PVC electrical fittings for making corners

[Julie Moriarty]

Here is one of these 'unilet' boxes used as a junction box. My wires to this sub-panel were just a bit too short so I used one of these (this is a 1" box) to extend the wire.

The sub-panel and this 'unilet' used to be on the side of my house and thus got painted but I moved them into this plastic shed (my swimming pool equipment shed).

So right or wrong, there it is...working just fine.

That unilet is called a "C". It is usually inserted in a long conduit run, just in case the wire pull becomes difficult. It can also be used to get by the 360⁰ rule - no more than 360⁰ of bends between junction boxes, panels, cabinets, etc. But I never inserted a "C" for getting by the rule if I thought the wire pull would stress or stretch the wires.

The NEC saying what it will, my personal experience is it's bad practice to use unilets as splice boxes. The "T" unilet can be called a junction box because it is the junction of (3) conduits but there's just not enough room to safely make a splice. But splicing in a unilet is something I learned should be avoided.

There are many practices you learn in the field that are contrary to the NEC. That's why some municipalities edit or rewrite the code. Experience tells you sometimes the NEC shouldn't be gospel. Just my two cents.

BTW, unilets are considered fittings, not boxes. At least that's what we call them in good old Chicagoland.

[Anthony Whitesell]

(b) 6" for 3/4" EMT bender

Thank you.

[Murray Roblin]

Julie,
I'm trying to understand your comment:

But I never inserted a "C" for getting by the rule if I thought the wire pull would stress or stretch the wires.

In the case where you were concerned about stressing or stretching the wires, what do you do? Do you install a JB as a pull point where you would have put a C body? Or are you just talking about electricians who install the C body and don't use it - just pass the wires through it without opening it up as a pull point?

Another question: I've got more than 360 deg in a single run. I can either install a JB or c-body before an elbow to act as a pull point, or I can simply replace the elbow with an LL and use that as the pull point. What is the best practice here? (This is in a 24" crawlspace, so using the pull point is going to be unpleasant no matter what.)

Thanks,
Murray

[Julie Moriarty]

Hi Murray,

Some job foremen will tell their electricians to insert a C fitting so they can get by the 360^₀ rule. Then, when it comes to pulling the wire, they will pull straight through the fitting. In some cases this stresses the wire and can stretch it, even to the point strands are breaking. If the wire stretches, the diameter of the conductor is reduced. In both cases you have changed the physical properties of the wire and affected its current carrying capacity.

I've never been much of a fan of unilet fittings. I use them when space constraints make them the better alternative. If I have the space, I will install a JB. The JB gives you more room to work and offers the option of tapping into it some time in the future. Versatility is a good thing when building a conduit system.

When laying out the work for a job, my attitude is to make each successive step easier, relative to the task. So the conduit install would take the most time, which would make the wire pull easier, which would make the trim job easier. In the long run, it saved on labor. Some foreman would skimp on the conduit install and make the wire pull a bear and the trim harder because the boxes would be stuffed with splices.

For your crawl space, look at placing JBs near the access, if possible. To satisfy the 360⁰ rule, you may place the JB right after the first 90⁰, close to the access, then put the rest of the bends further into the crawl space, where you won't have to crawl back into to pull the wire.

Unilets have their place but if you can install a JB, I recommend doing it.

[Murray Roblin]

Thanks Julie,
This is exactly the info I was looking for. I can find the code and can usually parse it, but I don't have the experience to know what approach will work best.
Murray