Safety: 28V DCC & 2 year olds

2199 Views 12 Replies 9 Participants Last post by Axel Tillmann, Jun 16, 2008

tcwave

Discussion Starter · May 12, 2008

Hi,

Is it safe to run DCC with a 28v transducer in G scale in terms of getting getting shocked? How safe is it around kids (2 year old) if they were to touch it? What saftey precuations can be taken to lessen any potential risk of shock? (installing fuses to limit current??)

Thanks for your advice.

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Torby

· #2 · May 12, 2008

RE: Safety: 28V DCC & 2 year olds

If they get across the rails, it will feel like pinpricks and they'll get off quickly. If they're wet, they'll feel a tingle. If you're worried about something failing and putting high voltage to the track, just use a GFI outlet.

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StanleyAmes

· #3 · May 12, 2008

RE: Safety: 28V DCC & 2 year olds

Some caution is advised. The max voltage for the system per the standard is 22 volts DCC (although some systems do put out 24 volts) and large scale decoders should be speced to handle 27 volts. Anything over that and you are likely to fry components.

You might also want to check the national electrical code especially if you are in a damp environment.

As you might guess I do not recommend such a high voltage from a safety perspective.

Stan Ames

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Greg Elmassian

· #4 · May 12, 2008

RE: Safety: 28V DCC & 2 year olds

Which voltage do you not recommend Stan? 24 volts or 22? I've never seen a system that sources 27 volts to the rails.

A common misconception is that the input voltage to a DCC system or booster equals the output voltage. In my experience there is a 3-4 volt loss between a DC input and the DCC output voltage (of course measured properly with an RMS meter).

Regards, Gre

p.s. I have 23 actual volts on my rails. It can "tingle" but it's "safe".

p.p.s Article 411, enacted 1996 lists 30 volts or less, with a maximum peak voltage of 42.4 volts, current from any one low voltage circuit not to exceed 25 amps.

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Curmudgeon

· #5 · May 12, 2008

Posted By StanleyAmes on 05/12/2008 8:56 AM
Some caution is advised. The max voltage for the system per the standard is 22 volts DCC (although some systems do put out 24 volts) and large scale decoders should be speced to handle 27 volts. Anything over that and you are likely to fry components.
You might also want to check the national electrical code especially if you are in a damp environment.
As you might guess I do not recommend such a high voltage from a safety perspective.
Stan Ames

Gotta save that one.

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Torby

· #6 · May 12, 2008

RE: Safety: 28V DCC & 2 year olds

Regardless of what it does to your decoder, it's not going to fry your 2-year-old.

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Dan Pierce

· #7 · May 15, 2008

RE: Safety: 28V DCC & 2 year olds

Some older power packs without a load would output over 30 volts. Some sound units and decoders did not like this.

The newer regulated power packs are much better and run at the rated output.

I personally would not go over 24 volts for my track powered line and that is the TE input voltage, approx. 22 can go to the track.

PS, I have a light bulb for mosfet drain on all my loops. This light bulb is powered from the track separate form the feeders and tells me if I have a supply issue vs engine problem.

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Greg Elmassian

· #8 · May 15, 2008

RE: Safety: 28V DCC & 2 year olds

Dan, the originator of the thread indicated DCC, so I've limited my comments to DCC.

I think you will find that ALL DCC boosters have a regulated/limited output, and I have not found a US-made DCC booster that puts out over 22 volts, and most have a lower maxiumum.

So even with a higher input voltage, the output to the rails would be under 22 volts.

Regards, Greg

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Road Foreman

· #9 · May 15, 2008

Guys,

The NMRA specs for large scale decoders is they work from 18 volts minimum & up to 27 volts maxium.. The 22 volts is probably for safety, so if a booster puts out more than the spec the decoders will live, plus the Massoth & LGB MTS systems put out 24 volts.. The low voltage specs in the USA are 50 volts, a little above the telephone line voltage of 48 volts.. Tom is right, if worried plug it in to a GFCI, if you are outdoors it has to be plugged in to a GFCI..

BulletBob

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· #10 · Jun 9, 2008

22 volts is about all that is necessary on the rails for prototypical speeds. Besides, even 22 volts will remind you that it's here if you lay your arm on energized rails. It also keeps the neighbor's cat off the tracks....

- gws

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MarkLewis

· #11 · Jun 9, 2008

When we exhibit our modules at shows, the COGRS always displays a sign that reads: CAUTION!! 22,000 mV on tracks at all times, Do not touch the rails." This really helps to get parents to keep their kids back.

Mark

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Torby

· #12 · Jun 9, 2008

Hehe I remember an old electronic hobbiest's poster:
CAUTION
20,000 ohms

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Axel Tillmann

· #13 · Jun 16, 2008

I just saw this post. I am using Zimo and on my layoput I use a 28V AC transfoer (max input voltage for Zimo) and I can adjust the output to any voltage I want. The good news abolut 28V AC transformers, if they go into the knees, which they do the higher the utilization I still have 24V under full usage.

Of course tha talso means I have 28V if nothing but my siwtch decoders are connected.

As far as ZIP goes, yes when I level my track and forget about the power on the track, it wakes me up right away again

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