The NEC wants you to avoid overfilling a conduit so that the conductors can dissipate heat, and so you can remove a conductor without damaging it. See NEC 300.17.
There are only 9 single pole circuits (so 18 conductors?)
Ground conductors count for equipment fill, so you have more than 18 -- maybe 23?
Ironically, when you get close to a fill limit, the NEC actually wants you to increase conductor size, because that reduces heat.
Should I be worried or just put the cable through it anyways?
If this was my house, I would want to add a new conduit, if only because pulling the new conductor will be so much easier.
Do they make "reducing" hubs?
Yes. Here are some examples: http://www.thomasbetts.com/ps/endeca/index.cgi?a=nav&N=3819+598+4294951140&Ntt=
I've always found I needed 6" of conduit to make the transition between the reducer and the male fitting that connects to the box. Luckily my local hardware store will sell PVC conduit by the foot, so I don't have to buy a full stick for this.
As @Tester101 mentions, you can also make the hole bigger. A step bit is a nice tool, but 1 1/4" conduit requires a knockout that's actually ~1 3/4". The one he linked to only goes to 1 3/8", and I haven't seen bigger.
The professional way to make a larger knockout is to use a punch. They're a little expensive. Maybe you can find an electrician who will punch the hole for you in exchange for beer or a favor. Or maybe a tool rental place will have a bunch for you.
You don't have to bring the conduit in through an existing knockout - you could punch a hole on the side in a blank area, if that's more convenient for you. Alternately, if there's a good spot with 2 small knockouts, you can consume that whole area.
In your existing installation, I think the lock washer is upside-down. There are sharp edges that are intended to bit in to the metal, so it won't come loose. Unfortunately fixing this means undoing a lot of wiring.
Also, I think you should use a bushing to protect the conductor from the end of the conduit. Whether your inspector will require it is difficult to guess, but it's seems like cheap insurance. Something like this:
Also, I hope that if you're going through the trouble of pulling a big conductor to a new location, you're installing a subpanel at the other end. Because subpanels are awesome.
Best Answer
You can see right there where the steel cable is bonded to the lighter colored of the three service entrance wires.
Yeah, you lost a neutral. This is when we get out the big font and say
This is a power outage. Call your power company NOW.
Normally these arise as “Hey, my appliances keep blowing up”... or “I measured 84 volts on an outlet” “check your other ones” “Oh, this one is 148 volts”.
But the funny thing about lost neutrals is people can take quite some time to realize they have the problem.
But yes, that wire is electrically “hot” - well, it’s near ground voltage if everything is working... but if you go up there and try to rejoin it, you’ll end up with one wire in your left hand and the other wire in your right hand, and the neutral current will try to go through you.
Of course, you said “feeder”. That is a word with a specific meaning: it means a cable after the meter going between panels. So supposedly you would have a house and a pole barn or something, and an overhead line feeding a subpanel out there. But that would be 4 wires (with messenger as ground), not 3 as we see in this photo.
The specific name for this cable is “service drop”.
And the service drop is in the power company’s bailiwick, so they will fix it for free in almost every case.