Hey all,

So I believe it is good practice to have AC & DC cables in separate trunking / conduit.

My question is why? Is it in fear of the DC cable inducing DC current into the AC cable?

 

My next question is how much of an issue / concern is this for us with battery cables sharing the same trunking as the AC cables?

From what I have seen with most installs, it sometimes seem unavoidable that the DC and AC cables will cross at some point on their journey to the inverter inputs.

Not 100% sure what the safety concerns are - but it is a legal requirement for a CoC, so you will never get a CoC unless you separate them.

24 minutes ago, PsyCLown said:

Hey all,

So I believe it is good practice to have AC & DC cables in separate trunking / conduit.

My question is why? Is it in fear of the DC cable inducing DC current into the AC cable?

 

My next question is how much of an issue / concern is this for us with battery cables sharing the same trunking as the AC cables?

From what I have seen with most installs, it sometimes seem unavoidable that the DC and AC cables will cross at some point on their journey to the inverter inputs.

Problems around induced signals are only present in comms and voice/sound signals when in the same conduit as AC or DC.

In any large substation one will find breaking of the legal requirement in most cables. On a large power transformer there are about 80-90 cables from 2 to 37 core. If AC and DC had to be split one might have to use 130 cables. No unwanted signals that I know of otherwise the practice would have been stopped decades ago. Further all the cables would run in the same cable trenches between the yard and the control room. Trenches house all cables to control rooms and all cables are lying on top of each other unlike on racking systems where one can have them neatly tied and split. Makes one think about the legal requirements and practice and reasons. 

On 2023/08/04 at 4:46 PM, JustinSchoeman said:

Not 100% sure what the safety concerns are - but it is a legal requirement for a CoC, so you will never get a CoC unless you separate them.

So how does one split them as sometimes the position of the battery, DB board and inverter do not allow for the dc cables to not cross over the ac cables? 

 

Also in most installs it seems as if the solar cable shares a conduit with all other cables en route to the inverter? 

Edited August 8, 20233 yr by PsyCLown

51 minutes ago, PsyCLown said:

So how does one split them as sometimes the position of the battery, DB board and inverter do not allow for the dc cables to not cross over the ac cables? 

 

Also in most installs it seems as if the solar cable shares a conduit with all other cables en route to the inverter? 

You normally use trunking and you can use a separater inside the trunking. 

I belief trunking is not a conduit. 

@TaliaB can help us out. 

Edited August 8, 20233 yr by Scorp007

The regs refer to a 'wireway', and both trunking and conduits are types of wireway.

To cross cables you can get trunking partitions, or just use two different heights, and cut a slot in the bottom of the higher one to allow the lower one to pass completely through the higher one:

 

28 minutes ago, Scorp007 said:

You normally use trunking and you can use a separater inside the trunking. 

I belief trunking is not a conduit. 

@TaliaB can help us out. 

Yes trunking with seperator is legal. Trunking and wireway is the same classification. Conduit can not contain ac and dc wiring as electrical seperation can not be achieved. One can achieve isolation between AC & DC cables using trunking that has an internal divider to separate AC and DC cabling. This does not provide any EMI/noise protection between cables but does give suitable electrical isolation/separation. One must however plan the installation so that the AC and DC sides remain separated along the full route.

 

Some use sprague to separate the AC from DC within one trunking. 

 

Easy to cut length wise and push the cables in. Then cable tie. Wonder if it being cut affects anything. 

Edited August 8, 20233 yr by abd7

On 2023/08/08 at 8:52 PM, abd7 said:

Some use sprague to separate the AC from DC within one trunking. 

 

Easy to cut length wise and push the cables in. Then cable tie. Wonder if it being cut affects anything. 

Then this seems like an easy way out, simply run all DC cables inside sprague in the trunking, lol

 

@TaliaB Would one be allowed to cut it and cable tie it and pass COC or would one need to keep the sprague uncut?

 

Also where does one find the internal dividers for trunking? I googled and could only find overseas.

On 2023/08/10 at 10:00 AM, PsyCLown said:

Would one be allowed to cut it and cable tie it and pass COC or would one need to keep the sprague⁸ uncut?

@PsyCLown look when it comes to splitting of ac/dc cables it is a bit of a grey area within sans10142 personally i will issue a coc if they are in the same trunking BUT the dc cable rating needs to be higher or the same rating as the ac when running in the trunking together. The diffrence between battery cable and welding cable is the voltage rating. The battery cable has normally a voltage rating of 60V, whereas the welding cable has a rating of 600V. 

I import my trunking deviders from Rs online but using double truncking achieves the same result just use sprague where the wires cross