Options may include replacing the foundation; use of a special base adaptor; or, installation of epoxy set anchor bolts.
Bolt Circle: Larger than Required
If the existing bolts were set to a larger bolt circle diameter and the pole has not been produced, it is possible to either:
1. Select a similar pole that has a properly matched bolt circle for the existing foundation.
2. Produce the original pole with a modified anchor base plate using the new bolt circle requirement without need of a base adaptor.
If the pole already exists, then the pole can be adapted to the new bolt circle using a custom-sized adaptor spool that installs between the pole base plate and the new bolt circle. Or the existing bolts can be cut off at the concrete surface and HILTI bolts installed.
Bolt Circle: Smaller than Required
If the existing bolt circle is smaller than that required for the pole to mount, care must be taken to ensure the foundation and anchor bolts are not overstressed through the use of an adaptor spool. In cases where the bolt circle is more than 1” smaller than that required for the pole, it may not be possible to provide an adaptor. These situations need to be carefully evaluated on a case by case basis.
When choosing between a base adaptor and the use of HILTI products, some considerations would involve size of anchor bolt, aesthetics, time and cost. The base adaptor method is rather expensive, involves more time to produce the adaptor and delays the project. Additionally, the spool increases the mounting height of the fixture which may violate local building codes—requiring the pole to be field-modified if necessary. Ultimately, the customer may not accept the “bulky look” of a base adaptor. One possible option to the base adaptor is the use of a standard Transformer Base. While it is bulky like the base adaptor, it does present a much cleaner, finished look and can be supplied faster than a custom manufactured adaptor when time is an issue.
The HILTI system provides a clean transition between the foundation and the pole. However, the HILTI bolts have to be set within, or close to, the foundation’s rebar for strength and to avoid cracking the edge of the foundation. If the foundation is undersized, use of HILTI products may not be possible. Also, HILTI bolts are only available up to 1.25” diameter so poles requiring larger diameter bolts will necessitate the use of an adaptor spool or replacement of the foundation.