Exploring options for 600A Service conductors

[Gshock]

Good Morning, I am completely new here so take it easy on me . I normally just argue stuff like this out with my partner, but I figured I would try out the forum and get a fresh perspective on things. We are installing a new 600A service for a multifamily rehab (3apt + public) and exploring are our options for service conductors. My initial thought was just to go with parallel 350s (AL by the way) in 2 x 2 1/2 conduit and call it a day. My partner on the other hand thinks with should go with 3 x 4/0 SEU parallel and eliminate the conduit? Other than cost, which is all he is arguing, do you guys see any advantage if one option over the other?

 

[iwire]

If you want to save the most money possible it is absolutely essential you have the NEC calculated load for this service.

There will be no need to size the conductors for 600 amps if the calculated load is say 350 amps and you design it wisely.


As far as the cable vs conduit question you might as well ask if Chevy or Ford is the better truck.

Baring local rules it is just personal choice.

 

[Dennis Alwon]

Good Morning, I am completely new here so take it easy on me . I normally just argue stuff like this out with my partner, but I figured I would try out the forum and get a fresh perspective on things. We are installing a new 600A service for a multifamily rehab (3apt + public) and exploring are our options for service conductors. My initial thought was just to go with parallel 350s (AL by the way) in 2 x 2 1/2 conduit and call it a day. My partner on the other hand thinks with should go with 3 x 4/0 SEU parallel and eliminate the conduit? Other than cost, which is all he is arguing, do you guys see any advantage if one option over the other?

First I think you m T310.15(B)ant USE not SEU. I don't believe you can use 4/0 x3 since the service cable would not fall under the residential table for wire sizes. Here is 310.15(B)(7) in the 2014 but it was just reworded to clarify other code years

(7) 120/240-Volt, Single-Phase Dwelling Services and Feeders. For one-family dwellings and the individual dwelling units of two-family and multifamily dwellings, service and feeder conductors supplied by a single-phase, 120/240-volt system shall be permitted be sized in accordance with 310.15(B)(7)(1) through (4).
(1) For a service rated 100 through 400 A, the service conductors supplying the entire load associated with a one-family dwelling, or the service conductors supplying the entire load associated with an individual dwelling unit in a two-family or multifamily dwelling, shall be permitted to have an ampacity not less than 83 percent of the service rating.

 

[iwire]

Dennis, I assumed overhead service with SE-U, maybe I am wrong.

 

[Dennis Alwon]

First I think you m T310.15(B)ant USE not SEU. I don't believe you can use 4/0 x3 since the service cable would not fall under the residential table for wire sizes. Here is 310.15(B)(7) in the 2014 but it was just reworded to clarify other code years

Iwire is correct that you don't have to size the conductors to the full 600 amps however IMO then you may be short changing the customer. That being said the odds of overloading the apts by doing a calculation is next to nil, assuming these are not huge units where large amnount of additions etc can take place

 

[Dennis Alwon]

Dennis, I assumed overhead service with SE-U, maybe I am wrong.

You are probably correct- I saw conduit and assumed ug. :thumbsup:

 

[iwire]

you don't have to size the conductors to the full 600 amps however IMO then you may be short changing the customer.

If the customer is requesting a 600 amp service I fully agree with you. I would even argue using the reduced sizes for dwellings would be cheating them.

However if the customer just wants their building wired safely and code compliantly any size conductors above the calculated load are fine and also typical in multifamily dwellings.

 

[Gshock]

Wow you guys are quick, This is great I just stepped away for coffee and all these replies. So let me answer some of the questions.
1. Yes it is a overhead service
2. We did the load calc (started another argument when we did it) but we came in around 525 or 540a(can't remember now,but I will grab the project docs and check). The bldg has 1 large 1500sqft apt and 2 small 900sqft units. They are all All electric with (Range, Dryer, Water heater, and Heatpump with the supplemental heat thingys).

 

[infinity]

For me I would use two conduits with the appropriately sized parallel conductors.

 

[Gshock]

If the customer is requesting a 600 amp service I fully agree with you. I would even argue using the reduced sizes for dwellings would be cheating them.

However if the customer just wants their building wired safely and code compliantly any size conductors above the calculated load are fine and also typical in multifamily dwellings.

Yes thats pretty much my business model. I never (well never may not be truthful ), but lets say I don't like under-sizing and with Multifamily dwellings like this I am especially careful

 

[Gshock]

For me I would use two conduits with the appropriately sized parallel conductors.

Yup, thats was exactly my thought as well 2 conduits. After talking to you guys though I thinking I may actually be able to go with 300s or even 250s instead of 350s :slaphead: I'm gonna double check my calcs here in a sec. But I think the consensus is definitely no 4/0 x3. This was great I like the ability to chat with others in the field quickly like this and o get other thoughts on it. I'm not old but we use to only be able to do this at the supply house... or in the bar

 

[iwire]

For me I would use two conduits with the appropriately sized parallel conductors.

The real question would be how would you do it when the money is directly coming out of your pocket as a business owner?

How was it priced etc?

I have seen pictures of your work, it is outstanding and clearly you work in a segment that puts looks ahead of pricing. That is far from normal, at least in my experience.

If I was an EC I would not be quick to be generous with nice conduit with customer that nickle and dimed me on the original price which is generally what I see.

 

[iwire]

2. We did the load calc (started another argument when we did it) but we came in around 525 or 540a(can't remember now,but I will grab the project docs and check).

Is there a single 600 amp main with feeders to each panel or are there three service disconnects? (one in each panel)

 

[Gshock]

Is there a single 600 amp main with feeders to each panel or are there three service disconnects? (one in each panel)

Yup, 1 600a main with actually 4 feeders 3 apt panels 1 public.

 

[iwire]

Yup, 1 600a main with actually 4 feeders 3 apt panels 1 public.

Thanks.

 

[Gshock]

The real question would be how would you do it when the money is directly coming out of your pocket as a business owner?

How was it priced etc?

I have seen pictures of your work, it is outstanding and clearly you work in a segment that puts looks ahead of pricing. That is far from normal, at least in my experience.

If I was an EC I would not be quick to be generous with nice conduit with customer that nickle and dimed me on the original price which is generally what I see.

Gotta be honest I am just like this too. I like "pretty" work. which is why me and my partner argue all the time. He has the same argument, that I am always going extra to make jobs look nice and the customers almost never appreciate and NEVER pay for it. I can't help it though I like my work looking a certain way.

 

[iwire]

I can't help it though I like my work looking a certain way.

And truthfully when you are the business owner that should be entirely up to you.

However if you have a partner is that really fair to them?

Just talking here, and I have pretty much always been an employee so take my business advice for what it is worth.

 

[Gshock]

Thanks.

Panel disconnects are as follows 2x150a, 1x200a & 1x100a (public). I'm feeding them with 4/0, 2/0, and 1/0 SER respectively

 

[Gshock]

And truthfully when you are the business owner that should be entirely up to you.

However if you have a partner is that really fair to them?

Just talking here, and I have pretty much always been an employee so take my business advice for what it is worth.

Oh yeah, I agree with you. I fully respect my partner(he is the Sr guy in the tandem so I often lose to him anyway, which is way I am on here trying to get thoughts from others who he hasn't developed a prejudgement about). I like to think with my opulence and his practically we make for a great team .

 

[augie47]

You indicate there is a 600 amp main and a calculated load of 525 or 540.
(2) parallel 350 AL is out as that would only give you a 500 amp capacity, too small for your load and your main..
(3) 4/0 AL would give you your 540 amps (unless you placed them all in 1 conduit).