What Size Wire

fr8train

Having my services upgraded while I"m renovating my house. I have two 100 amp and one 60 amp service now. Changing over to two 200 amp services, so a total of 400 amps. The service drop from the weather head is about 30 ft. What size wire is it going to take? No, I will not be doing the hookup or any of the electrical, other than helping my electrician buddy pull some wire. ( he asked me to). I live in Central PA.

Speedy Petey

What wire??? The service drop?
That is the POCO's wire. They'll replace it as they see fit. The only codes they follow are their own.

If you are talking about the riser, wouldn't your electrician friend know? If he is an electrician why are you asking here? Not being a jerk, I'm just curious.

To answer accurately we'd need more info, like the demand load. Also, is this a typical 320A residential service? I venture to guess it is.

__________________

MALCO.New.York

I think your "Electrician Buddy" can answer this question correctly. If not........

__________________
Something to One may be Nothing to another!

Ultimate Wisdom---------
http://www.youtube.com/watch?v=OW-cnizLDEE

fr8train

lol, guys, it's ok to admit that you don't know, j/k. I'm just curious cause the POCO was just here to get the lay of the land, etc. I'll see my electrician tomorrow.

The POCO said that I had to supply everything from the weather head down, and they will do the drop from the power line, and hook up at the weather head.

As far as the demand load, let's assume that I'm going to max it out. I'm not going to, just curious.

I'm a curious individual (or maybe I'm just plain nosey) and can learn things quickly. But I am NOT going to attempt this work. I read something in an old post that I firmly believe in. I know just enough to get someone hurt, and that someone would probably be myself or a loved one. I don't want that on my conscience.

mdshunk

Curious to know where you're at in central PA? I'm in Ship.

You're likely to use 4/0 SER if your total demand load is less than 200. You'll build a pipe riser and pull conductors in it if your demand load is higher than that.

fr8train

Shunk, we've talked before, I live in Tower City. I think you said that you used to work up this way at AMP.

I was going to install a dual gang box? One box with 2 meters in it. I currently have 3 meters, one single, and one double. So the total service being installed will be two 200 amp services, total 400 amps. I planned on running conduit for the riser. just looks nicer than a fat ol' wire running down the house, IMO.

mdshunk

What's the third meter that you're losing? An old water heater meter?

You WILL NOT have a "total 400 amps", I feel sure. Installing a 2-gang meter socket, 200 amps per position, does not necessarily mean you're feeding it on the line side with a 400 amp capability. There is a calculation to determine "how much" to feed that line side of the meter socket with. That math is called a "demand load calculation". What was the total requirement when your electrician did his demand load calculation?

fr8train

for the demand load calc, I didn't get that far yet. The 3rd meter I am losing is because previously the building was set up as 3 units. One service for each floor. I am combining the 2nd and 3rd floor into one unit, and leaving the 1st floor as a separate unit.

newenergy

I don't do this, but to me it looks like you start at Article 215, you size the conductor based on 100% of the non-continuous load + 125% of the continuous load, you calculate loads from Article 220, and then size the current carrying conductors from 310.15(B)(6), and the grounding conductor from 250.122 (also possible derations for conductor fill and temperature(? if hot sunny location ?).

I could easily be wrong about some or all of that and would certainly appreciate any corrections.

When I want to do something I don't know enough about to do myself I will have someone qualified do it with me, but that person isn't necessarily going to be teaching me everything he knows. If I do my best to figure out how to do it before the expert gets there, I'll be able to understand what he's doing and ask better questions.

mdshunk

It would be nice if dwelling calcs were that easy, new energy, but they're not. It gets sorta involved.

newenergy

Yeah, I guess that is based off of Article 220, but different cities have different forms for load calculations, right?

I've seen a couple and just googled it and for example, Naperville Illinois has an excel sheet to download http://www.naperville.il.us/loadcalc..._the_Worksheet (link is just to the website, not the download).

I've done some of that preparing for tests, but not IRL.

dlcj

4/0 is what we have installed from the weather head down to te meter. But i have a question to.Why is 4/0 required from w.h to meter but the power comp will pull a 2/0 100 feet from w.h. to the pole?

mdshunk

They work to a different rules book which takes into account conductor cooling from being in free air, and they let their conductors run much hotter. Their code is called the NESC. National Electrical Safety Code. Different than the NEC>

Magnettica

I just got done taking a test on load calcs. What a PITA but I am glad educated on the subject now. Single family general load calc/ multifamily dwelling optional method/ F.L.C. 3HP A/C load vs 6kw electric heat with 7 controlling units/ 6 ranges at 14kw with 27 dishwashers rated at 1200 va/ and 3/4 HP compactor in each of the 20 apartments but no laundry (house load). I thought my head was going to explode.

No, load calculations are not a piece of cake.

__________________
Electrician service in Rahway, Cranford, Clark, Westfield, Mountainside, Scotch Plains, Fanwood, Roselle, Roselle Park, and New Jersey | Same day electrical service and repairs | Licensed and Insured Electrician in Rahway

dlcj

Thanks mdshunk. I guess i can deal with that. Only thing is the last 2 houses we did had underground service and both ran at least 100 feet with standard 2/0 insulated aluminum for each hot and 1/0 for neutral in 3" conduit buried 4'. Its thier rules so i guess its fine but it just looks kind of dumb when u look in the meter socket and see 100' of 2/0 coming in with 4' of 4/0 going out to breaker box. Dont get me wrong i believe the 2/0 is plenty its the 4/0 that seems a little excessive for such a short run.

Speedy Petey

Even if this were just a single 200A service it would need 4/0AL.
If you have 2/0AL run to a 200A service it is the POCO's wire and they likely ran it.

__________________

newenergy

Could the 200A service use 2/0 copper or 4/0 aluminum (or copper clad)?

GSE

Am I missing something, you can use the residential exceptoin on 2 family homes? , and commmercial services? The way i read it he did not have a single dwelling, sems like full size conductors are required

JohnJ0906

That is one thing I got beaten into me during apprenticeship. We did calc after calc after....
When it was time to sit for my Master's exam years later, I found the calcs on the exam easier then the ones we did in school.

__________________
John from Baltimore
"One Day at a Time"
All replies based on the 2008 NEC