Okay, I've got a 100 Amp panel which I have my garage on a 20 amp circuit. It has twinned up romex (12/2) running to it. (about a 100 ft. run) I seem to blow a breaker when I run to much at the same time on it. (of course I do, I know I know, that's what supposed to happen). Anyway, my question is, could I put in a 25 amp breaker or possibly a 30 and run that safely??
I have a compressor (15A), 8 flourescents (?), 2 1.5 amp chargers on all the time, garage door opener, bench grinder, stereo, and misc. hand tools on at intervals.
In order to keep your insurance valid, you have to follow the rules. The rules say #12 for GP/L (general purpose/lighting) at no more than 20 amps. (Actually very complicated rules, but all with a good reason, and the norm for professionals and the courts.) These things somehow survive a fire, and you risk all. You mention "twinned romex", what exactly does that mean?
What is meant from that is there are two pieces of romex joined together at the house panel and ran to the garage, then they are joined together at the garage 100 amp panel, and I installed the panel and breakers from there at the garage level. Was a little box before with one of those old fuses in it wrapped in metal to complete the circuit. (*cough* hacks)
I do however plan on updating the garage service cause I know this is not correct as it stands. But I need to wait while I have the trench open, to run everything else such as gas, water, cable and telephone. No sense in digging, running service, wait a few months, dig up again, and run water, wait a few..... You see the pattern. Unfortuneately, money only goes so far and meanwhile I"m blowing my breaker about once a day presently.
So since there's two pieces of newer Romex 12/2 run as the main power, could I safely run a 25 or 30 amp breaker for the garage? Or the same answer as before, (20 amp)??
By the way, I'm not the idiot that did this hobo wiring, just purchased this house about a season ago and fixing things as we go here.
There's something in the code book about running two sets of conductors in parallel to increase the ampacity; I'll look it up later. 25A or 30A breaker is probably OK. BUT...
since you gotta buy a new breaker anyway, why not get one of those tandem
1/2-width breakers that let you put two 20A circuits in one space (and on the same phase!) in your service panel? Put one black wire from your paired cables on one half of the breaker, and the other black wire on the other. AGAIN, THEY MUST BE THE SAME PHASE. Don't use a normal 2-pole breaker. Then to keep everything kosher, tie the handles together (there should be a little hole in the handle to do this).
The way it is now is not code, but it sounds safe, since a single 12/2 is rated at 20 amps. NEC does not permit "twinned" wires smaller than 1/0. The problem with a bigger breaker is that if one of the wires opens up for any reason, the other is over capacity and you have a potential fire on your hands.
Another consideration: The second wire may have been added to deal with the voltage drop, which is about 6% on a single 12/2 run @105 feet. Raising the amperage will increase the drop.
You better get down to the city hall and talk to a building inspector about what's legal and why. Digging one trench and running multiple services all together is verboten in many places, and hazardous in all of them. Of course if you have a six foot wide trench it may not be a problem. Check it out for your own safety. Good luck.
OK, I looked it up. The code doesn't allow parallel conductors that small; when you do have parallel conductors, the overcurrent protection has to be small enough to protect one wire if the other wire fails.
Putting each wire on its own 20A breaker and tieing the handles is the closest you can get to doing it right with the existing wires.
How deep are you planning on burying everything eventually?
Gas is definately a no-no, but most building departments would have no problem with electrical and telephone/catv in the same trench, as long as one or the other was in conduit.
Well, I gotta buddie of mine that is pretty good with this kind of stuff but really didn't want to ask him.(He's a Journymen) He's the one that helped with all the electrical so far and he won't touch anything unless its perfectly by code and I hear him whine and moan for a month if I do something not code myself. Which is very good I know but I was looking for a temporary fix that would be safe.
I believe he said the electrical has to be 3 feet down, the gas needs to be spaced I think 3 feet apart from other services and 3 feet down and everything else can be 2 feet down with that utility cation tape at 1 foot or so.
Idealy, I would like to run two conduits at at 3 feet down and run all my lines through these (low voltage lines in one, service in the other) in order to leave accessability open for future runs such as CAT5. What do you think about running all lines through a conduit? Waste of money or good idea?
Again, thanx again thus far for all the comments, help and time,
The depth depends on wiring methods and cover. In most cases, UF would be 24 in. down, PVC 18 in., GFCI single circuit 12 in. The main costs ( and/or labor) is in the trench itself, so use the PCV and over size the pipe for the next guy's welder, run the wire size you need, it won't be much of a cost difference. You will need a wet rated wire, the pipe will fill up with water.
I just thought of something else -- use a 2-pole breaker and change the existing wire to a 220V circuit. Use the black wire from one cable to feed one side of the hot bus in your 100A panel (a main lug panel, right?) and the other black wire to feed the other hot phase. Connect both white wires to the neutral bus, and both green wires to the ground bus. I don't think you get to bond the ground and neutral if you are going to also run water, telephone, or gas service between the two buildings.
Then divide your loads among the two phases in the box, and if possible rewire your air compressor for 220V.
When things like this come up (and considering my general aversion to things that make me tingle) I do one thing only. Find the bar where the electricians hang out and spend wisely.
[In other words, paralleling conductors is ONLY useful to reduce voltage drop. It doesn't really serve to increase the ampacity of the circuit.]
And not even that, under most circumstances.
Our codes prohibit "assembling a circuit" out of conductors that aren't in the same cable (or conduit or raceway). I suspect the NEC will say the same.
[In other words, paralleling conductors is ONLY useful to reduce voltage drop. It doesn't really serve to increase the ampacity of the circuit.]
And not even that, under most circumstances.
Our codes prohibit "assembling a circuit" out of conductors that aren't in the same cable (or conduit or raceway). I suspect the NEC will say the same.
There are two choices here:
1) Make the two sets of 12ga into two separate and independent 120V circuits. Doesn't give you 240V. Gives you two 20A 120V circuits.
2) Make one of the 12ga cable sets into a 240V circuit, and leave one as
120V. Gives you one 20A 120V circuit, and one 20A 240V circuit.
HomeOwnersHub website is not affiliated with any of the manufacturers or service providers discussed here.
All logos and trade names are the property of their respective owners.