ECN Electrical Forum - Discussion Forums for Electricians, Inspectors and Related Professionals
ECN Shout Chat
ShoutChat
Recent Posts
RV Forums
by BigB - 08/07/22 01:47 PM
NEC- 314.23 (H) (1)
by gfretwell - 08/07/22 01:07 PM
Wiring method choice
by gfretwell - 08/07/22 01:29 AM
Back From Retirement
by Bill Addiss - 08/05/22 07:39 PM
Load Calcs for EVs and RVs
by renosteinke - 08/04/22 07:34 PM
New in the Gallery:
240/208 to a house
240/208 to a house
by wa2ise, October 9
Now you know.
Now you know.
by Tom_Horne, September 7
Who's Online Now
0 members (), 26 guests, and 13 robots.
Key: Admin, Global Mod, Mod
Previous Thread
Next Thread
Print Thread
Rate Thread
Joined: Mar 2004
Posts: 16
J
JG Offline OP
Member
I recently saw a job with 4/0 al sevice single phase entrance conductors feed a 320 amp service, two 200 amp panels, a load calc of 228 amps. The engineer gave me a cut sheet listing the 4/0 at 315 amps, buried @90 deg C. Does this override 310.15 if 90 deg terminals are used?

Stay up to Code with the Latest NEC:


2020 NEC & Related Reference & Study Guides
2020 NEC & Related Reference & Study Guides
Pass Your Exam the FIRST TIME with these Exam Prep Combos:
 

>> Master Electrician Exam Prep     >> JourneyMan Electrician Exam Prep
 

Joined: Feb 2002
Posts: 182
B
Bob Offline
Member
You are required to use table 310.16 for NEC installations unless you want to invoke
310.60D Engineering Supervision. I am not sure what you are considering terminations but if it the compression connectors that not
correct. The terminals are for the meter socket and any other connectors involved. Ratings per 316.16 for 4/0 AL is 180 amps.

Joined: Jan 2004
Posts: 1,507
G
Member
I have no idea how he came up with 315a. If I understand the question, you are talking about a Service lateral sized at 4/0. This is figured differently than an electrician would size Service Entrance conductors. The Utility company have a different rating system based on established demands.


George Little
Joined: Mar 2004
Posts: 16
J
JG Offline OP
Member
You are correct GL, it is a lateral, only customer owned. I was under the impression 310.15 must be adhered to, when not installed by the utility. Please correct if misguided.
Thanks

Joined: Jan 2003
Posts: 4,391
I
Moderator
JG are you asking about Table 310.15?

You may use that table in some applications you never have to use that table.

If this service lateral is customer owned and covered by the NEC the choices are Table 310.16 which would allow 180 amps per 4/0 AL or as option you could use Table 310.15 which would allow the 4/0 AL to run a 200 amp service.

Any chance you have two sets of 4/0 AL?

Any chance the 4/0 was copper not aluminum?

It is worth noting that the service conductors feeding two or more disconnects do not have to be rated as high as the total overcurrent protection.

Service conductors feeding two or more disconnects only have to be rated to handle the load.

With a load calc of 228 amps 4/0 AL is out of the question.

4/0 copper would do it with a rating 230 with a calculated load of 228. [Linked Image]

Bob


Bob Badger
Construction & Maintenance Electrician
Massachusetts
Joined: Dec 2000
Posts: 4,289
Member
We have a couple of local utilities that have us supply and install the service lateral conductors. The are sized and specd by the PoCo's engineering.

Joined: Feb 2002
Posts: 182
B
Bob Offline
Member
"We have a couple of local utilities that have us supply and install the service lateral conductors. The are sized and specd by the PoCo's engineering."
electure
When you do this does it become the property of the utiltiy?

Joined: Dec 2000
Posts: 4,289
Member
Yes, it does. Is it different elsewhere?

Joined: Feb 2002
Posts: 182
B
Bob Offline
Member
electure
You are acting as a contractor for the utility. Since the NEC does not cover installations that are part of the distribution, they do not follow the same rules that the NEC applies to other installations. They caculate the load differently than required by section 220.
They estimate the load that will occur any give n moment and size the conductor to match this estimated load. That is why they can use 4/0 AL. In this case the conductor belongs to the home owner and it should be installed according the the NEC. In my opinion 4/0 is not large enough for this load.


Link Copied to Clipboard
Featured:

Tools for Electricians
Tools for Electricians
 

* * * * * * *

2020 Master Electrician Exam Preparation Combos
2020 NEC Electrician
Exam Prep Combos:
Master / Journeyman

 

Member Spotlight
Vlado
Vlado
Croatia
Posts: 28
Joined: February 2011
Top Posters(30 Days)
BigB 5
Popular Topics(Views)
294,645 Are you busy
226,409 Re: Forum
211,644 Need opinion
Powered by UBB.threads™ PHP Forum Software 7.7.5