EZ Q&A
We asked Sean Schlobom of EZ Wiring to clear up some commonly asked questions regarding wiring, as well as to give us a couple of important dos and don'ts. Here's what he had to say:

R&C
Bad grounds are probably high on the list of causes of wiring faults. What can be done to ensure a good ground, and if I'm building a 'glass car, what's the best way to get a good ground throughout the vehicle?

EZ
You need a good clean connection for a good ground. Make sure the metal is not painted where you're connecting the ground. In a 'glass car, to ensure a good ground throughout the vehicle, use a ground bus (a terminal block wired directly to the chassis) at the front of the vehicle, one for the interior and another at the rear. All grounds can be fed into these busses, knowing they have a good connection to the frame.

R&C
When are relays needed?

EZ
They're required any time a higher amperage component runs continuously, such as Halogen headlights, electric fan, horn or fuel pumps. A relay allows a device to draw power right from the battery.

R&C
What is a fusible link, and when is it preferable to use one over a Maxi fuse?

EZ
A fusible link protects the fuse panel, and protects a wire two gauges larger than itself. For instance in an EZ Wiring kit, a 10-gauge wire is protected by a 14-gauge fusible link. In my opinion it's better than a Maxi fuse as it's hard to determine what size fuse to use, and fuses don't react quickly enough. When a system is loaded to above capacity a fusible link will burn off and protect the fuse panel.

R&C
How does length of wire affect gauge size, or is resistance negligible in the length of wire in a car? I know your kits come ready to fit so this isn't relevant but how do you determine what gauge wire to use for specific amperages?

EZ
Today's wire is better than that available in the past. With cross link polyethylene wire such as used by most aftermarket harness manufacturers, we can use a smaller gauge wire than we did previously. I'd always recommend checking with the manufacturer of a component or device to determine what gauge wire to use, Resistance is pretty negligible in the lengths of wires used in the average car, but the longer the distance, the larger the gauge wire should be used.

R&C
How many circuits do I really need if I'm building a bare-bones traditional highboy? (no radio, electric fan, etc.)

EZ
A 12-circuit harness will be more than enough for a basic hot rod.

R&C
Why do my lights seem to dim or get bright depending on the engine rpm?

EZ
If the lights are dim, I'd first check for a bad ground at the light, but fluctuating brightness is usually caused by an inefficient alternator. You may need the next size larger, as the charging system is working its hardest at engine idle speed. The most common size alternator we find on hot rods that use a number of electrical systems like electric windows and fans is an 80-100amp version.