So an outlet on my 20 amp circuit exploded or something there was a big flash and sparks and the walls are black around the outlet. I had been using this outlet at near capacity for some time but when it exploded it was only powering one 2ft 4bulb t5 fixture. I believe the outlet is fairly old and perhaps was taxed and on its last leg because this happened using only roughly 100W. The wires weren't melted or anything and I can tell it happened in the outlet because the top outlet is completely toasted. Should I be able to replace this old outlet and be fine? Again no idea how old it was it was in the house when I moved in. In hindsight I should have replaced it with a brand new outlet considering the load it was going to be carrying. It powered my veg tent which ran 24/7 so I think this might have been a factor.

The breaker has worked correctly in the past for overload situations but I've read sometimes old outlets can suffer from metal fatigue and the contacts can loosen within the outlet and cause a short.

Was the outlet also 20 amp or was it a 15 amp outlet? The outlet will have its own rating, independent of what the circuit is.

Odds are you're correct about your outlet. If you feel comfortable with it ,shut off breaker and replace outlet, only 2-3 bucks.

Quote: ross wrote in post #3

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The breaker has worked correctly in the past for overload situations but I've read sometimes old outlets can suffer from metal fatigue and the contacts can loosen within the outlet and cause a short.

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I suspect that the outlet was a 15 amp also, but I don't see how a T5 could be too much amperage. I have my T5 and a small space heater on a 15 amp circuit for my vegging room and never have any problems with that circuit.

Doesn't everyone put a GFI in their growrooms? Especially when you have run a dedicated circuit. I had a dedicated circuit run, but have about 6 outlets run off it so no one outlet is too taxed.

It's the outlet for the washer so it's dedicated but unfortunately only one plug. It wasn't the type of outlet where you wrap the wires around the screws on the outside but rather possibly an older style I've never seen where the wire plug into holes in the back of the outlet. It was only a 15amp outlet. Unfortunately I never thought to check.

Also THG should I get a 20 amp GFI? I've installed gfis before but it's been a while I'm assuming you go about it just like a normal outlet?

How can I tell the gauge without seeing the wire casing? I can't pull any slack thru the wall to see

If your concerns are over whether to get a 15 or 20 amp rated outlet assuming this is why you're trying to find wire gauge size. #14=15 amp and #12=20 amp max load you can't go wrong in buying a 20 amp rated outlet, you can put a 20 amp rated outlet on a #14 gauge/15 amp circuit but should not put a rated 15amp outlet on a 20 amp circuit. The 20 amp outlet does give more plug configuration options. You usually wont find #14/15 amp circuit in homes anymore, older places yes. I've seen it many times, no matter where you go there are 15 amp outlets on 20 amp circuits, in 30 years in this field I've never seen a problem with a 15 amp outlet on a 20 amp circuit. If you need to follow the letter of the law on this one the NEC says it is a no-no. Wiring outlet goes "black on brass , white on silver and green on green ground screw. Brass and silver are simply the screw colors where the wires attach to the outlet. I hope this helps.

It seems fairly stiff. I cut off a one inch piece and it's very hard to bend with my fingers. The wiring has carried probably close to 2000W for close to 2 years now (not constantly) and is fine apart from the tips that were in the outlet explosion. I've read that this can happen when there is no load at all if the metal on the inside falls apart and causes a short. Kinds weird tho since this is the first week in maybe a year it wasn't powering at least 400w. Now that I see myself type that it's sounding like metal fatigue is a real possibility considering the outlet seems old.

Thanks twinken. It indeed was a 15amp outlet on a 20amp. And it ran over 15 amp 12 hours a day. I think the issue was in the outlet not the wiring.

it is not recommended to exceed 80% of a circuits max amperage. i wouldnt use more than 15 amps on a 20 amp.

Repalce the outlet with a 20 amp CFI. Is your wiring copper,hope so?The old type Aluminum wiring gets loose easy and will spark and start fires.

WH do you mean GFI?

Yep,,Sorry,,couldnt edit. LOL

Got the gfi in. At first it was tripping each time I plugged in the power strip with my 400w and a couple fans on it but then I got it to stay on and now it seems to be good. Hmm....

Humm,,wounder why it was tripping? That aint good Bro.

I don't use them in my grow room because I don't have any water in my grow room but you could try plugging your biggest load first then the rest. The GFCI can sense a very small amount of current change. This may explain it better.

Zitat

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That outlet is called a ground-fault circuit interrupter (GFCI). It's there to protect people from electrical shock, so it is completely different from a fuse.

The question on appliance plugs talks about fuses. The idea behind a fuse is to protect a house from an electrical fire. If the hot wire were to accidentally touch the neutral wire for some reason (say, because a mouse chews through the insulation, or someone drives a­ nail through the wire while hanging a picture, or the vacuum cleaner sucks up an outlet cord and cuts it), an incredible amount of current will flow through the circuit and start heating it up like one of the coils in a toaster. The fuse heats up faster than the wire and burns out before the wire can start a fire.

A GFCI is much more subtle. When you look at a normal 120-volt outlet in the United States, there are two vertical slots and then a round hole centered below them. The left slot is slightly larger than the right. The left slot is called "neutral," the right slot is called "hot" and the hole below them is called "ground." If an appliance is working properly, all electricity that the appliance uses will flow from hot to neutral. A GFCI monitors the amount of current flowing from hot to neutral. If there is any imbalance, it trips the circuit. It is able to sense a mismatch as small as 4 or 5 milliamps, and it can react as quickly as one-thirtieth of a second.

So let's say you are outside with your power drill and it is raining. You are standing on the ground, and since the drill is wet there is a path from the hot wire inside the drill through you to ground (see How Power Distribution Grids Work for details on grounding). If electricity flows from hot to ground through you, it could be fatal. The GFCI can sense the current flowing through you because not all of the current is flowing from hot to neutral as it expects -- some of it is flowing through you to ground. As soon as the GFCI senses that, it trips the circuit and cuts off the electricity.

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Not sure it couldn't have been the load it was 500w max. It's been going fine for a few hrs and I turned the timer on and off to simulate that and see if it was maybe the surge that did it but it didn't trip