Can you run AC and DC cable in the same conduit

[sarahstaar]

I have an underground pipe that connects my house to my garage. In the pipe I have a 240V 16amp cable and I was wondering if it's okay to also use this pipe for DC cables for my solar panels?

Or should I lay a second underground pipe purely just for DC?

On the DC side of things I will have 4 strings of solar panels each running at 336V 10A.

 

[Cmiller17363]

I don't think it is allowed by code. The inspector for my system wouldn't let me run DC and AC in the same conduit (even though the AC was only when using a backup generator). I would run a second piece of conduit for the DC to avoid weird voltage issues between the AC and DC cabling.

Others may have a more informed opinion than my own.

 

[DIYrich]

In a raceway, the AC and DC can be partitioned. Something about the AC inducing current in the DC cables.
Need a second pipe for DC.

 

[Quattrohead]

I do believe you are the same Sarah that has the YouTube channel and therefore I know you are in France. They may very well have different requirements but here in the USA all DC wiring is required to be in a metal conduit or metal clad cable inside a dwelling.
They can share a conduit with AC wiring, as can data cables BUT they must be rated at the highest expected voltage in the conduit. A lot of cable in this country has an insulation rating to 600 volts, next step up is 1500 volts.

 

[SeaGal]

I do believe you are the same Sarah that has the YouTube channel and therefore I know you are in France.

another simpler clue is where her profile says "Background: I'm currently living in France... "

 

[Bob B]

When we were installing building control equipment in a commercial environment .... AC and DC could not be in the same conduit. They could be in the same cable trough .... or enclosure, but not in the same conduit.

We were supervising the electrical install to our specifications, so, I don't 100% know the code requirement. It was always part of our written spec to the electricians ... it could also be different between commercial and residential.

 

[Quattrohead]

another simpler clue is where her profile says "Background: I'm currently living in France... "

Wayyy too many creeper clicks to see that ?

 

[Quattrohead]

When we were installing building control equipment in a commercial environment .... AC and DC could not be in the same conduit. They could be in the same cable trough .... or enclosure, but not in the same conduit.

We were supervising the electrical install to our specifications, so, I don't 100% know the code requirement. It was always part of our written spec to the electricians ... it could also be different between commercial and residential.

Worthy of note, thanks.

 

[sarahstaar]

I do believe you are the same Sarah that has the YouTube channel and therefore I know you are in France. They may very well have different requirements but here in the USA all DC wiring is required to be in a metal conduit or metal clad cable inside a dwelling.
They can share a conduit with AC wiring, as can data cables BUT they must be rated at the highest expected voltage in the conduit. A lot of cable in this country has an insulation rating to 600 volts, next step up is 1500 volts.

Yes I'm the Sarah from the gridbusters YouTube channel.

 

[sarahstaar]

Thanks for all your feedback much appreciated.

I'm going to lay the 240V cable in a new underground conduit.

 

[Quattrohead]

Yes I'm the Sarah from the gridbusters YouTube channel.

Fantastic name for your channel.

 

[Balrog006]

In the US, per standard NEC, AC and DC conductors that are part of the “same system” can share space in the same enclosure. For example a wiring gutter that has solar DC going to the inverter and main AC from a switch to the inverter are part of the same system and permissible with certain conditions.

Source “Power conductors of AC and DC systems rated 600V or less can occupy the same raceway, cable, or enclosure if all conductors have an insulation voltage rating not less than the maximum circuit voltage [300.3(C)(1)].”

Now that said, the OP is not in the US and has decided wisely to separate her runs of conductors, but I cannot say what the rule there is.

 

[SeaGal]

but I cannot say what the rule there is.

IME... formula for rules is...

France < UK < USA

 

[Balrog006]

IME... formula for rules is...

France < UK < USA

Is that more strict to the left? Or more permissive?

 

[timselectric]

Is that more strict to the left? Or more permissive?

Permissive

 

[fmeili1]

Source: https://up.codes/s/general-requirements-for-wiring-methods-and-materials

(C) Conductors of Different Systems
(1) 1000 Volts, Nominal, or Less
Conductors of ac and dc circuits, rated 1000 volts, nominal, or less, shall be permitted to occupy the same equipment wiring enclosure, cable, or raceway. All conductors shall have an insulation rating equal to at least the maximum circuit voltage applied to any conductor within the enclosure, cable, or raceway.
Secondary wiring to electric-discharge lamps of 1000 volts or less, if insulated for the secondary voltage involved, shall be permitted to occupy the same luminaire, sign, or outline lighting enclosure as the branch-circuit conductors.

Informational Note No. 1: See 725.136(A) for Class 2 and Class 3 circuit conductors.

Informational Note No. 2: See 690.31(B) for photovoltaic source and output circuits.

 

[AZ Solar Junkie]

Source: https://up.codes/s/general-requirements-for-wiring-methods-and-materials

I notice that is from the Florida electrical code. When there is a difference between a state’s electrical code and the NEC, that standard do you need to follow?

 

[timselectric]

I notice that is from the Florida electrical code. When there is a difference between a state’s electrical code and the NEC, that standard do you need to follow?

The local AHJ is the only one that matters.

 

[fmeili1]

I notice that is from the Florida electrical code. When there is a difference between a state’s electrical code and the NEC, that standard do you need to follow?

I'm not sure about that. But @Balrog006 mentioned a NEC specification with max. 600V. I think all PV strings are usually below 500V (the MPPT max Voc's are usually lower) so even if the 600V requirement would be in use, it should be good.

 

[fmeili1]

The local AHJ is the only one that matters.

Thanks, good to know! Now I would like to find out if there is a similar exception for Arizona like the one for Florida.