50 amp breaker on #8 ok?

19 years ago

Hi,

It's my understanding that a 40W breaker should be used with #8 wire. The cooktop specs call for a 50 amp breaker (it doesn't specify wire type or size). The contractor ran ~60' of 8/3 copper-stranded wire. Can a 50 amp breaker be safely used or do we need to step down to a 40 amp breaker and face the possiblility of tripping the breaker when using the cooktop at full capacity? Or, would a third option require yanking the #8 and replacing with #6? Also, does stranded vs. solid copper affect its amperage-load? Thanks.

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Comments (5)

spencer_electrician
19 years ago
No not safe to use a 50 amp breaker. The only time a 50 amp would be ok with #8 woul be if these were individual thhn wires in conduit. You need a 40 amp breaker. If the stove specifically calls for a 50 amp breaker the wire does need to be replaced in order to use a 50 amp breaker. That also is $140 worth of wire but if the contractor did this, he should of sized it to the oven you specified and he has to fix it. Some on here argued before to go ahead and use a 40 amp breaker because the stove only ends up using under 40 amps but after weeks of discusion the decision was you must follow the manufacture's instructions which called for a 50 amp breaker in that case.
bigbird_1
19 years ago
If you need a 50A breaker, then you also need 6/3 wire. Stranded vs solid does not affect the current rating of the wire. It only affects the ease of bending/working the wire.
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solarpowered
19 years ago
Now wait a minute, what exactly did the contractor run? If he ran #8 NM cable, then, yes, you have a problem. If he ran #8 of practically anything else (say, AC or MC cable, or individual wires in any kind of conduit), then you're good to go at 50 amps.
kangaroo
Original Author
19 years ago
Thank you all for responding and confirming my concern that there was a problem with the installation. The wire is NM type and I'm pretty sure it's #8. The reason I'm not 100% sure is that the info on the wire is stamped as opposed to printed and at each repeating point where the gauge is indicated it is barely legible. Rubbing a pencil on it pretty much confirmed that it reads "8/3". The cable itself is no more than 5/8" in diameter and is pretty flexible.

Is there an online code resource I can access which will document the requirement for #6 gauge with a 50 amp breaker?
PRO
Avery Construction
6 years ago
last modified: 6 years ago
Wow, I know this is an old post, but seriously? Is anyone replying actually qualified? So the fact it's nm (solid) is the only reason it shouldn't be installed for 50a. Is the run actually 50' or 30' of a 50' roll? Distance makes a difference. But stranded does make a difference. If he ran se (stranded) ie xhhw it is just fine.

Example 2 to prove it absolutely makes a difference