Split Bolt Connector usage

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Strathead

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Electrician/Estimator/Project Manager/Superintendent
Can you use a split bolt connector for more the two wires. Say I have a 750KCMIL main and I need to tap off two 200 Amp services. Can I use one split bolt for both 3/0 wires?
 
I do not know of any split bolts listed for more than two conductors.

Of course they were used that way for years but it is a code violation.
 
jumper said:
Only if the split bolt is listed for the combo you described-and I doubt it.

Think Polaris connectors or similar IMO.
Click to expand...


I wish. Existing illegal installation where a #3 is tapped from a 750 in the middle of the wire, then the #3 is tapped with a 1/0. One feed a 150A service one feeds a 100A service. Polaris won't co in the middle of the conduit and I know of other solutions too, but down time is an issue. Removing the original Kearny and installing a single new one much easier than stripping more and installing two new ones.
 
NO PROBLEM.

NO PROBLEM.

Strathead said:
Can you use a split bolt connector for more the two wires. Say I have a 750KCMIL main and I need to tap off two 200 Amp services. Can I use one split bolt for both 3/0 wires?
Click to expand...

Sure you can:

1) connect one end of 3/0 wire to one service, other end to other service.
2) find a place in the 3/0 and the 750KCmil where you can place a split bolt at the same time.
3) remove insulation from both cables appropriate to the size of the split bolt.
4) place the split bolt over 750, add separator,
5) place 250 in split bolt.
6) place nut in split bolt.
....

Repeat for each tap.
 
GoldDigger said:
You are saying that a single 3/0 cannot handle 200A? Or that the 750 cannot handle 400A?
The 3/0 in each direction is a tap, terminating on an OCPD.
Click to expand...

First off let me make perfectly clear I have done and would do again what fmtjfw describes. :cool:

It works fine. :thumbsup:


But now ... lets just talk about code compliance.

Where does one conductor start and one conductor end?
 
iwire said:
Hmm.

If we say that is 'one wire' it is overloaded by a factor of two.

If we say it is two wires it is a listing violation for the connector.
Click to expand...

Unless this is a very strange bolt connector, it is also rated for connecting two 750kCmil conductors together.
Let's look at T310.15(B)(16) under the 75?C column for 3/0, we find 200A; and for 750 we find 475A.
Fine, now we can believe the split bolt is rated for connecting 475A conductors together.

However we run into a problem, I'm unable to find a split blot connector that will join a 750 & a 3/0. The closest is 750 & 4/0.

We have to modify the plan.

I believe the OD of a 3/0 uninsulated crimp butt connector is about the OD of 4/0. So if we cut the 3/0 conductor (where we would have stripped it in the original plan and butt splice it back together, we now have effectively increased its diameter to 4/0 and may be able to use a 750 split bolt [have to check if 4/0 can only be stranded according to listing].

Pretending that the listing allows solid conductor, we now have the two 3/0 conductors jointed in a listed manner suitable for their full amperage rating. And we are clamping the butt connector / size expander in a split bolt connecter rated to connect two 475A conductors for their full amperage rating.

What's not to like?
 
fmtjfw said:
What's not to like?
Click to expand...

I do like it and have done it.

But forget that and deal with words, I know you like NEC to be concise and correct with words. :cool:


In your 3/0 suggestion in post 6, is it one conductor or two?

If it is two conductors where is the start and end?
 
Loctite?

Loctite?

Actually with split bolt connectors, I've found to many of "old" split bolt connections loose. I don't know if they were improperly torqued in the beginning or thousands of heating / cooling cycles have worked them loose.

If I were to use split bolt connectors (which I rarely do) I would tend to put loctite on the threads.
 
fmtjfw said:
Actually with split bolt connectors, I've found to many of "old" split bolt connections loose. I don't know if they were improperly torqued in the beginning or thousands of heating / cooling cycles have worked them loose.

If I were to use split bolt connectors (which I rarely do) I would tend to put loctite on the threads.
Click to expand...

The only time I would use a split-bolt now is for a tap. I don't have the means to use a crimp tap.

I have used the insulation piercing taps in 2/0 through 500 sizes and they don't impress me for permanent work. Quick temp repairs they are nice for.


I do like Polaris style connectors, even uninsulated ones.
 
iwire said:
I do like it and have done it.

But forget that and deal with words, I know you like NEC to be concise and correct with words. :cool:


In your 3/0 suggestion in post 6, is it one conductor or two?

If it is two conductors where is the start and end?
Click to expand...

For the original plan which I assume is post 6, it is a single conductor. There is no break between each end of the conductor connected to the two services.

The real question here is: how are the current flows from the split bolt connector distributed in that single conductor. Since electricity flows in all available paths, inversely proportional to the resistance, I would expect for the current flowing into the part of the conductor feeding to the right of the connection to be the following:

1) a minimal current flowing in the conductor at the left of the connector
2) a maximal current flowing in the conductor at the right of the connector
3) the current gradient ranging from 0 to 200A (assuming full load on the "right" service).

I would assume the same would occur reversing left and right for the part of the conductor feeding to the left.

In a perfect world these two gradients would match and the maximum current at any one point would be exactly 200A.

Not a prefect world, so some places in the 3/0 in the connector may be more that 200A. But that may require the connector to be loose enough to provide hot spots in a single direction scenario. And in a not so perfect world, services are rarely even close to being maxed out.
 
fmtjfw said:
The real question here is: how are the current flows from the split bolt connector distributed in that single conductor. Since electricity flows in all available paths, inversely proportional to the resistance, I would expect for the current flowing into the part of the conductor feeding to the right of the connection to be the following:

1) a minimal current flowing in the conductor at the left of the connector
2) a maximal current flowing in the conductor at the right of the connector
3) the current gradient ranging from 0 to 200A (assuming full load on the "right" service).
Click to expand...

So you understand, but does the NEC?:D

You have one physical conductor rated 200 amps with 400 amps of overcurrent protection connected to it.

240.4 Protection of Conductors. Conductors, other than
flexible cords, flexible cables, and fixture wires, shall be
protected against overcurrent in accordance with their ampacities
specified in 310.15, unless otherwise permitted or
required in 240.4(A) through (G).
Click to expand...

It says nothing about resistances, impedance's or current direction, it just says what it says.
 
iwire said:
So you understand, but does the NEC?:D
You have one physical conductor rated 200 amps with 400 amps of overcurrent protection connected to it.
It says nothing about resistances, impedance's or current direction, it just says what it says.
Click to expand...

You are, of course, playing the devil's advocate. I'm fine with that. It was an ancient and honorable office.

You will note that at any cross-section of the 3/0 wire is protected from overload by a 200A OCPD, since each end of the wire is connected to a service so rated. The only possible exception is about 1 inch of wire in a big, hulking $100+ chunk of copper heatsink.

Of course, the NEC does talk about resistances, impedance's, and current direction.

Ch. 9 Table 9
100 Effective Ground-Fault Current Path.
220.61
 
fmtjfw said:
Of course, the NEC does talk about resistances, impedance's, and current direction.

Ch. 9 Table 9
100 Effective Ground-Fault Current Path.
220.61
Click to expand...

None of which have a bearing on 240.4 so forget the distractions. :p

I thought you were a huge advocate of making the NEC 'right'? Here is a case where it may not be.
 
iwire said:
None of which have a bearing on 240.4 so forget the distractions. :p

I thought you were a huge advocate of making the NEC 'right'? Here is a case where it may not be.
Click to expand...

The situation we are discussing is a feeder in the form of a service-entrance conductors being tapped to smaller feeders, also service-entrance conductors.
230.46 Spliced Conductors. Service-entrance conductors shall be permitted to be spliced or tapped in accordance with 110.14, 300.5(E), 300.13, and 300.15.
None of the references in 230.46 aid this discussion.

I read the tap conductor definition to exempt service [entrance] conductors from the source side OCPD requirement that generally applies to tap conductors. This conforms to many multi-service installations containing 6 or less services.
240.2 Definitions.
Tap Conductors. As used in this article, a tap conductor is defined as a conductor, other than a service conductor, that has overcurrent protection ahead of its point of supply that exceeds the value permitted for similar conductors that are protected as described elsewhere in 240.4.

iwire posited this section as the one governing the taps.
240.4 Protection of Conductors. Conductors, other than flexible cords, flexible cables, and fixture wires, shall be protected against overcurrent in accordance with their ampacities specified in 310.15, unless otherwise permitted or required in 240.4(A) through (G).

as they are taps, section (E)(3) governs:
(E) Tap Conductors. Tap conductors shall be permitted to be protected against overcurrent in accordance with the following:
(3) 240.21, Location in Circuit

240.21(B) allows load end OCPD for taps which meet proper requirements.
240.21 Location in Circuit. Overcurrent protection shall be provided in each ungrounded circuit conductor and shall be located at the point where the conductors receive their supply except as specified in 240.21(A) through (H). Conductors supplied under the provisions of 240.21(A) through (H) shall not supply another conductor except through an overcurrent protective device meeting the requirements of 240.4.

(B) Feeder Taps. Conductors shall be permitted to be tapped, without overcurrent protection at the tap, to a feeder as specified in 240.21(B)(1) through (B)(5). The provisions of 240.4(B) shall not be permitted for tap conductors.

For sake of argument I assume either tail of the 3/0 conductor does not exceed 7.5 m
(2) Taps Not over 7.5 m (25 ft) Long. Where the length of the tap conductors does not exceed 7.5 m (25 ft) and the tap conductors comply with all the following:

The maximum OCPD for 750kCMil CU 75?C conductor is the next higher standard size above 475A. Looking in 240.6 (A) I find that to be 500A. The maximum current rating for 3/0 CU 75?C conductor is 200A from 310.15(B)(16). Using the 500A value as the conservative choice I get 200/500 or 0.4 ratio. The required ratio is 0.33 so the (1) requirement is met.
(1) The ampacity of the tap conductors is [red]not less than one-third[/red] of the rating of the overcurrent device protecting the feeder conductors.

I assume this to be the case, information not provided.
(2) The tap conductors terminate in a single circuit breaker or a single set of fuses that limit the load to the ampacity of the tap conductors. This device shall be permitted to supply any number of additional overcurrent devices on its load side.

I assume this to be the case, information not provided.
(3) The tap conductors are protected from physical damage by being enclosed in an approved raceway or by other approved means.

I posit that the 3/0 conductor never carries more than a 200A OCPD will allow along its length, with the possible exception of a part in a 1 inch connector. I further claim that the suggestion of a total of 400A of OCPD ignores the geometry of the situation.
 
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