100a or 90 OCP on AL2-2-2 SER

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mikeames

mikeames

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I believe this has been discussed in the past.

AL 2-2-2 ser should have a max of a 90 amp OCP correct?

I use to use 100A and still dont see a problem with it but Have since changed to save the possible aggrvation and time later when it dosent pass inspection. I continue to see others do it both ways. So whats the correct OCP???
 
Re: 100a or 90 OCP on AL2-2-2 SER

However, feed a sub-panel or other load, and the 90a rating applies.
 
Re: 100a or 90 OCP on AL2-2-2 SER

I don't have my code book in front of me. However, last I recall NM, UF, SE all had to be based on the 60 degree table.

The use of #2AL at 100amps was only for service entrance/feeders on one and two family dwellings.
 
Re: 100a or 90 OCP on AL2-2-2 SER

I don't have my code book in front of me. However, last I recall NM, UF, SE all had to be based on the 60 degree table.
Click to expand...
Where does it say that SE must be rated at 60 degrees?
 
Re: 100a or 90 OCP on AL2-2-2 SER

This is a good example of using the UL White book to help alleviate some of the confusion.
SE Cable is typically manufacturered with RHW or XHHW Type conductor insulation. Both are rated for 75degree C column, and if there is a -2 after the insulation Type, it is rated for the 90degree C column.
 
Re: 100a or 90 OCP on AL2-2-2 SER

as Scott states, the correct answer is somewhat dependant on whats being fed.
In our area 2 AL SE is a 90 amp cable based on 75o col.310-16 UNLESS the load meets the criteria
of 310-16(B)6 (MAIN POWER feeder or service conductor/3 wire 1o residential)
 
Re: 100a or 90 OCP on AL2-2-2 SER

I could have been more clear. In my area we use 310.15(B)(6) for any feeder, even to a sub-panel. (One and two family of course, this is assumed)

IMO the wording in this section is somewhat vague, but it specifically implies, for this section, that a main power feeder is any feeder between the main disconnect and lighting and appliance panelboard(s).
"Main" does not specifically have to be just the feeder TO the main disconnect.
 
Re: 100a or 90 OCP on AL2-2-2 SER

A couple of comments:
Article 110.14(C)(1) limits ALL conductors #1 and smaller to the 60 degree C column UNLESS you KNOW that all terminations are rated for a higher temperature.
310.15(B)(6) gives the ampacity of certain conductor types (SER is not specifically listed so you will need to determine what kind of conductor your cable includes)when used for dwelling services or FEEDERS.
If the conductor type is suitable then you may use the ampacity from table 310.15(B)(6) for this as long as it is a dwelling feeder, but not if it is a branch circuit.
 
Re: 100a or 90 OCP on AL2-2-2 SER

It seems as using this table for feeding sub-panels would be a violation. 310.15(b)(6) would only apply to service-entrance conductors, service lateral conductors, and feeder conductors that serve as the main power feeder to a dwelling unit. Seems as though using this table to size conductors to a sub-panel within a building or feed an outbuilding would be a violation. You would need to use 310.16 for this.
Load diversity being the reasoning to my understanding.

[ December 14, 2005, 10:07 AM: Message edited by: BruceH ]
 
Re: 100a or 90 OCP on AL2-2-2 SER

So then the final answer would be 90A in most cases.

I cant remember the insulation type is it usually

XHHWN
???
 
Re: 100a or 90 OCP on AL2-2-2 SER

Originally posted by mtn_elec:
sorry Larry, but, where you get the 90 Amps from?
Click to expand...
It would be a branch circuit. Feeding a remote panel "Sub Panel"
 
Re: 100a or 90 OCP on AL2-2-2 SER

Look at 310.15(B)(6) again. Cable type SE is specifically listed in the table, as is USE.

The definition of "main power feeder to a dwelling" may not be what you think. A literal reading of the definition (to me) implies that it can feed other lighting and appliance panels connected to the main disconnect panel. But we don't need to start that debate again.

If you want to use 310.15(B)(6) to feed a sub panel, better check with your inspector as it seems the answer as to whether it applies varies considerarably.
 
Re: 100a or 90 OCP on AL2-2-2 SER

2005 cycle
310.15(B)(6) 120/240-Volt, 3-Wire, Single-Phase Dwelling Services and Feeders. For individual dwelling units of one family, two-family, and multifamily dwellings, conductors, as listed in Table 310.15(B)(6), shall be permitted as 120/240-volt, 3-wire, single-phase service-entrance conductors, service lateral conductors, and feeder conductors that serve as the main power feeder to each dwelling unit and are installed in raceway or cable with or without an equipment grounding conductor. For application of this section, the main power feeder shall be the feeder(s) between the main disconnect and the lighting and appliance branch-circuit panelboards(s).


338.10 (B) Branch Circuits or Feeders.
(1) Grounded Conductor Insulated. Type SE service-entrance cables shall be permitted in wiring systems where all of the circuit conductors of the cable are of the rubber-covered or thermoplastic type.
Click to expand...
To use the table in 310.15 the feeders are required to be between the main disconnect and the panel board such as found in a mobile home.

338 tells us that the SER (four conductor) cable is the same as SE cable. The ?R? only means that the grounded conductor of SE cable is insulated.
:)
 
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