Thread: Double Tap and Bundling Madness

I counted 12 double taps in this panel which is a record for me. And every cable was brought into the box through the 4 main holes at the top of the box.

Nick are you sure those breakers don't allow two wires? I can't tell from the photo but it looks like it might be one of the few that has provision for two wires.

They were not Jim. I looked closely at the breakers and they did not have double lugs, only a single round hole for the conductor connection.

Good chance you have a derating issue with the supper bundling. Connectors most likely are not listed for that many wires under there. Siemens QP breakers are not rated for 2 conductors under 1 terminal if Im thinking of the correct listing for QPs.

Just trying to learn a little something here. How many wires can you put through one connector? I'm sure the different size connectors are rated for a different number of conductors/wires based on their size, but is there a general rule of thumb?

Thanks

Luke

Originally Posted by lukerabun

Just trying to learn a little something here. How many wires can you put through one connector? I'm sure the different size connectors are rated for a different number of conductors/wires based on their size, but is there a general rule of thumb?

Thanks

Luke

Its usually up to the listing of the device, sometimes the NEC. The number of wires on a breaker is based on the listing of the breaker. Most only can take 1, however Square D QO and Square D Homeline 15 and 20 amp can take 2 copper conductors of the same size if placed correctly on the screw plate. Neutral bars are always 1 per hole, ground can take more if the panel board says its ok too.

What does derating actually involve?

Originally Posted by Nick Ostrowski

What does derating actually involve?

To keep it simple it involves keeping the conducters spaced apart, ie entering different holes and not huddled together so tight in large packs.

Similar procedure followed with conduit. If more wires are put in conduit those wires are either sized larger or put in another conduit to keep the overall count low.

Issue comes from overheating. Less of a risk in residential as appose to commercial where circuits are loaded more but still not up to code.

Since the conductors do not have the space to radiate the heat when grouped together the code makes an installer derate or lower the ampacity of the conductors from the Table 310 chart. The more conductors the less they are allowed to carry.

Derating is not an issue when the conduit or nipple is 24" or less in length.

Originally Posted by Jim Port

Derating is not an issue when the conduit or nipple is 24" or less in length.

Thanks, Jim.

Forget bundling and nail him for double taps.

Cutler Hammer also makes a breaker that can take two wires. Square D or CH only.

Originally Posted by lukerabun

Just trying to learn a little something here. How many wires can you put through one connector?

Typically two with #12 or #14

Originally Posted by lukerabun

Just trying to learn a little something here. How many wires can you put through one connector? I'm sure the different size connectors are rated for a different number of conductors/wires based on their size, but is there a general rule of thumb? Thanks Luke

Luke,

If I understand your question correctly, you are referring to the number of cables that can exit through an opening in the panelbox. That, too, is up to the listing/manufacturer. The strain relief clamps typically allow 2 flat (2 wire + ground) or one round (3 wire + ground) through an individual opening.

Any thoughts about the painted cables? Looks like all yellow sheathing inside then white on the outside, guessing it was painted, or am I seeing an optical illusion?

One thought is if they are painted are you sealing them all together, no chance of air moving through, creating a pseudo conduit situation, unless the bundle is under 24" then it's not an issue.

Other opinions???

You are correct Mike. The cable sheathing was painted.

Hey Nick, I see the neutral bars but don't see any ground wires from all the branch circuits going anywhere. Were they cut off or are they hidden and the photo doesn't show them? Just wondering.

Originally Posted by Mike Borchardt

Hey Nick, I see the neutral bars but don't see any ground wires from all the branch circuits going anywhere. Were they cut off or are they hidden and the photo doesn't show them? Just wondering.

The grounds are there. Just tucked behind the bundles.

Can barley see it behind the wires but there are extra ground bus bars