400 amp residential service

[Besoeker]

Folks, thank you for the interesting responses.

 

[kwired]

not very unusual to have 3 heat pump w/ 10-15kw heat strips each, 2 water heaters, clothes dryer, electric range, etc.

So not very likely for all this to be going at the same time?

Well it is upon family's return from vacation

Correct that it seldom is all going at one time. But there is occasions when it is.

Good example I have seen is rural churches. If you looked at monthly billing you would think there is no way that building needs a 400 amp service, but it sits there most of the time with very little load. Every Sunday there is high demand for maybe an hour up to 4 hours, and maybe a few other times here and there with similar demand cycles. You need to be able to handle that demand when it is there.

 

[ddecart]

Ignorant Brit.............
What kind of residence needs a 400A service?
Typically here we have 40A or 60A.

I have single breakers that big

My house is all-electric. No gas. No propane.
The house is approx 3000 sq ft, plus a 1000 sq ft heated garage, 2700 sq ft of basement. Plus a 1200 sq ft outbuilding with 800 sq ft of potential living space above.
3 water heaters (including the garage, which is limited-use and seasonal)
House is heated/cooled with 7 mini-split heads and 2 outdoor units (a handful of 500W baseboards for extreme cold days that I don't expect to use)
Attached garage is in-floor radiant via a 13kW tankless water heater (that'll never see that load)
Basement and outbuilding are prepped for hydronic in-floor as well

I'm on a dedicated transformer... can't recall the size.
400A service to the meter.
Two 200A panels immediately inside the garage at the meter.
One panel serves the garage side of the house, and the basement wood shop
The other panel feeds a remote 200A panel that handles the other side of the house and feeds the outbuilding.

Am I going to draw anywhere close to 400A at a time? Heck no.
It is possible to draw more than 200A at one time? Perhaps

But I need to get the wires run from the meter to the panels first

 

[mwm1752]

And this is why I despise reading the NEC. It says little and references itself ad nauseum.
Service conductors entering a building shall be installed in accordance with 230.6 or protected by a raceway method identified in 230.43.

230.43 says Service Entrance Cable is good to go....kind of. It says "Service entrance cable is ok if you use the applicable parts of this code".
230.6 seems to be irrelevant (determining if conductors entering a building are outside of a building?)

By that, exposed service entrance cable should be a-ok.

Of course, there's the "if subject to physical damage" caveat, which appears to be left to the whims of the individual inspector.

I would not consider SER cable a raceway & inspectors should not inspect using whims as code but should read the code for what it says

 

[Unbridled]

Hi, I am hoping some one has some pics of a 400 amp service they have done( and are willing to post). This will be my first one. I was wanting to come out of the meter can with two sets of 4/0 alum SE cable with side by side 200 panels directly behind meter can. All the pics i can find all have pvc or have a gutter put in. I was hoping to see how it looks before going ahead. Thanks

Why make it so difficult. 2-2" nipples out the back of the meter, through the exterior wall, installed wide enough to simply nipple into your panels directly though the wall!!

 

[Besoeker]

I have single breakers that big

Well, yes.
I've engineered systems with breakers rated at 2000A.
But not for residential applications.

 

[ddecart]

I would not consider SER cable a raceway & inspectors should not inspect using whims as code but should read the code for what it says

Then we need to look at 230.43 which spells out service entrance cable as a method. No whims involved.

 

[mwm1752]

Then we need to look at 230.43 which spells out service entrance cable as a method. No whims involved.

still didn't read - yes - SER Cable is in 230.43 but you shall use a raceway to protect it so your statement of "By that, exposed service entrance cable should be a-ok" is not correct & if you keep the ser outside of the building it in underground raceway it is not compliant.
or protected by a raceway method identified in 230.43.

 

[petersonra]

Well, yes.
I've engineered systems with breakers rated at 2000A.
But not for residential applications.

the largest I have used as well. you get above that and you are out of the realm of MCCB for the most part. I think someone makes a 2400 A MCCB but that is the largest I have heard of.

 

[ddecart]

still didn't read - yes - SER Cable is in 230.43 but you shall use a raceway to protect it so your statement of "By that, exposed service entrance cable should be a-ok" is not correct & if you keep the ser outside of the building it in underground raceway it is not compliant.
or protected by a raceway method identified in 230.43.

The issue is that 230.43 has nothing to do with raceways. The word "raceway" doesn't even appear. So after multiple references to other paragraphs, we end up on one that's irrelevant for the purpose for which it was referenced.

Unless, of course, we look at 230.43 and realise that service entrance cables are mentioned in the same list as pretty much every sort of "conduit" available. Regardless of the topic, that would suggest that, for example, ENT and SE cables are equivalent in the eyes of the code in some circumstances.

 

[ggunn]

Ignorant Brit.............
What kind of residence needs a 400A service?
Typically here we have 40A or 60A.

Yesterday I designed a PV system for a residence that had a 600A service (three 200A service discos). The most common size I see is 200A, but bigger ones are out there. Could a difference be that your loads are all 230V while most US household loads are 120V?

 

[Coppersmith]

http://www.milbankworks.com/catalogs/u5890-5895.pdf

Check with utility and ahj, but I have used one of these (very similar anyway) for a 400A residence, to feed two 200A load centers. (if I recall correctly the one I used had one breaker on each side)
It's a Milbank 320 meter socket/combo with two 200A breakers

The meter is rated 320 amp. There are two 200 amp breakers. Is this a 320 amp service or a 400 amp service? When doing the load calc does it have to be 320 amps or less to use this equipment? :?

 

[kwired]

Could a difference be that your loads are all 230V while most US household loads are 120V?

But very few of those US households are on a 120 volt two wire supply, they are on 120/240 or 120/208 multiwire supplies and the 120 volt load is somewhat balanced across the higher voltage. Net VA for houses with similar appliances is still similar.

Is also common in US to provide 200 amps capacity supply circuit anymore even if the actual demand is under 100 amps. My house has 3 ton heat pump with 15kVA resistance heat as backup heat, 4500 watt water heater, 13.5 kW electric range, 5.5 kW dryer, 1 HP well pump, 1700ish square feet of living space, plus majority of full basement is finished. I have 200 amps of service capacity run to it, but I bet it seldom ever sees more then 60 amps of current, if it does it doesn't last for very long. If I had a 60 amp service main breaker I would expect it might trip sometimes, but I would bet a 100 amp main would seldom if ever trip.

 

[mwm1752]

The issue is that 230.43 has nothing to do with raceways. The word "raceway" doesn't even appear. So after multiple references to other paragraphs, we end up on one that's irrelevant for the purpose for which it was referenced.

Unless, of course, we look at 230.43 and realise that service entrance cables are mentioned in the same list as pretty much every sort of "conduit" available. Regardless of the topic, that would suggest that, for example, ENT and SE cables are equivalent in the eyes of the code in some circumstances.

I now have no clue on the point you are trying to make & it has no bearing on my comments, you seem to not comprehend the meaning I am trying to convey -- so "you win" ---

 

[ddecart]

I now have no clue on the point you are trying to make & it has no bearing on my comments, you seem to not comprehend the meaning I am trying to convey -- so "you win" ---

Interesting, since I'm not trying to "win". I'm merely trying to understand my original question pertaining to the appropriate means of transmitting electrons from a meter box on the outside of a wall, to an electrical panel on the opposite side, and back. I'll recap for you, so you can perhaps see where my question is at and where the code is/is not providing useful information.

You said

If the inside 200 amp breakers are your service disconnect 230.32

Indeed they are 200A breakers.
Let’s see if 230.32 answer the question asked:
The question was: Does 4/0 (SE) exposed really cut it? Does it need to be in a conduit?
Alternately stated: If I run 4/0 Aluminum SE, does it need to be in a conduit?

Actually, 230.32 provides no new information that’s not found elsewhere. It actually says, in so many words, “go away, this isn’t where to find the information you came here for”:

230.32: “Service conductors entering a building or other structure shall be installed in accordance with 230.6 or protected by a raceway wiring method identified in 230.43”

So off we go with 2 places to check.

Let’s look first at 230.6:

230.6 Conductors Considered Outside the Building
Conductors shall be considered outside of a building or other structure under any of the following conditions:
(1) Where installed under not less than 50 mm (2 in.) of concrete beneath a building or other structure.
(2) Where installed within a building or other structure in a raceway that is encased in concrete or brick not less than 50 mm (2 in.) thick
(3) Where installed in any vault that meets the construction requirements of Article 450, Part III
(4) Where installed in conduit and under not less than 450 mm (18 in.) of earth beneath a building or other structure
(5) Where installed in overhead service masts on the outside surface of the building travelling through the eave of that building to meet the requirements of 230.24.

Hmmm…”shall be installed in accordance with 230.6”
Actually, 230.6 merely categorizes methods of installation and answers the question “If I do X, are my conductors considered outside of the building?”

Am I interested in knowing whether or not my conductors are considered outside of the building? Not so much. Therefore, it’s straightforward to conclude that 230.6 does not provide immediately relevant information to answer the question “If I run 4/0 Aluminum SE, does it need to be in a conduit?”

The best I can tell so far, is that my exposed 4/0 SE is probably considered “outside the building” per 230.6. Good to know? Must be.

So knowing that my exposed 4/0 is “outside the building” I’m back looking at 230.32. The first part was useless as a direct answer to my question, so let’s head off on a quest of looking at 230.43. Surely it has the nugget that we need….. “protected by a raceway wiring method identified in 230.43”. Raceway wiring methods. That’s the ticket!

230.43 Wiring Methods for 600 volts, Nominal, or Less

Service entrance conductors shall be installed in accordance with the applicable requirements of this Code covering the type of wiring method used and shall be limited to the following methods:
(1) Open wiring on insulators
(2) Type IGS cable
(3) Rigid Metal Conduit
(4) Intermediate Metal Conduit
(5) Electrical Metallic Tubing
(6) Electrical Nonmetallic Tubing (ENT)
(7) Service-entrance cables
(8) Wireways
(9) Busways
(10) Auxillary gutters
(11) Rigid Polyvinyl Chloride conduit (PVC)
(12) Cablebus
(13) Type MC Cable
(14) Mineral-Insulated, metal-sheathed cable
(15) Flexible metal conduit not over 1.8 m (6 ft) long or liquidtight flexible metal conduit not over 1.8 m (6 ft) long between raceways, or between raceway and service equipment bonduing jumper routed with the flexible metal conduit according to the provisions of 250.102(A), (B), (C), and (E)
(16) Liquidtight flexible nonmetallic conduit
(17) High density polyethylene conduit (HDPE)
(18) Nonmetallic underground conduit with conductors (NUCC)
(19) Reinforced thermosetting resin conduit (RTRC)


Quite a mouthful there.

So having determined from 230.6 that I have conductors that are considered outside of a building, 230.43 tells me that that among the varied list of wiring methods (which are actually just means of protecting wires, and not methods of wiring, but that’s semantics) that SERVICE ENTRANCE CABLES are good to go. Interestingly enough, it makes no reference to “outside the building”.

Does it tell me that they need to be in a conduit? Nope. 230.43 doesn’t even mention the word “raceway”, which is odd since 230.32 seemed to think it was leading me to a list of “raceway wiring methods”. Perhaps I’m to conclude based on the text of 230.32 that the list in 230.43 are ALL considered “raceway” methods.

So from all of that jumping around, I’ve concluded:
1) My conductors are outside of the building
2) Service Entrance Cable is listed among approved wiring methods for service-entrance conductors for under 600 volts.

You proclaimed that

I would not consider SER cable a raceway & inspectors should not inspect using whims as code but should read the code for what it says

It seems as though the code would suggest that you are using whims as code, since the actual code you referenced does not say or suggest “SER is not considered a raceway”. I would think a reasonable person of average intelligence would discern from that limited extract of NEC that SER is, indeed, a raceway method.

In other words, the code suggests that you were mistaken with your consideration of SER.

Perhaps it’s not permitted by some other section?

 

[kwired]

Interesting, since I'm not trying to "win". I'm merely trying to understand my original question pertaining to the appropriate means of transmitting electrons from a meter box on the outside of a wall, to an electrical panel on the opposite side, and back. I'll recap for you, so you can perhaps see where my question is at and where the code is/is not providing useful information.

You said


Indeed they are 200A breakers.
Let’s see if 230.32 answer the question asked:
The question was: Does 4/0 (SE) exposed really cut it? Does it need to be in a conduit?
Alternately stated: If I run 4/0 Aluminum SE, does it need to be in a conduit?

Actually, 230.32 provides no new information that’s not found elsewhere. It actually says, in so many words, “go away, this isn’t where to find the information you came here for”:

230.32: “Service conductors entering a building or other structure shall be installed in accordance with 230.6 or protected by a raceway wiring method identified in 230.43”

So off we go with 2 places to check.

Let’s look first at 230.6:

230.6 Conductors Considered Outside the Building
Conductors shall be considered outside of a building or other structure under any of the following conditions:
(1) Where installed under not less than 50 mm (2 in.) of concrete beneath a building or other structure.
(2) Where installed within a building or other structure in a raceway that is encased in concrete or brick not less than 50 mm (2 in.) thick
(3) Where installed in any vault that meets the construction requirements of Article 450, Part III
(4) Where installed in conduit and under not less than 450 mm (18 in.) of earth beneath a building or other structure
(5) Where installed in overhead service masts on the outside surface of the building travelling through the eave of that building to meet the requirements of 230.24.

Hmmm…”shall be installed in accordance with 230.6”
Actually, 230.6 merely categorizes methods of installation and answers the question “If I do X, are my conductors considered outside of the building?”

Am I interested in knowing whether or not my conductors are considered outside of the building? Not so much. Therefore, it’s straightforward to conclude that 230.6 does not provide immediately relevant information to answer the question “If I run 4/0 Aluminum SE, does it need to be in a conduit?”

The best I can tell so far, is that my exposed 4/0 SE is probably considered “outside the building” per 230.6. Good to know? Must be.

So knowing that my exposed 4/0 is “outside the building” I’m back looking at 230.32. The first part was useless as a direct answer to my question, so let’s head off on a quest of looking at 230.43. Surely it has the nugget that we need….. “protected by a raceway wiring method identified in 230.43”. Raceway wiring methods. That’s the ticket!

230.43 Wiring Methods for 600 volts, Nominal, or Less

Service entrance conductors shall be installed in accordance with the applicable requirements of this Code covering the type of wiring method used and shall be limited to the following methods:
(1) Open wiring on insulators
(2) Type IGS cable
(3) Rigid Metal Conduit
(4) Intermediate Metal Conduit
(5) Electrical Metallic Tubing
(6) Electrical Nonmetallic Tubing (ENT)
(7) Service-entrance cables
(8) Wireways
(9) Busways
(10) Auxillary gutters
(11) Rigid Polyvinyl Chloride conduit (PVC)
(12) Cablebus
(13) Type MC Cable
(14) Mineral-Insulated, metal-sheathed cable
(15) Flexible metal conduit not over 1.8 m (6 ft) long or liquidtight flexible metal conduit not over 1.8 m (6 ft) long between raceways, or between raceway and service equipment bonduing jumper routed with the flexible metal conduit according to the provisions of 250.102(A), (B), (C), and (E)
(16) Liquidtight flexible nonmetallic conduit
(17) High density polyethylene conduit (HDPE)
(18) Nonmetallic underground conduit with conductors (NUCC)
(19) Reinforced thermosetting resin conduit (RTRC)


Quite a mouthful there.

So having determined from 230.6 that I have conductors that are considered outside of a building, 230.43 tells me that that among the varied list of wiring methods (which are actually just means of protecting wires, and not methods of wiring, but that’s semantics) that SERVICE ENTRANCE CABLES are good to go. Interestingly enough, it makes no reference to “outside the building”.

Does it tell me that they need to be in a conduit? Nope. 230.43 doesn’t even mention the word “raceway”, which is odd since 230.32 seemed to think it was leading me to a list of “raceway wiring methods”. Perhaps I’m to conclude based on the text of 230.32 that the list in 230.43 are ALL considered “raceway” methods.

So from all of that jumping around, I’ve concluded:
1) My conductors are outside of the building
2) Service Entrance Cable is listed among approved wiring methods for service-entrance conductors for under 600 volts.

You proclaimed that

It seems as though the code would suggest that you are using whims as code, since the actual code you referenced does not say or suggest “SER is not considered a raceway”. I would think a reasonable person of average intelligence would discern from that limited extract of NEC that SER is, indeed, a raceway method.

In other words, the code suggests that you were mistaken with your consideration of SER.

Perhaps it’s not permitted by some other section?

Some places maybe have local amendments restricting use of SE cable. Otherwise my simple reply is -why is it called Service Entrance Cable if it can't be used for service entrance purposes?:huh:

 

[mwm1752]

[h=2]400 amp residential service[/h]

Hi, I am hoping some one has some pics of a 400 amp service they have done( and are willing to post). This will be my first one. I was wanting to come out of the meter can with two sets of 4/0 alum SE cable with side by side 200 panels directly behind meter can. All the pics i can find all have pvc or have a gutter put in. I was hoping to see how it looks before going ahead. Thanks

I can see now that this can also be looked at as a free standing service which you are discussing & not mounted on a exterior structure wall which I was discussing

So lets discuss your view with what little we know about this free standing service --​

338.12 Uses Not Permitted. (A) Service-Entrance Cable. Service-entrance cable (SE) shall not be used under the following conditions or in the following locations:
(1) Where subject to physical damage unless protected in accordance with 230.50(B) -- This is now a judgement call as subject to physical damage is not a specifically defined location in the Code, If not needed, then the raceway's listed are not required which now comes to full circle of your comment "which appears to be left to the whims of the individual inspector."
230.50 Protection Against Physical Damage
(B)Service-Entrance Cables. Service-entrance cables, where subject to physical damage, shall be protected by any of the following:
(1) Rigid metal conduit (RMC)
(2) Intermediate metal conduit (IMC)
(3) Schedule 80 PVC conduit
(4) Electrical metallic tubing (EMT)
(5) Reinforced thermosetting resin conduit (RTRC)
(6) Other approved means
(2) Underground with or without a raceway
(3) For exterior branch circuits and feeder wiring unless the installation complies with the provisions of Part I of Article 225 and is supported in accordance with 334.30 or is used as messenger-supported wiring as permitted in Part II of Article 396
Part I of Article 225 -- does not apply as this is not on a exterior structure wall
225.10 Wiring on Buildings (or Other Structures). The installation of outside wiring on surfaces of buildings (or other structures) shall be permitted for circuits not exceeding 1000 volts, nominal, as the following:
(1) Auxiliary gutters
(2) Busways
(3) Cable trays
(4) Cablebus
(5) Electrical metallic tubing (EMT)
(6) Flexible metal conduit (FMC)
(7) Intermediate metal conduit (IMC)
(8) Liquidtight flexible metal conduit (LFMC)
(9) Liquidtight flexible nonmetallic conduit (LFNC)
(10) Messenger-supported wiring
(11) Multiconductor cable
(12) Open wiring on insulators
(13) Reinforced thermosetting resin conduit (RTRC)
(14) Rigid metal conduit (RMC)
(15) Rigid polyvinyl chloride conduit (PVC)
(16) Type MC cable
(17) Type MI cable
(18) Type UF cable
(19) Wireways

simply if the 200 amp breakers are inside the building then the wiring method to reach them is also inside -- never said SER could not be used but if it was it would be protected once it entered the building. The service drop to the meter was not part of my comments I was describing the wiring method on the line side of the meter but the continuation to interior service disconnects was my intended discussion to your "By that, exposed service entrance cable should be a-ok" -- the only reason 230.6 was involved was due to interior service disconnects which became the topic of discussion IMO -- the question as I saw it was about wiring methods to inside service disconnects - Thank you for clarifying your view

 

[kwired]

simply if the 200 amp breakers are inside the building then the wiring method to reach them is also inside -- never said SER could not be used but if it was it would be protected once it entered the building. The service drop to the meter was not part of my comments I was describing the wiring method on the line side of the meter but the continuation to interior service disconnects was my intended discussion to your "By that, exposed service entrance cable should be a-ok" -- the only reason 230.6 was involved was due to interior service disconnects which became the topic of discussion IMO -- the question as I saw it was about wiring methods to inside service disconnects - Thank you for clarifying your view

My question is protected from what?

If you are simply passing through wall to panel on opposite side or maybe through a sill and then down a coupe feet to a panel - the risk of physical abuse often is not that great inside vs what it may be on the outside.

 

[Mikros]

The meter is rated 320 amp. There are two 200 amp breakers. Is this a 320 amp service or a 400 amp service? When doing the load calc does it have to be 320 amps or less to use this equipment? :?

This was a very long time ago.... I believe it was the case that the utility company told us "this is how we do 400A residential metering" but I also doubt that the load calc was over 320A. Part of the reason I threw in the note to check with your ahj, they might want to see a load calc, and if they insist on a higher rated meter socket than 320A you may have to go back to the utility company and see what they have to offer as a solution. Basically get your ducks in a row before buying/installing.

 

[kwired]

This was a very long time ago.... I believe it was the case that the utility company told us "this is how we do 400A residential metering" but I also doubt that the load calc was over 320A. Part of the reason I threw in the note to check with your ahj, they might want to see a load calc, and if they insist on a higher rated meter socket than 320A you may have to go back to the utility company and see what they have to offer as a solution. Basically get your ducks in a row before buying/installing.

And if the load is more then 320 amps (regardless of occupancy type or voltage/number of phases) most POCO's seem to prefer CT metering even if there is self contained metering available for the application. Less components for them to have to keep in stock is likely one of the main reasons.