Many years ago, in my quest to better understand what I was ordering when it came to electricity for my exhibit, I searched the internet to find the "dummies' guide" to power and found this gem on the Pacific Gas and Electric website: "Electricity is measured in terms of amperage, voltage, and wattage. Amperage (amps for short) is a measure of the amount of electricity used. Voltage (volts) measures the pressure, or force, of electricity. The amps multiplied by the volts gives you the wattage (watts), a measure of the work that electricity does per second. Think of it this way: Electricity flowing through a wire is like water flowing through a garden hose. The amount of water that can fit through the hose depends on the diameter of the hose (amps). The pressure of the water depends on how far open the faucet is (volts). The amount of work that can be done (watts) depends on both the amount and the pressure of the water (volts x amps = watts)."

Now that is an explanation I can understand. But understanding the basics of how electricity works probably doesn't answer all the questions you have about ordering electrical service for your exhibit. With that in mind, I'm sharing my nontechnical answers to the most common electrical-related questions I receive.

What's the basic formula to calculate how much power I need to order?
As previously mentioned, the formula for calculating power is amps (A) x volts (V) = watts (W). If you're into mind hooks, I am always able to remember it because the letters are alphabetical (A x V=W). I've also heard other people flip it and remember the equation by calling it the West Virginia formula: W=V x A.

Will my exhibit properties' power needs be rated in amps or watts?
Power for lighting fixtures is generally measured in watts. When you look at a light bulb, you'll either see a number printed on the top of the bulb or on its metal base. This number, typically accompanied by a "W," is the bulb's optimal wattage.

Power to run equipment is usually measured in amps. If you look at the back or bottom of a piece of equipment, there is frequently a plate or sticker attached that lists the amount of power required in amps.

How do I know how much power to order, and where should it be located?
These two questions go hand in hand in computing the number and size of outlets needed at each location within your booth. I start the process of determining how much power I need in an exhibit by referencing my exhibit's blueprint of the plan view (aka bird's-eye view). I create a spreadsheet listing all the various segments of my exhibit where I'll need dedicated outlets for lighting and equipment that need to be plugged in (e.g., at each kiosk I'll have two lights, a monitor, and a tablet, and at the information counter I'll only have a laptop and a lead-retrieval system). Here's how I build the spreadsheet:
➤  List the names of all the different types of equipment, lighting, and appliances that will need electrical power in your exhibit by area across the first row of the spreadsheet. Add a column to note additional plugs for unanticipated electrical requirements (such as outlets to power booth staffers' laptops or smartphones).
➤  List each of the general areas of your exhibit where power could be shared from a single outlet or power strip (e.g., each demo pedestal, reception counter, stage, closet, etc.) in the spreadsheet's column A.
➤  Determine the quantity of each type of equipment and light element needing power, and add this information to the cell on the spreadsheet where the exhibit area and type of equipment/lighting intersect.
➤  Research the amount of power necessary for each piece of exhibit equipment, light fixture, and electrical apparatus in amps or watts, and determine how many volts are required. These details are generally found on the back, bottom, or side of the object, most often on a silver label near the point where the power cord attaches to the item. Add this information to your spreadsheet.
➤  Consider the electrical load and how many items you need to plug in per outlet. Most surge protectors are only rated for 15 amps and offer six outlets. If you need more outlets for low-wattage lights or devices, you may want to consider ordering multiple smaller outlets (i.e., two 10A rather than one 20A) to ensure you have an adequate number of plugs during periods of peak demand.
➤  Total the spreadsheet to determine the power requirements in each area of your exhibit. Round up this number to the next 500W/5A outlet (i.e., 420W required = 500W/5A outlet).

How are exhibitors charged for their electrical power?
The electrical contractor will bill you for the actual electrical power you order at the pre-show discounted rate (or full price, if the order is placed after the discount deadline). Remember that electrical power is cheaper when ordered in larger quantities, so if you'll need 1,000 watts of power in one location, it will be cheaper to order one 1,000-watt outlet than two 500-watt outlets.

You will obviously be charged for any additional lighting equipment you rent during the show, along with any materials used for installing your power. In some cases you may be able to provide your own extension cord, assuming the following: It's a flat cable, is three-wire grounded, has an Underwriters Laboratories Inc. (UL) label, and features a minimum 14-gauge wire. Also, some electrical contractors add a flat percentage of the overall cost of power onto your bill for materials such as gaffer tape or electrical tape regardless of whether those items were actually used.

In terms of anticipating labor costs, the electricians' labor hours will be billed at straight time and/or overtime, depending on how many electricians are required and when your electrical power is installed and removed. Exhibitors are typically charged actual time for installation (with a one-hour minimum per electrician – they often travel in pairs) and automatically charged half of the installation time for tearing out the electrical wiring during dismantle.

Another note on the terms and conditions usually attached to your electrical order form: You only have until the end of the show to dispute your invoice. And unlike the general services contractor, the electrical contractors often do not distribute a final bill on site, so going to their service desk the last day of the show to get a copy of your electrical bill to audit is a good idea, even though it probably won't include the dismantle labor.

Do I need to bring my own power strips or surge protectors to connect multiple plugs into a single outlet?
First, you need to know that there's a difference between a power strip and a surge protector. Power strips just provide additional outlets; surge protectors protect your equipment from fluctuating power.

If you read the legalese in the fine print on the back of your electrical order forms, it will tell you that the electrical contractor is not responsible for any damage caused by fluctuating power and that you have no legal recourse if there is damage caused to your equipment by power surges, spikes, or dips (aka low power). So using surge protectors in your exhibit is an excellent idea, especially ones that offer a warranty to replace ruined equipment they failed to safeguard.

Most electrical contractors allow you to use your own surge protectors rather than rent them, but make sure they are UL rated and have three-prong plugs. These work like a circuit breaker to divert the excess voltage and alleviate damage to equipment from power surges. If you don't have your own surge protectors and don't want to buy and ship them, you can rent them from the electrical contractor. Just be certain you receive a surge protector and not a power strip. Also, don't confuse having extra sockets in a power strip or surge protector with having extra power. The average surge protector will trip at 15 amps, even if the outlet is rated at 20 amps.

Regardless of the muddle of electrical options available, there's one fact that stands out in my mind about working with trade show electricians: They are some of the nicest people I meet in the exhibiting world. Electricians realize that most exhibitors don't understand the ins and outs of what they do or even how they do it. So when in doubt about your electrical needs, call and ask before you place your order. Have your requirements ready, and be prepared to fax or e-mail a copy of your booth layout. Rest assured, show electricians have the power to help. E