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# Challenging box fill calculation

## Challenging box fill calculation

#1
04-08-17, 06:24 AM
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Challenging box fill calculation

More remodeling - need to clean up this mess for the attic fan. We replaced the sheetrock where these had been punched in w no wires attached to studs. The boxes are undersized so I's like to get everything in one mounted box.

There are two switches, a fan timer and a Hi-Off-Lo.

I don't know how to calculate for the wires that would be internal in one box. There are six from the Hi-Off-Lo switch and the one 14-3 NM-b (black sheathing) would become an internal connection.

Thanks guys.

#2
04-08-17, 07:11 AM
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Pigtails or wires that are part of the switch do not count towards box fill. You count the conductors in the cables towards fill.

All grounds count as one as well as any internal clamps. Any device will count as two conductors.

It looks like you have individual conductors running between the boxes. If so they need to be changed to a cable.

Last edited by pcboss; 04-08-17 at 01:11 PM.
#3
04-08-17, 07:37 AM
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Thanks pcboss.

Pigtails or wires that are part of the switch do not count towards box fill.
They are individual conductors that attach (are not part of the switch)? I always thought of pigtails as coming off of a supply cable. Are they considered pigtails?

If so they need to be changed to a cable.
I plan to have only one box, so everything between the current boxes will be internal. So would they be considered pigtails?

#4
04-08-17, 08:10 AM
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Only wires (cables) that cross between the outside of the box and the inside of the box are counted for box fill calculations, unless you have internal loops that are longer than 12" for some reason.

#5
04-08-17, 08:25 AM
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Are you maintaining two switches ?
Then you'll need a two gang box which increases the amount of capacity for wiring.

#6
04-08-17, 09:15 AM
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Thanks CarbideTipped.

Yes still will have two switches. ???

#7
04-08-17, 01:15 PM
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Make sure you carefully label each conductor before you break any splices,or you will have problems when you try to reconnect.
Just a thought
Geo

#8
04-12-17, 01:37 PM
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Help with two speed motor switch

I've moved this a step forward. I've pulled all the wires from the three old boxes, deleted an extraneous connection to power an attic outlet (now everything is dedicated to the fan only) and then reassembled and tested everything as loose wires w/no boxes to be sure I didn't cross wire anything. I didn't!.

My next step is to reassemble the wires in a properly sized box for a timer switch and a fan speed switch (hi-off-lo). The old switch is a toggle switch. I want to switch to a paddle switch like this:

http://ehydrant.com/Leviton-5685-W.pdf

The toggle switch has 6 terminals and two have a jumper the new switch has (apparently) only 3 terminals. The wire to the fan is 14-3, so I'm guessing that white is neutral, and each of the others is low and high or one is low and both are high (?). Why neutral and hot wires would go to a switch is beyond me, but I followed the 2-wire feed cable.

So how do I change my wiring to go from a 6 terminal switch to a 3 terminal switch?

Thanks guys!

Attached Images

Last edited by syakoban; 04-12-17 at 01:54 PM.
#9
04-12-17, 04:42 PM
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I think we're going to need a labeled sketch showing the way it's wired now; very difficult to make out the pics in enough detail and we can't see where the other ends of the wires go.

In general you can't replace a DPDT (double pole, double throw; your 6 terminal switch) switch with a SPDT (single pole double throw; 3 terminal) switch when both halves are used. But maybe with a sketch we can sort it out.

#10
04-12-17, 05:10 PM
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I'll try and make a sketch, but don't know exactly what's what.

Meanwhile, are there DPDT lo-off-hi decora style switches?

What dictates that it has to be DPDT?

Thanks.

#11
04-12-17, 05:19 PM
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No need to switch the neutral. The speed wires may be backwards from what you have.

A decora or any three way switch could also be used in place of the switch you linked to.

#12
04-12-17, 05:30 PM
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Thanks PJmax.

I'm no expert but was shocked to see the neutral connected to a switch - I always thought a neutral is never switched.

Three questions:
1. If I trace the neutrals on the existing toggle switch, remove them, and then twist them together independently, the switch will still work. Correct?
2. If that flies, then a 3-way switch would then work, but have no off, which the timer would provide?
3. Does that mean that each fan speed uses one leg of the 3-way and the hot from the timer goes to the traveler?

#13
04-12-17, 05:34 PM
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1 - correct
2 - correct

The hot from the timer goes to the common of the switch.
Which speed operates depends on which way the switch is set.

#14
04-12-17, 05:40 PM
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Thanks again. That's a big conceptual breakthrough for me. It makes me think the original setup was overly complex.

So even more basic, if I pulled the 14-3 that goes to the fan and connect its neutral right to the neutral of the supply and then connected red to the hot supply I would get one fan speed (no off) and then disconnect, switch to black, would give me the other?

#15
04-12-17, 05:54 PM
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Yes...... that is correct.

That original fan speed switch is a universal one that could be used on 120v or 240v.
That's why it was a double pole type.

#16
04-12-17, 06:25 PM
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I just threw a 3-way on the fan wires and connected directly to the feed (timer is broken) using the breaker as an on off. Works perfectly!

Bye bye spaghetti!

#17
04-12-17, 06:34 PM
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Good job.

You can put a regular SP wall switch in place of the timer for now.