out why as there's a 2/0 grounding lug in the meter section. You shouldn't need to make another ground connection in each disconnect section as there's a big-ass grounding bar going across the entire unit for this purpose.

There is an empty stud above the neutral lug that they don't show in the engineering drawing. (this is why I hate these electrical companies who don't provide decent photos of their products). You can attach a ECLK3N lug there which will solve your problem. There might be enough room to remove the #2 lug and replace with a 2/0, haven't tried though. This would also seem to imply that Siemens doesn't think you need to run a 4 wire from here to your main breaker panel.


----------

