SER Romex same thing for ampacity? TW

[zcanyonboltz]

I know we use the 60c column for romex and conductors TW or UF from table 310.15(B)(16) 2014 NEC and when equipment terminals are rated 100A or less 14 AWG through 1 AWG
110.14 (C)(1)(a).
My question is two parts what does TW stand for? And, can SER cable be sized using the 75c column the gray SER cable I believe is marked XHHW, or is SER sized using the 60c column? Thanks

 

[Dennis Alwon]

My question is two parts what does TW stand for? And, can SER cable be sized using the 75c column the gray SER cable I believe is marked XHHW, or is SER sized using the 60c column? Thanks

TW-- thermoplastic and water resistant.

As far as the ser being used at 60C or 75C depends on what code cycle you are using and what is the conditions of the install

 

[infinity]

TW is an insulation type and being a 60 degree C conductor is can only be used at
its 60 degree ampacity regardless of size.

 

[zcanyonboltz]

TW-- thermoplastic and water resistant.

As far as the ser being used at 60C or 75C depends on what code cycle you are using and what is the conditions of the install

The NEC cycle is 2014 the terminations are rated over 100A. 4/0 Aluminum XHHW is rated to 150A in the 60c 180A in the 75c column and 205A in the 90c column.
Every company I have ever worked for pulls 4/0 to a 200A panel.

2/0 Aluminum is 115A 60c,135A 75c and 150A 90c. We always pull 2/0 to a 150 panel. This said we pulling wire based on the 90c column. The only reason I see that we do this legally is that the SER is XHHW-2 and all terminals are rated to 90c. What my hang up is that I was taught to always size romex to 60c.

So I guess my question is SER is NOT Romex right?

 

[luckylerado]

SER is NOT Romex right?

Right, however:

338.10(B)(4)(a)

(4) Installation Methods for Branch Circuits and Feeders.
(a) Interior Installations. In addition to the provisions of
this article, Type SE service-entrance cable used for interior
wiring shall comply with the installation requirements of Part II
of Article 334, excluding 334.80.
Where installed in thermal insulation the ampacity shall
be in accordance with the 60C (140F) conductor temperature
rating. The maximum conductor temperature rating shall be
permitted to be used for ampacity adjustment and correction
purposes, if the final derated ampacity does not exceed that for
a 60C (140F) rated conductor.

 

[electrofelon]

The NEC cycle is 2014 the terminations are rated over 100A. 4/0 Aluminum XHHW is rated to 150A in the 60c 180A in the 75c column and 205A in the 90c column.
Every company I have ever worked for pulls 4/0 to a 200A panel.

2/0 Aluminum is 115A 60c,135A 75c and 150A 90c. We always pull 2/0 to a 150 panel. This said we pulling wire based on the 90c column. The only reason I see that we do this legally is that the SER is XHHW-2 and all terminals are rated to 90c. What my hang up is that I was taught to always size romex to 60c.

So I guess my question is SER is NOT Romex right?

The "next size up rule" comes into play too which is why you see often see SER protected above its ampacity, or the "residential sizes" seemingly being used when it shouldnt. Under 2014, SER can be used at 75 degrees if not installed in thermal insulation.

 

[infinity]

2/0 Aluminum is 115A 60c,135A 75c and 150A 90c. We always pull 2/0 to a 150 panel. This said we pulling wire based on the 90c column. The only reason I see that we do this legally is that the SER is XHHW-2 and all terminals are rated to 90c. What my hang up is that I was taught to always size romex to 60c.

So I guess my question is SER is NOT Romex right?

"Romex" is type NM cable, SER is type SE cable. You can use NM at its 60 degree C ampacity only. For SE cable the maximum is at its 75 degree C ampacity. Neither cable type can be used at 90 degrees C.

 

[zcanyonboltz]

The "next size up rule" comes into play too which is why you see often see SER protected above its ampacity, or the "residential sizes" seemingly being used when it shouldnt. Under 2014, SER can be used at 75 degrees if not installed in thermal insulation.

Thanks for the replies the next size up makes sense.