Dc and ac running alongside each other

[stratplus]

Hi all, came across some of these today. Seperately clipped, 2.5mm ac running alongside 4mm dc cables in loft clipped along joists. Trying to find regs for it in 7671 and bpec.

 

[Worcester]

One bit is in the ENA document that you sign / check as part of the commissioning:

General
"System installed to prevent mutual detrimental influence"

and also
d.c. system:

"Physical seperation of a.c. and d.c. cables"

I think the closest to the regs is: BS7671 Section 515 and 528

 

[stratplus]

Hi Worcester, thanks for the reply. Neither cables touch both are insulated and only run a small distance. Can this really cause detrimental influence? Did notice the G83 bit but there's nothing in the regs that points to a big no no. I will look at the sections you mention now.

 

[Earthstore]

Not an expert on this, but as they are both double insulated surly its not a problem?

 

[stratplus]

That's what I thought but sparks I've spoken to say no. Segregation of bands 1 and 2, from memory selv and pelv are lower voltages to the standard 230 so perhaps the same for dc with the differing voltages dependent on light.
Magnetism issue??

 

[JulianC]

Both Band 2. I wouldn't consider clipped alongside each other but not touching a problem. T/E is insulated and sheathed. DC cable is double insulated. They're physically separated. Can't see any mutual detrimental influence. Wouldn't worry about it.

 

[Gavin A]

I'd think there'd be problems with running both DC and AC down different cores of the same SWA cable, but no problem with running them clipped direct in seperate double insulated / insulated and sheathed cables. Possibly a problem if someone was using the same clips to bunch them all together or something.

As others have said, the second insulating layer classes as sufficient separation afaik, though we do generally try to give them a bit more space between them if possible.

 

[stratplus]

It's been picked up by the council. Getting mixed responses just want to be giving a confident response back.

 

[SolarCity]

Council? What has it got to do with them?

 

[stratplus]

Council property.

 

[Earthstore]

And now they start to worry about their installs...
Hell you should see some near me, and I can only see the roofs, there is at least one non conformity on every one.

Maybe they should worry more about the 2.5mm AC if that is from the inverter to supply.

Most council installs are/were done to a price, so corners were cut.....

 

[BruceB]

In reality there is unlikely to be a problem. Two issues spring to mind with a pedantic hat on. Both cables need to be rated for the highest voltage present if in the same containment or there is a possibility of touching. Normal mains cable may not be rated (600v?) as high as max dc voltage (800v?). Also long parallel runs would be vulnerable to lightning flashovers if there is a lightning risk.