service cable

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smoke stack lightning

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Good sirs, the plan is to upgrade the dwelling to 200A. From the main disconnect at the meter I want to pipe up to the attic and run accross the entire attic to the garage (where the panel is) with 4w SCR aluminum cable.

The question is , where in the code are the adjustiment tables for excessive ambiant heat for SCR cables? Is it safe to say that the insulation is XHHW and it gets treated as such in table 310.16? Or is a special condition because of its multi-conductor assembly?

Thanks for your time
 
radiopet

radiopet

Senior Member
Location
Spotsylvania, VA
I believe you are asking about "SER" right....sorry as I am not sure what SCR is or maybe I just dont use that term. The "Correction Factors" are below T310.16.
 
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smoke stack lightning

Member
Sorry for not being clear. Its just a 4 wire qualplex aluminum cable wraped in gray sheathing usually used to feed sub-panels. I know it as SCR because its round unlike SCU witch is flat. I guess its just regional slang.
 
480sparky

480sparky

Senior Member
Location
Iowegia
smoke stack lightning said:
Sorry for not being clear. Its just a 4 wire qualplex aluminum cable wraped in gray sheathing usually used to feed sub-panels. I know it as SCR because its round unlike SCU witch is flat. I guess its just regional slang.
Click to expand...

Dis stuff?

SERcable.jpg
 
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Cow

Senior Member
Location
Eastern Oregon
Occupation
Electrician
It's not regional slang, you're misspelling the abbreviations. SER and SEU are the correct terms. Those....you will find in the code book.
 
infinity

infinity

Moderator
Staff member
Location
New Jersey
Occupation
Journeyman Electrician
Table 310.16 is for conductors in raceways or cables so the adjustment factors at the bottom of the table apply to SER in an attic. Since you have XHHW which is rated for 90 degrees you can use the adjustment factor in the 90 degree column at the bottom.
 
busman

busman

Senior Member
Location
Northern Virginia
Occupation
Master Electrician / Electrical Engineer
SCR is probably slang for ACSR which is Aluminum Cable, Steel Reinforced. This is a cable where most of the strands are aluminum for conductivity and one (or more) are steel for tensile strength. It's used for long overhead spans. Also a really good way to destroy a set of cutters.

Mark


 
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hillbilly

Senior Member
Just curious.

How many of the residential sparkies on this site derate SER for temperature in attic spaces?:)

steve
 
augie47

augie47

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Location
Tennessee
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State Electrical Inspector (Retired)
hillbilly said:
Just curious.

How many of the residential sparkies on this site derate SER for temperature in attic spaces?:)

steve
Click to expand...

doesn't 338.10/334.80 somewhat take care of that for you. If you take an attic temperature of 130?F and apply the dreating to the 90?C rating you pretty much end up at the required 60?C rating.
My understanding was that was the primary point behind the 60? requirement.
 
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hillbilly

Senior Member
augie47 said:
doesn't 338.10/334.80 somewhat take care of that for you. If you take an attic temperature of 130?F and apply the dreating to the 90?C rating you pretty much end up at the required 60?C rating.
My understanding was that was the primary point behind the 60? requirement.
Click to expand...

I agree.
I guess my point (if I have one) is what to do about ambient temperature verses derating verses Table 310.15(B)(6).:roll:
The cable is already de-rated for ampacity by the table, and Article 310.15(B)(6) makes no mention of temperature adjustment for ampacity.
Do you de-rate a cable that's already been derated?

Making any sense?:)

steve
 
augie47

augie47

Moderator
Staff member
Location
Tennessee
Occupation
State Electrical Inspector (Retired)
My answer would be yes and no :grin:
If a conductor is derated for something other than ambient, such as fill, the you would still have to derate for ambient, however (the "no"), if you look at 334.80 it states that the 90? column can be used for derating.
It appears to me that for NM (and interior SE) the Code has already taken care of the ambient derating by the restrictions.
 
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