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Electrical outlets--daisy chain vs j-boxes

11883 Views 6 Replies 7 Participants Last post by  AllanJ
I want to add new outlets to my basement workshop. I'm planning two new 20 amp circuits of 6 receptacles each. The breaker box is at one end of the basement, the farthest wall is 50 feet away.

The joists in the ceiling are open. I don't want to run conduit horizontally along the walls to connect the outlets, because of all the obstructions along the way. I have holes already bored in the joists from prior wiring I can use to run the cable.

It seems the usual way to wire them is to daisy chain one outlet to the next using pigtails. This avoids the need for junction boxes, but it seems to me the total number of splices are the same. They are just moved from the j-box to the receptacle box.

My concern about daisy chaining is the possibility of voltage drop. A table from cerro wire suggests that, for 12g wire, 50' is the max distance of cable at 1500 watt loads. Since that is the distance of the farthest wall, does that mean that I should not daisy chain (which would add around 8-9 feet of cable per outlet branch, dropping from the joists and back up), but use only j-boxes?

The only issue then is that each receptacle would need to be gfci, since I couldn't use the first one in each circuit to protect the other outlets. Or then should use a gfci breaker.

Do I have this right?
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Non-issue. You are searching for a solution to a problem that does not exist.
50 ft of #12 in the home is but a nominal distance. A quick calculation shows less than 2% VD @ 15 amps @ 50 ft. Wire your receptacles any way you wish and sleep tight.

If you use a voltage drop calculator, make sure you insert the correct run length. AC length must be doubled (to and from), but many calculators automatically do it for you.
I have never been concerned with voltage drop in a branch circuit less than 100 feet.
Daisy chain (your term) is the way to go and is by far the normal method.
BTW, a 20 amp 120 volt circuit has the capacity of 2400 watts.
If it helps from a practical standpoint, I had this same dilemma when wiring outlets for a 1st floor home office recently. I ended up doing one wire per outlet and a central J-box in the basement. One thing this house always suffered from was a lack of flexibility when it came to wiring (think four original circuits for the entire 1950's dwelling) so I figured if my needs changed it would be much more flexible to add or switch around circuits using boxes. It is also much easier to wire as you don't need to mess around with pigtails. That's just my two cents and as always YMMV!
If your really worried about voltage drop ?
Simply use bigger cable,
For instance use 12# instead of 14#
But in most instances it is not a big issue.
Are you expecting any large loads
At the end of the line ?

If you want ground fault circuit interrupter protection, you can treat the first ceiling junction box as a pull box instead of a j-box.

The power feed wires come in and go down to the first outlet box to connect to the GFCI receptacle (line terminals). The continuing wires connected to the GFCI load terminals go back up to the j-box and over to the next j-box with splicing (wire nuts) for that outlet box and further continuation.
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