DCC Circuit Protectors and the NCE CP6

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Hello all, let me see if I can take a long story and make it shorter-- HO 13' x 18' layout, DCC using NCE's Powercab, roughly 200' of code 83 track. I recently came to the realization that this is now a "temporary" layout, as I will (probably) be moving in the next couple years. Thus, my plan is to use the next year or so to learn some more construction techniques for the next layout, but not go overboard with features that will have to be disassembled in the near future.

The current layout is on a temporary power setup; my next step is to put in and learn how to use a more robust power network. To those ends, I recently picked up an NCE SB5 booster. The plan here is to learn how to wire power districts and use the booster. I'm aiming for 4 power districts (2 mainline, 1 yard, 1 industry loop and sidings). My questions are related to the circuit protection for such a setup. On my next layout, I'll probably go with circuit breakers, but for this one, I'm leaning towards something like the CP6 circuit protector (mostly for cost purposes, I can use just one CP6 versus a breaker for each district). I have a somewhat basic understanding of electricity.

The CP6 uses 1 amp bulbs for each output as protectors. My understanding is that if there is a short, or current approaches 1 amp, the bulb will light, in essence limiting current to 1 amp and converting the rest to heat and light (yes?). So--

1) I mostly run locos with sound, which I understand average about 1/2 amp draw. Does this mean that with a 1 amp bulb, you are basically limited to running 2 sound locos per district? What happens if you run locomotives that draw total amperage over 1 amp? I'm curious because I do sometimes run trains with 3 sound locos.

2) I've read you can increase the amp limit by either installing higher amp bulbs, or by wiring more than one bulb to a power district. On that second option, how would that be done with something like the CP6? It has one input and six outputs-- if you wanted two bulbs on a district, would you connect two outputs together, and run that to the desired district? Would that now give you a 2 amp limit (assuming two 1 amp bulbs)?


Thanks in advance all,


Section Hand
Eric: Your NCE PowerCab starter system has internal protection which will self destruct if no other short circuit protection like the CP6 is provided. Yes, you can wire two CP6 lamps together to increase the amperage protection to two amps, but remember that your alone PowerCab system has an two amp total output no matter how many inputs are connected to one output on the CP6.

The NCE websiet has the manual for the CP6.

I'm not an expert with NCE systems and but others on the Forum may add to this thread, but....

I use a Digitrax DCC system and I'll share my experiences with you about my DCC layout and short circuits. I have a layout that takes up 2/3's of 12 x 16 foot room and has a mainline, passing siding, two yards, a reverse loop, an interchange which could be considered as a yard and spur tracks. I used Atlas Code 83 track, Atlas Custom Line Turnouts and have well over 200 feet of track. One single 5 amp power supply runs the layout without any power districts or power boosters. I have a Tony's Exchange "Ramp Meter" built into my system and it measures voltage supplied to the track and amperage draw.

My DCC locomotives, those with sound and pulling a train of comprised of eight cars (one a track cleaner) pulls under .35 amps. Mean while I have DCC locomotives with sound and lights on idling on various tracks and their amperage draw is minor and I never seen the total amp draw approach an amp. I have also run a train while do switching in a yard and keep the amps below a single amp. Never had a short circuit or ran a locomotive against a set turnout which caused a short circuit, but they do happen.

I doubt that you being a lone operator that you will ever run more than two or three trains tops on your layout.

The main advantage of power districts is to prevent a short from shutting down an entire layout or to add boosters when more operating power is needed. Districts are helpful for a club or large home layout since one short without power districts could shut down an entire layout and this would be embarrassing or at the least an inconvenience. By having power districts only the district with the short would be affected and the rest of the layout still be operating. I will be expanding my layout this winter to include a complex freight yard and the addition will be completely connected to the original layout without it being a power district or use a booster since the 5 amps the system provides is sufficient for the layout and my needs. I see no need for power districts.

Sometimes I think the need for power districts and using power beyond 5 amps is overkill for the average DCC layout.

My advise to you would be to construct your temporary layout and experiment with the system running a number of locomotive, trains of various lengths and some locomotives standing idle. Work and enjoy DCC slowly and you can always add power districts at a later date to an existing layout. If I remember correctly, some NCE DCC system's will tell you the track power and amps.

Please don't over complicate your DCC system. Track power feeders and soldered rail joiners are likely more important for proper operation than any other thing you may want to consider beyond the CP6. Use the SB5 only if you find you need the additional power at a later date.

Enjoy your DCC system.

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