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Old 07-18-2010, 06:19 AM   #1
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Must I wire "in parallel" in this case?


Was reading on series vs parallel and may have mis-wired a box yesterday. Situation: Power in from 20A breaker to receptacle. What I did: ran hots off of the second set of terminals than did a splice one going to nearby light switch and a second to another outlet whee it continues on in a series. If what is read is correct, since power goes to two different destinations, I'll need to pull the box and do the splices in what's called parallel fashion. I get the idea but lot o work so thought I'd check and make sure this is really required.
Thank you for any feedback.
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Old 07-18-2010, 07:11 AM   #2
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It's pretty hard to wire things in series with house wiring.
So, in your box you have 2 cables leaving going to two different devices down the line. You should have the two white wires wire-nutted together with a short pigtail that goes to the second silver screw on the the outlet. Same for the black wire but to the gold screw.
Is this what you have so far?

Last edited by a7ecorsair; 07-18-2010 at 07:15 AM.
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Old 07-18-2010, 07:17 AM   #3
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Not what I have. I came off the second set of terminals (hot and neutral) than spliced into two branches with wire nut. If receptacle failed both items downstream would die which is probably reason for rule (if there is such a rule) Trying not to have to go back in because local inspector requires every wire in box to have an extra 6 inches left in case somebody needs to work on it. Makes for a very crowded single gang box. A novice mistake. Would work fine but may not be code.

ALSO, it wouldn't be two white wires connected; it would be a four-way splice: (1) power in (2) hot, neutra,l ground to local receptacle (3) same to downstream light switch (4) same to next receptacle.
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Old 07-18-2010, 07:35 AM   #4
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Quote:
Originally Posted by Mi Feller View Post
I came off the second set of terminals (hot and neutral) than spliced into two branches with wire nut.
So you came off the second set of screws with a piece of romax. Where did you do the splice?
It is still in parallel not series. For the outlet to fail, the tie between the two screws would have to melt - not likely.
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Old 07-18-2010, 08:45 AM   #5
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Thanks. That's what I figured when I did it. If this be "series" than what in tarnation is a parallel? Also, long as I was able to mush everything back into the box, is it likely an inspector would still disallow it as being too crowded or am I worrying needlessly? (the hot in comes through crawl and numerous floor joists. would take hours to replace should I make any mistakes trying to cut out excess wire). Thanks for all.

Re: your question. All splices contained in single gang plastic box along with the wall receptacle. For ground, since they only give you 1 screw, I did a four way splice (one in and three out) one of which goes to the receptacle. For the hot and neutral, as you have surmised, I came off the second set of screws and did 3 way splices. From what you said it sounds OK. Only other possible issue is box is very crowed, but was able to tuck everything in safely. The power in would take hours to replace if I messed anything up, coming through a crawl space and numerous floor joists in the new addition. Leave well enough alone???
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Old 07-18-2010, 09:19 AM   #6
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Series and parallel can be somewhat confusing. Outlets, although physically seem to be in series - one after the other, they are electrically parallel - each outlet has the same voltage. If you have a string of outlets (parallel) with lamps plugged into each of them the current that flows through each light bulb does not pass through any other light bulbs. The sum of the currents flowing in each light bulb will add up to the current that is flowing out of the circuit beaker. You can unplug any lamp and the other still work.
A light switch is an example of a series circuit. The switch has only hot wires and is "in series" with the light fixture hot terminal. In other words, all the current in the series circuit has to flow through all the "in series" devices.
Christmas tree lights are typically "in series" and if one lamp burns out the whole string is dead.
Hope this helps...

Quote:
Originally Posted by Mi Feller View Post
Re: your question. All splices contained in single gang plastic box along with the wall receptacle. For ground, since they only give you 1 screw, I did a four way splice (one in and three out) one of which goes to the receptacle. For the hot and neutral, as you have surmised, I came off the second set of screws and did 3 way splices. From what you said it sounds OK. Only other possible issue is box is very crowed, but was able to tuck everything in safely. The power in would take hours to replace if I messed anything up, coming through a crawl space and numerous floor joists in the new addition. Leave well enough alone???
Here is where you can run into trouble with the inspector. Boxes have a cubic inch size and the size will determine how many wires, devices, and splices can be in the box. A standard 18 cu in box will not support 3 #12 romex and an outlet. Can you see the back inside of the box or do you know what cu in box you used and what size wire?
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Old 07-18-2010, 09:43 AM   #7
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Blue plastic box. 3.5" deep. 3.5" high 2.5" wide. I doubt you could see the back with the wires tucked in. Yes there's 1 12-2 in and 2 12-2 out. Are all inspectors that fussy? I could call him tomorrow before doing this or could end the agony right now and put in a deeper box I picked up this morning.

OOOPS. Went out to swap boxes and found the one I picked up this morning to be same size. Unlikely could go deeper; there's only half inch between back of box and end of wall stud. Unless you're talking about going wider on the box? A bit of a quandary here. The other side of wall is attached garage and could mount a junction box on the wall behind this if you think it's really necessary.

look alike box says 21" sq volume. (My math puts them at about 30 ???) Would 21 qualify for 3 romax and outlet?
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Old 07-18-2010, 10:44 AM   #8
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Here's how it's done
#12 wire counts as 2.25 and you have 6 = 13.50
A device (outlet) counts as 2 wires = 4.50
All grounds count as 1 conductor = 2.25
Pigtails don't count
This equals 20.25 cu in
If the box has wire clamps that you tighten with a screw then you have to add another 2.25
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Old 07-18-2010, 11:14 AM   #9
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Thanks A7 for the tutorial on parallell circuits and the handy volume chart. Have a good day. mif
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