Searching for the best Precast Concrete Connection Box Chamber Supplier?
The only purpose of a connection box chamber is to safely bury, protect, and allow a technician to access cable joints, valves or pipe connections years later without the struggle.
If it does then nobody will see it.
If it doesn’t it is NOT the chamber’s fault, it is the supplier’s fault who builds it.
This guide explains how to judge a precast concrete connection box chamber supplier, and ensure that you receive a unit that will not fail to hold up underground – but instead cause issues the first time you need to open it up.
There’s More to Choosing a Supplier Than Inside Dimensions
The first thing most buyers look at is the internal dimensions, cover load capacity and cost per unit.
That’s a good beginning, but it misses what really matters, how the supplier reinforces, seals and finishes the concrete to resist the loads thrust upon it during burial, and the effects of groundwater and repeated access throughout its life in service.
It is easy to underestimate the stresses underground chambers must take.
The constant loading and unloading of vehicles and people, soil pressure on the walls, groundwater pushing through joints and continual opening and closing of the unit by technicians are all cumulative.
When the supplier thinks of connection chambers as a section of ground, and not simply a concrete box with a lid, he or she is designing for such conditions.
One that does not will come to you with a chamber that seems to be level when it is installed and begins to wobble at the cover seat, crack at the cover seat or leak water in the first few years.
Know Exactly What Type of Chamber Your Project Needs
But before going into the supplier comparison, there is a need to determine the scope of your project because not all precast manufacturers are able to produce the entire range of chambers.
Cable Joint Chambers
Electrical and/or telecom cable joints and splices are installed in cable joint chambers.
They require generous bending radius for cables, cable entry ducts that conform with the route design and appropriate cover load ratings for installation beneath a footpath, a driveway or a road.
Valve and Pipe Connection Chambers
Isolation valves to water, gas or drainage networks are installed in valve chambers.
They must be fitted with penetrations that are perfectly aligned for pipe entry/exit, have adequate internal clearance for access to the equipment and may require special basework to allow for the attachment of fixed equipment without bearing on the pipework directly.
Pull Boxes & Access Chambers
Pull boxes and access chambers are typically used for pulling cables, inspection or future connections, not permanently.
Their first need is a simple cover system and size that will allow ease of future cable or pipe work, not a tight fit.
Combined Utility Chambers
Multiple services (power, telecom, water) are combined in a single structure, called combined utility chambers.
These need to be segregated internally or arranged within a duct that complies with the applicable utility spacing requirements.
Compliance and safety concerns may occur if the services are not segregated.
After determining the appropriate category (or even the combination) for your project, you can quickly reduce your list of potential suppliers to those that specialize in underground utility structures, instead of those that sell chambers as a secondary item to a larger precast catalogue.
When Designing Reinforcement and Loading, Ask Questions About Their Design
A supplier that treats chamber manufacturing seriously will design reinforcement and thickness for the actual load class the chamber will experience in use, and not use a generic design for all pedestrian, driveway and road applications.
This typically results in variations in reinforcement schedules, cover thickness and duty rating for each cover thickness, and a rating of cover and frame to match.
Directly inquire about the load class (pedestrian, light traffic or full traffic) the chamber is designed for, how the reinforcement is protected by the cover, and whether the cover and frame are rated the same as the chamber body.
The supplier that provides you with particular ratings will be talking your language.
Whenever someone claims the unit is “heavy duty,” without any numbers to back it up, they need to be asked some more questions.
Consider How They Handle Sealing and Water Ingress
One of the most crucial things to seal out for any chamber that is being buried is ensuring it is watertight and that surface water and groundwater cannot get in, and one of the most basic things that can be overlooked.
Question the sealing of duct and pipe entry points, the method used to seal base to wall and wall to cover joints, and if water tightness of chambers is checked prior to their departure from the yard.
Some vendors come with pre-formed rubber duct seals and gasketed joints as standard and are able to provide test data to support.
Others hope that it will fit tightly and take their chances.
Both are potentially viable in practice, but not an assumption—a documented answer is desired, particularly in chambers with electrical joints or delicate equipment that would be impacted by water damage.
Check Their Manufacturing Quality Control Procedures
The same spec sheet can be used for two chambers and they can be quite different when it comes to performance, depending on how they are actually cast.
Inquire about unit casting, curing process and inspection procedures prior to unit dispatch.
The dimensional accuracy is important here but not as much as one might think.
The slightly out-of-square or misaligned cover seat will create installation problems and rattle or misalignment over time.
The finish is very dense and well cured, which means that it’s much more resistant to cracking at the lifting points and duct knock-outs during transportation and installation than it would be in a rushed pour.
All these information give you an idea of the discipline of the supplier’s manufacturing process.
Request Site-Specific Drawings, Not a Standard Catalogue Sheet
A good supplier will be able to deliver drawings and load calculations that are appropriate for your particular installation rather than a generic catalogue page.
This should include duct entry positions appropriate to the route design, cover load rating appropriate to the actual route (footpath, driveway or carriageway) and, where applicable, groundwater or soil bearing considerations for the base of the chamber.
Suppliers who are capable of creating this level of detail uncover issues at the site before installation, including misaligned duct entries, wrong load class and poor bearing conditions, etc.
Any supplier who can provide only an “off-the-shelf” drawing is probably not making one for you, but rather for someone else’s project.
Compare the Requirements for Installation and Bedding
The requirements for the installation vary from one type of chamber to another.
In some instances, a compacted granular bed will suffice and in other instances, a concrete surround, specially compacted backfill, or precise level tolerances are needed to maintain a cover flush with finished grade for larger pull boxes, valve boxes or combined utility boxes.
Inquire about the bedding and backfill used, if they offer any instructions for installation, and if they have used contractors who are familiar with their product on other utility projects.
If a seemingly simple chamber requires a full concrete surround, it isn’t a discovery you want to make while on site.
Investigate Their Track Record and Reviews
Effective reinforcement schedules and sealing specifications inform you what a supplier can do.
Installed projects give you a report on what they actually provide.
Request for examples of other chambers supplied for service or facility projects, and include photos that are taken some time after the cover is installed, not on the day the cover was placed.
Carefully examine how those chambers have fared – level covers, no cracking around the duct entries, no signs of water ingress.
A chamber that has served traffic and access for years without any trouble, speaks far louder than any spec sheet.
There Are a Number of Red Flags That Should Be Monitored
The few indicators that can be more indicative of an unreliable supplier are:
- When questioned about load class or cover for reinforcement, they answer vaguely.
- They are not willing to confirm water-tightness testing.
- They have not clearly outlined how they match duct entries with the route design.
- The price is significantly lower than other suppliers, and no explanation is provided for the difference.
Each one of these should not rule out an automatic disqualification of a supplier, but if you see two or three of these in one supplier, you should take your time and ask more questions before you place an order.
It’s Time to Put It All Together Precast Concrete Connection Box Chamber Supplier
It involves understanding exactly what your project requires; confirming that the supplier designs for the specific load class and burial conditions that the precast concrete connection box chamber will be exposed to; knowing that it includes proper reinforcement, verified sealing, and attention to manufacturing care and quality, and that it has site-specific drawings for each chamber, not a catalogue listing.
Do it right – then your chamber does what it’s designed to do – sits quietly below the earth, keeping all its contents safe, ready to be opened cleanly when needed.
