The first, and most obvious, thing that we need to state is: unless you are 100% confident with handling electrics then under no circumstances should you interfere with wires and amps yourself… speak to a licensed electrician who can help you with this.
Electricity is not something that you can just fluke and then get away with it.
Now, on to answering the question: can 12 gauge wire handle 30 amps? Well, this is one of those straightforward yes or no questions where there is no room for negotiation or leveridge. We have one word for you:
And by no means should you attempt to bend this or cut corners in any way, be it a slight adjustment.
As far as electrics are concerned, no means that by absolutely no means at all should you do this. This will pose major health and safety risks, so we are here to give you the official red flag on this one.
However, there are wires out there that are designed especially for handling 30 amps - so you are not completely at a loss. You might just have to make another purchase, but for the sake of avoiding a pretty serious malfunction this is worth the investment.
How Many Amps Can 12 Gauge Wire Handle At 240 volts?
Well, you should only use 12 gauge wire for a 20 amp circuit, so although this does not seem all that far off 30 - the wire will not be able to cope with the amperage.
Additionally, this goes on to other gauge wires. For instance, 10 gauge for a 30 amp circuit, 8 gauge for a 40 amp circuit, 6 gauge for a 50 amp circuit and so on.
The conclusion here is pretty straightforward: clearly, 12 gauge wire cannot handle 30 amps. Why is this?
We can confirm that this is because you need a minimum of 10 AWG for 30 amps. It is important to note that electrical current is measured in amperage, and each wire gauge has a maximum safe carrying capacity.
There are a range of gauge wires out there depending on the amperage you are using. And, the values given are by no means a minimum - they are the absolute maximum. So, for standard non-metallic (NM) cables, these amperage capacities are:
- 14-gauge wire - 15 amps
- 12-gauge wire - 20 amps
- 10-gauge wire - 30 amps
- 8-gauge wire - 40 amps
- 6-gauge wire - 55 amps
- 4-gauge wire - 70 amps
- 3-gauge wire - 85 amps
- 2-gauge wire - 95 amps
This list is referring to the amperage capacity or “ampacity” of the conductor (wire) and is often correct.
Sometimes, these general rules lead technicians to believe that if an appliance is rated for 50-amp breaker or fuse maximum overcurrent circuit protector (MOCP), you must use 6-gauge wire and a 50-amp circuit breaker.
It’s not that simple according to the National Electrical Code (NEC) NFPA 70 for several reasons. Here are some additional factors to be considered:
- What the conductor is made of - so, is the conductor made of aluminum, or is it made of copper, or is it made of something else entirely?
- What the ambient rating of the conductor is - the wire and additionally its termination points need to be considered.
- The type of load that is being controlled - what you are trying to power.
- What the other thermal de-rating conditions that exist are - this poses the question as to whether there are multiple conductors in a raceway and high ambient conditions.
- What the allowable voltage drop based on wire length is - just to be clear, this is not dictated by the NEC but rather by the requirements of the connected load.
Just to reiterate, unless you are totally confident with electrics and know what you are doing, then you need a licensed electrician.
Messing with electricity is really dangerous if you do not know what you are doing, so get a professional in to do it properly.
In fact, in many jurisdictions even a Do-It-Yourself homeowner must use a licensed electrician for electrical works.
If there is a problem, and it results in damage (for instance, the worst case scenario would be your house burning down) and the insurance company finds that you did the work and didn’t have it properly inspected, any claim you make to your insurance company may be denied.
What Gauge Wire Should I Use?
Well, it is recommended that you should use a 10 gauge wire to handle 30 amps.
NEC 10-gauge copper wire has a rating of 30 amps. 10-gauge solid copper wire in general has a resistance of almost exactly 1 ohm per 1000 feet.
The rating is limited by how much heat the insulation was designed to withstand. NEC 60/75/90 deg C rated insulated wire is rated for 30/35/40 amps respectfully.
What Size Wire Do I Need For 30 Amps?
Any circuit fused for 30 amps must use a minimum of 10 ga copper or 8 ga aluminium, and additionally, longer runs may require an upgrade of wire size - so it is all pretty situational.
Can 10 Gauge Wire Handle 35 Amps?
Well, there are no 35 amp breakers that we are aware of. You would normally use 10 on a 30 amp breaker running at 80% and so 24 amps would be the capacity in use.
Additionally, on a 40 amp breaker it would be 32A and with the right insulation you may be able to get away with it.
The Final Points
So, to bring you back to the original question that we started out with: can 12 gauge wire handle 30 amps? The answer is a resounding NO, but we have given you alternative wire options and important points to consider when dealing with electricity.
And remember, if you are not all that sure on what you are doing then get a licensed electrician to help you out. There really is no shame in not wanting to electrocute yourself.