Preparing Your Site for Generator Installation

Site planning/preparation varies depending on the generator system, for those that must withstand weather and those installed inside a building or shelter.

The 3 types of generator systems we'll be examining are:

1. Enclosed Permanent Generators - This is a fully self-contained backup generator, protected by a full soundproof enclosure and resting on a concrete pad or slab.
2. Enclosed Portable/Mobile Generators - These generators are usually mounted on a trailer or lorry frame, complete with sound/weatherproof enclosure. These require relatively little site preparation and planning.
3. Permanent Generators Installed Inside a Building - These require extensive site preparation and planning. They may include a redundant backup generator, and have considerable ventilation and safety concerns.

Site Planning Issues

Before you start planning, double check the national and local planning guidance, and the manufacturer's safety and usage documentation. Actual planning starts with a drawing of both the generator itself and all of its support systems. Remember to address:

• The fuel supply must be accessible by fuel truck.
• Include provision for a security fence.
• Decide on above-ground or below-ground fuel and electrical connections at this time.

Much of this will be dependent on the actual generator you are using. A typical 1250 kVA (1000 kW) generator set might have these requirements:

• Generator dimensions: 6.5m by 3.5m
• Generator & fuel tank total weight: 20,000kg
• Fuel consumption rate: 320 litres per hour

Remember to check both national and local regulations when planning your diesel generator site. Pay special attention to fuel spill containment - as 16 hours of operation can easily require 6000 litres of fuel (or more, for very large generators), spill containment can be a real challenge.

Planning the Concrete Pad

It is almost certainly against local building codes to set an industrial standby generator on gravel. It is definitely a bad idea, even if it is legal. It is vital that the generator be kept level, and its vibration when operating will quickly destabilise a gravel base. Concrete pads are the industry standard for most soil conditions.

Local conditions will drive the size and thickness of the pad you need. The pad should typically be 1.5 times ('half again') the length and width of the generator itself. Look to an expert who can assess soil composition, density and other geographical concerns. Also look at:

• The ambient temperature of the concrete pour.
• The use of vibration to remove bubbles.
• Whether the concrete must be reinforced.

National and local planning regulations must also be consulted.

Anchoring the Diesel Generator to the Pad

Typically, the generator and fuel supply are both attached to the pad via concrete anchors. There are three main types of these anchors:

1. Heavy duty concrete anchors - These must be installed before the concrete is poured. Measurement and placement must be exact.
2. Adhesive bond anchors - After the concrete has cured, a hole is drilled, and studs are affixed using epoxy. The studs must be perfectly level and square.
3. Mechanical bond anchors - After curing, the concrete is drilled, then the mechanical stud is set and tightened. These are the least robust of the three types.

Site Planning Issues

These require less in the way of site preparation than other types, as they are not permanent structures. They can be found from as little as 375 kVA (300 kW) to as much as 2500 kVA (2000 kW) capacity, depending on their intended application.

Site Preparation Issues

One of the biggest advantages of a portable/mobile genset is that it can be moved around the site as required, and as your power needs change. Assuming you need a large (2500 kVA) generator for construction or similar purposes, your site preparation should include:

• Making sure there is good road access to the site.
• Making certain there is sufficient headroom and side clearance both in transit and on site.
• A large genset might weigh 30,000kg or more. Depending on ground conditions, the rear wheels may require dunnage as well.
• A large generator may burn through 650 litres of fuel per hour, and up to 13,000 litres in a working day.

Generator systems for installation inside larger structures are typically self-contained. That means the generator, fuel system, engine, and cooling system are all aligned carefully and mounted on a skid at the factory. This skid must be moved to the facility, so consider the following:

• Headroom and side clearance to get the generator skid onto your concrete pad.
• Lifting equipment - typically a portable gantry, overhead crane and/or large forklift will be needed to remove the skid from its transport and manoeuvre it into place.
• Ensure the concrete pad is located so as to allow required maintenance of all parts of the generator, and is compliant to all relevant regulations.
• Attach generator skid mounts to the pad, according to the manufacturer's specifications. Measure and square them carefully.
• Ensure the room has adequate incoming air supply to support the generator in full operation.
• Ensure the fuel supply system is up to all relevant codes and regulations. This may require underfloor mounting and the trenches covering with grates.
• Be ready to run electrical drops after genset installation.
• Install cooling air ductwork and louvres.
• Install a suitable exhaust system to the genset. Check the manufacturer's specifications and safety regulations carefully.

For more information, or to discuss your requirements with our team of experts, call us on +44 (0) 1977 657 982 or email us at enquiries@ade-power.com.

Generators Sizing a Diesel Generator

Blog published by ADE Power on August 7th, 2017