[SolarFreak]

Does anyone know any where I can find texts/paragraphs covering the requirements in terms of burial depths, voltage, etc for underground cables on the DC side. I looked at section 35 of the NESC Code 2007 Handbook as well as the section 300.5 of the NEC 2008 handbook. However, I believe those only deal with AC current. I need similar information but for DC current. Anyone?

Thanks!

[tkrussell]

The NEC is for AC and DC ,when related to building wiring and service entrance to that building.

The NESC is more for the utility side, and will allow the same.

See 300.3 (C), allows both in same raceway.

I get from your name you may be involved with solar power. If so, refer to the exception at the end of 300.3 (C) 1, refers to Section 690.4 (B), that does not allow photovoltaic wiring together in same raceway as AC wiring, unless there is a partition.

So unless specifically for PV wiring use Table 300.5.

[SolarFreak]

The NEC is for AC and DC ,when related to building wiring and service entrance to that building.

The NESC is more for the utility side, and will allow the same.

See 300.3 (C), allows both in same raceway.

I get from your name you may be involved with solar power. If so, refer to the exception at the end of 300.3 (C) 1, refers to Section 690.4 (B), that does not allow photovoltaic wiring together in same raceway as AC wiring, unless there is a partition.

So unless specifically for PV wiring use Table 300.5.

Thanks tkrussell. I am actually involved in wind farm construction. My ultimate goal however is to build a solar farm back in West Africa. I'm taking baby steps right now.
Anyway, to go back to my question, when do you know whether your specs for AC only, Dc only, or both? Cause I can't read that anywhere. Furthermore, Wouldn't the requirements for the underground cables (directly buried) on the DC side of a solar system be different than the ones on the AC side? If so what are they? And what are the differences? I've been looking over the NEC and NESC book to come up with those answers but I'm afraid I can't quite pinpoint it.

Additionally, there are lots of information on underground cables that are less than 600V but I need to account for cables above 600V as well. We may end up using 1kV cables on the DC side.

[tkrussell]

See NEC Article 300 II, Over 600 volts, burial details listed in Table 300.50.

Don't get hung up on the AC and DC thing. It is still lethal voltage, no matter which, and is treated the same.

While the NEC is written for international use, and is widely used by many countries as at least a guide, best to check with the local codes in the area your project will be located.

I am sure that in most cases using the NEC will be a good guide,but never know.

[SolarFreak]

See NEC Article 300 II, Over 600 volts, burial details listed in Table 300.50.

Don't get hung up on the AC and DC thing. It is still lethal voltage, no matter which, and is treated the same.

While the NEC is written for international use, and is widely used by many countries as at least a guide, best to check with the local codes in the area your project will be located.

I am sure that in most cases using the NEC will be a good guide,but never know.

Thanks tkrussell

[KISS]

It's kind of weird that specs for electrical seem to be written as say 600 V. They never make any distinction between AC and DC. Peak to Peak AC voltages are higher than the DC voltages. 120 VAC is like 310 V peak to peak.

300 V and 600 V cables are common designations.

[SolarFreak]

It's kinda wierd that specs for electrical seem to be written as say 600 V. They never make any distiction between AC and DC. Peak to Peak AC voltages are higher than the DC voltages. 120 VAC is like 310 V peak to peak.

300 V and 600 V cables are common designations.

Like Russel said, I think what matters the most is the voltage of the cables you're working with. The AC/DC specs don't have as much influence as the voltage designation of those cables. At least, that's what I gathered from this conversation. From an electrical engineering and construction point of view, voltage matters more. At my job interview, one of the questions they asked me was what kind of voltages have I worked with before on the field? So there you go!

[KISS]

Try scientific equipment with 100 kV at 0.1 Amps and 15 KV DC at 1 A. X-ray tube power supplies and what can best be described as acellerating voltage and electron deflection systems similar to what a picture tume might have but MUCH beefier currents.