Question 1

What gauge bus wire do I need for DCC?

Accepted Answer

Most HO layouts use 14 AWG up to about 50 ft and 12 AWG for runs up to 100 ft. 16 AWG only suffices for runs under roughly 20 ft. NMRA guidance: size the bus so the voltage drop at the farthest point is no more than 5% of booster output at maximum current.

Question 2

How often should I add feeders to a DCC layout?

Accepted Answer

The community consensus is every 3 to 6 feet (the 6-foot rule). Smaller scales with smaller rail need feeders closer than that. Never rely on rail joiners as electrical conductors — they loosen and oxidize.

Question 3

What DCC voltage drop is acceptable?

Accepted Answer

NMRA target: under 5% voltage drop at the farthest point at maximum booster current. Above 5%, expect speed inconsistency and stalls; above 8%, expect decoder glitches and unreliable short-circuit protection.

Question 4

Should the DCC bus be end-fed or center-fed?

Accepted Answer

Center-feeding cuts the worst-case run length in half — same wire, half the resistance to the farthest point. If end-fed voltage drop is borderline, center-feeding almost always solves it without upgrading wire.

Question 5

What is the DCC quarter test?

Accepted Answer

Drop a coin or metal object across the two rails at the farthest point from the booster. The booster's short-circuit protection should trip within a few seconds. If it doesn't, your bus is too thin, the run too long, or your connections too lossy.

Question 6

How thick and how long should DCC feeders be?

Accepted Answer

Most layouts use 20–22 AWG stranded feeders, kept short (6 inches to about 3 feet). Anything over 6 feet behaves like part of the bus, not a feeder. Solder feeders directly to the rail; don't trust joiner friction.

Question 7

Solid or stranded bus wire for DCC?

Accepted Answer

Electrically the difference is negligible at DCC frequencies. Stranded routes more easily around obstacles; solid strips cleaner and seats better in IDC connectors and suitcase taps. Pick on convenience.

Question 8

Does DCC track voltage equal power-supply voltage?

Accepted Answer

No. Track DCC voltage is typically about 2 V below the booster's DC rail. NMRA-recommended track voltages: 12 V for N, 14 V for HO, 18 V for O, 20 V+ for G.