Temporary Electric Power

When a new home is constructed it is necessary in most cases to erect what is known as a Temporary Electric Service Pole (TSP) on the construction site. This power source would be used by the carpenters, plumbers and yes, even the electricians and others, during the construction process.

A TSP is basically a small electric service, with a socket for the utility company’s electric meter, a small circuit breaker panelboard with two or more GFCI-protected receptacles for both 120 and 240 volt electric power tools. When constructing a TSP, consult with the Electric Utility Company (EUC) in your area beforehand, they all have installation guide booklets, explaining all of the company’s required specifications.

The temporary service belongs to the person who paid to have it built, (the electrician in most cases) and remains as such after the equipment is disconnected from the grid. Hence the term ‘temporary’ because once the permanent service to the building is connected, the TSP is disconnected and can be removed from the construction site. The TSP is generally disconnected from the grid once the permanent power to the structure being built is connected and operational. An electrician by NEC must install a board receptacle, or a GFCI reeceptacle, mounted on the plywood backing for the panelboard.

Sometimes mounted on a 4" by 4" or a 4" x 6" post, with roughly 24" of the post buried in the ground, the TSP should be braced for stability with driven stakes and additional support members. Remember that this perpendicular post has to support the weight of the service drop-cable, and, the length of this cable could be a factor if there is a long distance to the utility pole; the longer the distance, the heavier the load. The maximum overhead cable run is usually in the 100 foot to 125 range, depending on the EUC. The height of the TSP post is also a factor, since the minimum distance above ground for the service drop-cable must be no less than twelve feet at its termination point on the post. If the cable drop must cross over a street, or commercial parking lot, the minimum distance above those areas would be even higher at 18 feet for the cable itself. Therefore the connection point at both the TSP and the utility pole would be higher to provide the required 18 foot clearance (lowest point) of the drop , as mentioned.

The TSP could contain only one circuit, but, depending upon the size of the project, there may be many 120 and 240 volt receptacles, with multiple circuits; remember we are only talking about residences here, not high rise buildings.

Once erected, the TSP equipment must be grounded through the use of a made-electrode, or ground rod. The ground rod, measuring 8' long x 5/8" diameter, must be driven near the TSP and connected with an approved fitting (ground clamp) by a bare copper grounding electrode conductor. A #6 AWG is best, although oversized, and it needn’t be in conduit for mechanical protection. The bare #6 conductor is led into and connected to the ground strip in the panelboard, or at any point along the grounded comductor, neutral (white) conductor.

A TSP is usually, and should be, installed as close to the proposed building site as possible, but out of the way of the construction process, excavations, trenches and any equipment staging areas, etc.. Keep in mind that the workers will have to run extension cords to and around the work site, keeping them as short as possible is the best way to save the electric tools.

The longer distance between the source and the power tool causes what is known as voltage "drop". This drop, or dip in voltage, will cause harm to the electric power tools that are in use, because there would be an inversely proportional spike in current flow through the windings of the tools’ electric motor, which can burn them out. It is for this reason that you should always put the TSP as close as practically possible to the building. This will reduce the cord length of the workers’ tools, and keep them from burning out.

As mentioned earlier, the receptacles provided for the workers, including both 120 and 240 volt receptacles, must be, by National Electrical Code standards, GFCI protected. This is for the safety of the workers; it protects them from accidental electrocution.
For the connection-after-inspection process to begin the electrician, or electrical contractor, has to apply for an electrical permit to install electrical wiring, from the town or city building inspection department. For the electrician there is a usually a fee to pay, and an application form to fill out. These days the electrician must show proof that:
1) He has a Liability Insurance for his company or corporation
2) That he has his employees covered by a Worker Compensation Policy.
Once permitted the work needs to be inspected and the only person that can contact the power company and authorize the connection of the service to the utility, is the Inspector of Wires! Once notified by the electrician that he/she is ready, the inspector first looks at the installation and he calls or faxes the readiness for hook-up to the electric utility. No Connection Without Inspection!
If the site already has a source of electrical power, such as a neighbor’s house from which you can get a safe source of electricity, and/or if the construction workers are accustomed to working with an electrical generator, there are times when a TSP is not necessary. This may be a consideration if you realize that the EUC is going to charge you money to connect and disconnect the TSP, unlike the main service to your house. The fee to hook up and disconnect a TSP is in the $100.00 to $300.00 range, again according to the EUC’s going rates in your area. The electrician usually pays the fees for the permit application, and the EUC’s fees for the TSP connection / disconnection, and includes them in his price.