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I had my electrical panel updated by a pro a few years back and this wire was on a 50amp breaker. When he updated the panel, he changed it to a 30amp breaker.

The wiring is aluminum and is from the 70s. It's currently used to power an electric stovetop. I wanted to use it to power an electric range/oven combo and swap it to a 40amo breaker if I can.

Unfortunately I can't find any identifying marks that helped me to understand what gauge wire this was other than the part that said "cors 8 AL" leads me to believe it's 8 gauge.

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  • If the new stove requires neutral, you might need to change that cable. These days a hot, hot, neutral circuit is frown upon, and were banned in new construction in 96 for being unsafe. That gauge also seems to be too small for 40 amps, but need better people to say for sure in that cable type.
    – crip659
    Oct 18, 2023 at 15:04
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    This answer has relevant information for a similar (not identical) cable. Yours is interesting, First glance I thought it was shielded, but of course not .. maybe it's meant to use the neutral as armor? But why? I'd mainly go with the thought that if you're touching this now you should replace it with a 4-conductor cable, and also that the amperage of the cable would be in documentation that is no longer available and was written before current standards were imposed.
    – jay613
    Oct 18, 2023 at 15:09
  • @FreeMan OP's electrician did change the 50 breaker to a 30 amp breaker.
    – crip659
    Oct 18, 2023 at 15:12
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    point finally sunk in @manassehkatz-Moving2Codidact. Comments deleted.
    – FreeMan
    Oct 18, 2023 at 16:46
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    If you wanted an answer not based on the (frankly, quite clear) CDRS 8 AL the end-on picture would need a ruler in it, at the same plane as the cut end, both in focus.
    – Ecnerwal
    Oct 18, 2023 at 16:58

1 Answer 1

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The markings Type SE Style U, commonly referred to as SEU cable, is a service entrance nonmetallic cable (similar to the nonmetallic cables we call "Romex" but larger gauge). SEU is commonly used to feed panels or large appliances.

The markings CDRS 3 8 AL mark it out as a 3 conductor cable of 8 AWG, made from aluminum.

SEU cable has two insulated conductors and one uninsulated concentric "shield/wrap" conductor which was commonly used as a neutral in old 240/120V circuits (something we now know to be incorrect). That stopped in the 1990s. You can still legally use the 3rd conductor as a ground, though.

By the NEC, It is not suitable to carry 40A. If you need a 40A circuit, you'd need 6 AWG AL (or 8 AWG Copper). Additionally, that is only a 3 conductor cable, so you'd only be able to run a 240V circuit, not a 240/120V as commonly used by a range.

There's no reason to remove it, though, even if you have to install another cable for your range circuit. This #8 SEU would be great to install a NEMA 6-30 on the end and call it a dedicated EV charging circuit. Even if you don't or won't have an EV, your listing agent will love it when you go to sell the house.

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  • Thank you for your thorough answer. Do you have a guess as to why this used to be on a 50amp breaker? I will run new 8awg wire to this location. Oct 18, 2023 at 15:26
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    Your electrician swapped it to 30A, which was a really good thing. Why was it 50A before? My best guess is: 40A and 50A use the same receptacle type, combined with someone getting confused (or simply didn't know, or was trying to cheat - no way to tell) and thought that since a 40A circuit was OK on 8 AWG Aluminum (it is OK) and that a 50A receptacle is what is physically installed in such situations (which is also correct) that the circuit actually changes to become a 50A circuit with a 50A breaker (which is absolutely wrong). An easy progression that can result in a disaster. Oct 18, 2023 at 16:07
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    @bigmike7801 If you're running new cable, the 6 AWG aluminum option is far more cost effective. And not inferior, despite a bunch of half-fast propaganda based on half-truths. Torque all the connections properly, with a torque driver, following manufacturer's specifications (whether using aluminum or copper that is a code requirement. It also was the major issue with old aluminum branch wiring, with a few other contributing factors that never applied to large circuits like this one.)
    – Ecnerwal
    Oct 18, 2023 at 16:17
  • “Half-fast”? What?
    – nobody
    Oct 18, 2023 at 20:57
  • @nobody - I'd guess that "half-fast" was typed instead of "half-a__ed" (fill in the blank with a double-s). Perhaps it was intentional obfuscation since if you pronounce it relatively quickly, they pretty much sound the same. Oct 19, 2023 at 8:10

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