# Size this service entrance



## 3DDesign (Oct 25, 2014)

Four Unit apartment building.

* Five gang meter socket feeding five 100 amp, 120/240V single phase panels, one meter is the "house" meter.
* Apartments are 900 sq ft each - four units
* Each Apartment has 240V Range, Hot Water, Clothes Dryer, Central A/C, gas furnace
* Full kitchen with Dishwasher & Microwave, 
*House meter has minimal lighting, two coin operated Washers and 240V Dryers

The project hasn't started yet. I met with the electrical inspector this week. 
I'll post what he said after I see your results.

What size wire would you run to feed the five gang meter base?


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## telsa (May 22, 2015)

This is even worse than a homework question.

200A is out of the question.

So you're left with a 400A frame size service.

The wire size is dictated by the Poco where I roam.

But, out here, we'd be setting a cheesy 400A Rayco NEMA3R box with T fuses and a bolt switch... with the Poco setting current transformers, to boot.

( We'd be... most likely... stuck with a 3-phase Service, too. You're in that borderline load situation. ) 

The feed would be an (U/G) Service Lateral, too.

These values would be pulled from tables....

You east coast guys have it made.


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## HackWork (Oct 2, 2009)

The thing I find odd is that there's going to be two rental washers and two rental dryers in a four unit apartment building in which each unit is set up for a washer and dryer inside.


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## splatz (May 23, 2015)

HackWork said:


> The thing I find odd is that there's going to be two rental washers and two rental dryers in a four unit apartment building in which each unit is set up for a washer and dryer inside.


That is strange. 

Now that you point it out, I think I have heard about this, those rental washers and dryers might be a front for money laundering.


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## 3DDesign (Oct 25, 2014)

telsa said:


> This is even worse than a homework question.
> 
> 200A is out of the question.
> 
> ...


The apartments are set up dryers but not installed, the tenant would need to own it. If they don't own one, they would use the coin operated.

I forgot to mention, this is overhead.
The PoCo only requires inspection, they don't dictate wire size here.


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## 3DDesign (Oct 25, 2014)

telsa said:


> This is even worse than a homework question.
> 
> .


I thought it might be a good exercise for the students.
I've already calculated the load and had it approved by the local inspector.
The meter base can handle 600mcm on the line side
I just wanted to see what others come up with.


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## sbrn33 (Mar 15, 2007)

I I think 300 would be OK but I would just throw in 400 ampere wire just because the cost difference is small and the meter bank is going to be the same. 
Oh I just noticed where your lugs are only rated 600. That is what I would use. That give you 340 which is plenty. I am using AL.


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## MTW (Aug 28, 2013)

Off the top of my head, the load calc will come in around 300 amps.


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## 3DDesign (Oct 25, 2014)

MTW said:


> Off the top of my head, the load calc will come in around 300 amps.


Excellent guess. 350 MCM Copper is what we agreed upon.


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## sbrn33 (Mar 15, 2007)

3DDesign said:


> Excellent guess. 350 MCM Copper is what we agreed upon.


So you are willing to spend an extra $700 just run copper over aluminum?


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## 3DDesign (Oct 25, 2014)

sbrn33 said:


> So you are willing to spend an extra $700 just run copper over aluminum?


300 amp is what we agreed on. I'll compare prices this week.
Thanks for reminding me to do that.


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## sbrn33 (Mar 15, 2007)

That will be interesting, it could be less but just a quick internet search had 350 CU at $7 and 500 AL at $2. I was figuring a 15 foot riser. 
AL se into the units I assume.


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