Main wire tapping lugs

These main feeder wires were tapped to feed a 50 amp hot tub disconnect right next to the panel to the left (wires obviously sized for the 50 amp breaker). They look like they were professionally done. Anyone ever seen anything like this or what exactly are they? I’d appreciate any helpful insight? TIA.

bump… should’ve posted in Emergency section. Anyone?

Those are called feeder taps and a feeder tap rules apply. If done correctly (sized, torqued, etc…), it should be code compliant.

Those are insulation piercing taps, they are UL listed and the install looks clean to me in that picture as long as the wire size and torque is correct. My question would be did the hot tub disconnect panel next it have a 50A GFCI breaker in it, or if not does the hot tub have internal GFCI protection?

Here is more info on the tap if you like:

Its an IPC 4/0-6 so its good from 4/0 through #4 (run) to #6 through #14 (tap)

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Thanks fellas.

There is a code violation with the tap. The green #10 EGC run along with the tap conductors is too small which is common error that I see very often when someone installs a tap. The EGC is sized based on the OCPD ahead of the tap (in this case it appears to be 200 amps) not the 50 amp OCPD in the disconnect. If it is 200 amps then T250.122 tells us that the EGC is required to be a minimum of #6 AWG. The EGC is not required to be larger than the tap conductors.

250.122(G) Feeder Taps. Equipment grounding conductors run with feeder taps shall not be smaller than shown in Table 250.122 based on the rating of the overcurrent device ahead of the feeder but shall not be required to be larger than the tap conductors.


How does this tap setup work?
The 50A breaker will protect the wires past the 50A breaker.
But both the tap wires and the EGC are smaller. Were there dead short in the conduit between the tap and the 50A breaker, how would that trip the 200A breaker without first heating the tap wire?

That’s why the EGC is sized according to the OCPD ahead of the tap not the OCPD after the tap. By doing so you will ensure that the EGC is large enough to open the OCPD.

That’s what I’m having trouble with. If I created a dead short from one of the tapped hots to neutral, the current would flow in a loop. Would that not mean up to 200 amp could flow through the ground, and 200 amp flow through the small tapped wires as well?

While the breaker would probably trip super fast, it seems that 200 amps could be flowing through any of the wires (hot, hot, hot tap, hot tap, EGC or neutral). What am I missing here?

I know that this is confusing so let me see if I can explain it.

  1. If there is a fault between a hot and a neutral tap conductor the 200 amp OCPD will trip. There is no current flow on the “ground” because it is not a ground fault.

For the instant that the CB is still closed thousands of amps will flow through the hot and neutral because the only limit to the current flow is the resistance of the conductors. This is why the EGC is not required to be larger than the tap conductors because the current flow in a short circuit condition (Hot to Neutral) will be nearly the same as the current flow in a ground fault condition.

  1. The fault current (thousands of amps) will flow only between the hot and the neutral. The hot tap conductor is fed from the 200 amp circuit breaker so that would trip.

Does that make sense?


Thanks for your expertise, Rob. We appreciate it. :+1:

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That’s a great point Robert, I missed seeing that when I first looked at it, I’m glad you pointed it out.