200a feed to dwelling, 4/0 max distance?

[PCustoms]

Trying to plan out fixing an issue with the feed to my house. House doesn't currently need 200a, but with the possibility of adding a detached off that panel, adding AC and future EV chargers I think it's best to buy once, cry once.

Can aluminum 4/0 support that load?

What distance?

Can I reduce neutral and ground?

 

[alfredeneuman]

It all depends on the length of the run and the expected load.
The feed to the house should be 3 wire. Grounding is done at the service.

 

[PCustoms]

It all depends on the length of the run and the expected load.
The feed to the house should be 3 wire. Grounding is done at the service.

Meter/main will be close at the pole, 4 wire feed to the house unless I'm missing something.

So my question stands, can 4/0 support 200a to a dwelling, what is the max distance, and can the neutral and ground be reduced?

 

[alfredeneuman]

It all depends on the length of the run and the expected load.

and my prior statement still stands too (not the ground issue)
The ground can't be reduced in any case.

 

[PCustoms]

and my prior statement still stands too (not the ground issue)
The ground can't be reduced in any case.

Apologies if I am the one being dense....

How far of a run can 4/0 aluminum support 200A?

I did a load calc years ago, I think the house is currently at 90A. But, I don't have any AC, EV or shop load currently...so I want to budget 200A service to the house panel, which is a distance, TBD, from where the pole and meter main will be located. If I can only go 100' and get 200A, then that dictates where the meter main can go.

 

[wyliesdiesels]

Why not put the meter main on the house? are you required to put it on a pole in the yard?

 

[fitter30]

Voltage Drop Calculator

Calculate voltage drop in AC or DC circuits, plus learn the formulas to calculate voltage drop for single-phase and three-phase systems.

www.inchcalculator.com

 

[PCustoms]

Why not put the meter main on the house? are you required to put it on a pole in the yard?

Not required, but it it reduces the distance that I'd run to a future shop and has the advantage that I can move the generator inlet away from the house (less noise).

Working on clearing and grading the yard right now, will sketch the layout later.

 

[PCustoms]

Voltage Drop Calculator

Calculate voltage drop in AC or DC circuits, plus learn the formulas to calculate voltage drop for single-phase and three-phase systems.

www.inchcalculator.com

Calculators like this are why I am asking the question.

This one indicates 2.5% drop at 200', which will be no problem. Others indicate 250mcm is needed, or give results that 4/0 may not support 200a even at much shorter distances.

 

[wyliesdiesels]

Not required, but it it reduces the distance that I'd run to a future shop and has the advantage that I can move the generator inlet away from the house (less noise).

Working on clearing and grading the yard right now, will sketch the layout later.

it would be better to have the meter main on the house. that way if you need to add circuits in the future its a lot easier

 

[PCustoms]

it would be better to have the meter main on the house. that way if you need to add circuits in the future its a lot easier

I'm lost, why?

Meter main feeds the house panel as a sub. That panel has room to expand.

Meter main will also feed a 2nd sub in the detached shop.

The transformer is pretty much in the middle of the house and planned shop site.

 

[Bert_]

Meters mounted to the house is fine for stuff in town. It rarely makes sense if your buildings are more spread out

 

[wyliesdiesels]

Calculators like this are why I am asking the question.

This one indicates 2.5% drop at 200', which will be no problem. Others indicate 250mcm is needed, or give results that 4/0 may not support 200a even at much shorter distances.

the voltage drop calculators online are not reliable. they all use different parameters which is why you get different results. some (like the southwire calculator) actually output larger wire sizes than is actually needed. hmmm i wonder why a wire manufacturer would do that??

i actually have the voltage drop math formula posted in #29 on the electrical FAQ sticky found in the link below. so you can calc it yourself

Electrical FAQs

Welcome All I have started this sticky as an FAQ thread for info on the basics that are encountered countless times every week on here. Hopefully this will help some. If u have a topic request, go ahead and post it. And if you have an FAQ you would like covered let me know.... Or if you...

www.garagejournal.com

 

[wyliesdiesels]

I'm lost, why?

Meter main feeds the house panel as a sub. That panel has room to expand.

Meter main will also feed a 2nd sub in the detached shop.

if you have room in your subpanel then disregard

 

[Bert_]

I wouldn't be afraid to go 300'

 

[u2slow]

I recommend the meter at the house also. The utility usually supplies the cable up to a certain distance within the upgrade fee. Also, if it's overhead, it's smaller cable; you only need the #4/0 to get from the weatherhead to the 200A panel. Next size up - 250kcmil is readily available also.

 

[Dagny]

At 300 I usually say I'll do it but you have to get some gas appliances.

 

[mm08822]

Calculators like this are why I am asking the question.

This one indicates 2.5% drop at 200', which will be no problem. Others indicate 250mcm is needed, or give results that 4/0 may not support 200a even at much shorter distances.

Since you have a meter/main, the house would be fed by a feeder from the pole and not service entrance conductors as defined by code definition.

The NEC allows for an exception for residential service entrance conductors. 4/0 Al is only good for 185A as a feeder but 200A as service entrance conductors. I've never seen a wire size calculator take that exception into account.

So the wire size calculator that returned 250mcm is correct. If you used 250mcm to the house from the pole, it would carry the full 200A @ 2% VD for 125'. The real question is do you need all that?

If you also added to that panel mentioned above and chose a 90A feeder to the garage, 2-2-4-6 AL would work for 130' @ 3% VD. (Total of 5% VD.) Again, do you need all that power?

Guestimate your worst-case simultaneous loads first for both house and garage first.

 

[Bert_]

Since you have a meter/main, the house would be fed by a feeder from the pole and not service entrance conductors as defined by code definition.

The NEC allows for an exception for residential service entrance conductors. 4/0 Al is only good for 185A as a feeder but 200A as service entrance conductors. I've never seen a wire size calculator take that exception into account.

So the wire size calculator that returned 250mcm is correct. If you used 250mcm to the house from the pole, it would carry the full 200A @ 2% VD for 125'. The real question is do you need all that?

If you also added to that panel mentioned above and chose a 90A feeder to the garage, 2-2-4-6 AL would work for 130' @ 3% VD. (Total of 5% VD.) Again, do you need all that power?

Guestimate your worst-case simultaneous loads first for both house and garage first.

If your load is 180a or less you can still use the 4/0. No 180A breakers so you can round up

 

[u2slow]

If your load is 180a or less you can still use the 4/0. No 180A breakers so you can round up

There are 175A breakers though.

https://www.amazon.ca/dp/B00CONRDI8/?tag=atomicindus04-20

 

[ArcReactorKC]

Meter/main will be close at the pole, 4 wire feed to the house unless I'm missing something.

So my question stands, can 4/0 support 200a to a dwelling, what is the max distance, and can the neutral and ground be reduced?

I didn't see where it was definitively answered but NO you cannot reduce the neutral.

 

[alfredeneuman]

I didn't see where it was definitively answered but NO you cannot reduce the neutral.

NEC 215.2 Grounded Conductor
"The grounded conductor shall not be smaller than that required by 250.122"

That means the neutral can't be smaller than the appropriate equipment ground for the feeder. In the case of a 200A circuit it would be a #4 aluminum or #6 copper.

 

[Bert_]

There are 175A breakers though.

https://www.amazon.ca/dp/B00CONRDI8/?tag=atomicindus04-20

There are also 20A breakers and 60A breakers, ect. Those sizes don't matter just like a 175A.

Anything under 800A you are allowed to round up if there is not a breaker with a rating that matches the wire.

 

[ArcReactorKC]

NEC 215.2 Grounded Conductor
"The grounded conductor shall not be smaller than that required by 250.122"

That means the neutral can't be smaller than the appropriate equipment ground for the feeder. In the case of a 200A circuit it would be a #4 aluminum or #6 copper.

220.61(A), “Basic Calculation”, states that a “feeder or service neutral load shall be the maximum unbalance of the load determined by this article [220]. The maximum unbalanced load shall be the maximum net calculated load between the neutral conductor and any one ungrounded conductor [hots]”. What this means is that the neutral conductor can’t be smaller than the unbalanced load that it could carry from the neutral to ungrounded conductors.


It also has to be sized to the available fault current. But that is a whole 'nother ball of wax.

 

[alfredeneuman]

What this means is that the neutral conductor can’t be smaller than the unbalanced load that it could carry from the neutral to ungrounded conductors.

If the load consisted of all line to line connections then there would be zero current on the neutral. If the line to neutral load was 50A then a #6 would handle it easily.

 

[ArcReactorKC]

If the load consisted of all line to line connections then there would be zero current on the neutral. If the line to neutral load was 50A then a #6 would handle it easily.

Correct, in what residence are all loads line to line?

 

[alfredeneuman]

Correct, in what residence are all loads line to line?

We're not talking about a residence.
We're discussing a shop where the likelihood of a greater percentage of the loads will be L-L.
Anyhow it was just an example.
The circuit is the feeder, which combines all the circuits regardless of their individual neutral loads.
Line to neutral circuits from the different legs cancel each other out (subtractive vs additive)
A 50A unbalanced load isn't uncommon.

 

[ArcReactorKC]

We're not talking about a residence.
We're discussing a shop where the likelihood of a greater percentage of the loads will be L-L.
Anyhow it was just an example.
The circuit is the feeder, which combines all the circuits regardless of their individual neutral loads.
Line to neutral circuits from the different legs cancel each other out (subtractive vs additive)
A 50A unbalanced load isn't uncommon.

I don't know if you are a licensed/experienced electrician but regardless this was the first post.
I'm more than aware of how loads work. I literally own/operate a paralleling switchgear company.

 

[mm08822]

I didn't see where it was definitively answered but NO you cannot reduce the neutral.

The neutral can be reduced with calculations performed to justify the smaller - examples are provided in NEC Informative Annex D. I don't think anyone is suggesting anything smaller than 2 sizes below the ungrounded conductor sizes. e.g. - 4/0 -> 2/0. The size reductions on this order are typical of manufactured cable assemblies, SEU, SER, MHF, etc.

The calculations assume all general loads are on one leg. With a panel buss alternating "phases" and the typical practice of contiguous stacking of cb's in a panel, it would be a rarity for all single phase loads to be on one leg.

220.61(A), “Basic Calculation”, states that a “feeder or service neutral load shall be the maximum unbalance of the load determined by this article [220]. The maximum unbalanced load shall be the maximum net calculated load between the neutral conductor and any one ungrounded conductor [hots]”. What this means is that the neutral conductor can’t be smaller than the unbalanced load that it could carry from the neutral to ungrounded conductors.


It also has to be sized to the available fault current. But that is a whole 'nother ball of wax.

Assuming the calculations mentioned above resulted in a very small neutral size, there is a minimum size required. It is the same size as the grounding conductor. There is no ball of wax as both neutral and grounding conductors are sized to provide an adequate fault path to trip OCP regardless of the fault mode.

 

[mm08822]

If your load is 180a or less you can still use the 4/0. No 180A breakers so you can round up

Interestingly enough, at 180 Amp max load, 4/0 Al provides a 2% VD @ 125'. 250mcm AL only provides another 20 Amps for same VD/length.

 

[alfredeneuman]

I apologize for the mistake of the house to the outbuilding's feeder comment.
The rest is true though. What scenario do you picture where all the load will be on one leg?
The loads on the individual legs will largely cancel out the neutral current at the panel.
Remember, you said "NO you cannot reduce the neutral"

 

[alfredeneuman]

I don't know if you are a licensed/experienced electrician but regardless this was the first post.
I'm more than aware of how loads work. I literally own/operate a paralleling switchgear company.

I'm just a retired Electrical Contractor with 45+ years in the trade.
From the description of your position you should know better how loads work than this.

 

[PCustoms]

Bumping thread. Current arial feed is at 90'. Add another 30' up the pole and 10' at the house end plus a generous fudge factor and it looks like I'd need 150' point to point for the longest possible run.

 

[jim111]

At that distance, you are fine with 4/0 4/0 2/0 4 underground MHF

 

[PCustoms]

At that distance, you are fine with 4/0 4/0 2/0 4 underground MHF

That's what I figured.

I forget, can XHHW-2 go underground in conduit and inside the house?

 

[mike93lx]

That's what I figured.

I forget, can XHHW-2 go underground in conduit and inside the house?

Yes, as can mhf and some URD

 

[PCustoms]

Yes, as can mhf and some URD

That's what I thought.

Read back through the thread and am still confused about the neutral.

If I need 4/0, looks like buying individual cables saves me some $$.

If I need 4/0, 4/0, 2/0, 4 then MHF might be cheaper.

 

[mike93lx]

That's what I thought.

Read back through the thread and am still confused about the neutral.

If I need 4/0, looks like buying individual cables saves me some $$.

If I need 4/0, 4/0, 2/0, 4 then MHF might be cheaper.

There is effectively no chance of overload 2/0 neutral. You'd have to try like hell to and even then, it wouldn't be easy

 

[PCustoms]

There is effectively no chance of overload 2/0 neutral. You'd have to try like hell to and even then, it wouldn't be easy

OK. So 4/0, 4/0, 2/0 from pole down to meter/main, then 4/0, 4/0, 2/0, 4 on to house.

Total run is less then 150'.

Buying individual XHHW-2 instead of URD and MHF seems to come out cheaper. Need to do this on a computer and not my phone as I take a beverage break though.

 

[mike93lx]

Don't forget wire and rods for grounding at both the main and house