DC voltage NEC

Status
Not open for further replies.
J

jerryblc

Member
Hazardous Location-DC voltage.

(2) circuits (1) 110 VDC and the other 24 VDC.

each in seperate sheath, twisted shielded conductors, in rated (hazardous) flexible conduit, with glands each end.

This is for a solenoid valve with position switch.

The solenoid is 110V and the position switch is 24V.

Where does the NEC (IEC-International or others) tell someone that you can or cannot run different class voltages in the same conduit, especially DC.

I cannot find anything in the Code book that tells me not too, but I don't like this.

If you know where in the Code please share here.

Maybe this could go for some revisions in '05.

there is very little covering dc.

Jerryblc
 
Re: DC voltage NEC

maybe some dont have enough info...

Electrical Data:
Solenoid: Operating voltage 110-140 VDC
current drain: max 1amp.

Switch for open and closed position indication.
current rating , mA: 10 min, 100 max.
voltage rating, VDC: 10 min. 32 max.

this valve comes with a connector (mil type) and these are lumped together.

I did not design this, I inherited this.

so if you know of some code articles, ...

J
 
Re: DC voltage NEC

there is very little covering dc

That's because as far as the Code is concerned there is little difference between AC and DC. What applies to AC applies to your circumstances.

Look at Article 725.55. I believe that the two circuits can be run together if 725.55(D)is met.

However, you mention a hazardous location so all bets are off as to whether this is a suitable wiring method. Tell us more about the location.

-Hal
 
Re: DC voltage NEC

Thanks Hal,

I haven't looked at the one article that you mentioned, but I will.

To answer your question, this is a gas fuel solenoid, on the manifold for a turbine engine, inside the enclosure, I don't have a picture, but, the area is definetely a hazardous location, there would (will) be quite a few air changes, but I can't count on that.

This is probably a situation not usual for NEC applications, but if it passes this code then I can translate this to IEC, CENELEC...

I could see this inside a facility for power generation etc.

J
 
Re: DC voltage NEC

The fact that it is a hazardous location (assuming listed explosion-proof fittings/seals/methods are used per Article 501) should not affect the mixing of different circuits/voltages.

Note Article 725 would only apply if these are power limited circuits. These could be 600V cables pulled through a single rigid conduit with explosion-proof fittings, in which case there would be no problem code-wise. (Based on the info given).
 
Re: DC voltage NEC

... this is a gas fuel solenoid, on the manifold for a turbine engine, inside the enclosure...

If you are the manufacturer of the gas turbine the NEC doesn't necessarily apply. The NEC covers electrical systems within buildings. Equipment manufacturers can use different methods. You would seek to have the entire equipment listed by an agency such as UL which would include what you are talking about.

If this is something of your own design and you are using it to modify an already listed piece of equipment IMO you would have to have the cooperation of the original equipment manufacturer, have it tested with the equipment and have the equipment re-listed or at least have your device listed for use with each particular piece of equipment you want it to be used with.

Either way you need to comply with the requirements of the listing agency not the NEC.


-Hal
 
Status
Not open for further replies.
Top