Conductors carrying low voltage.

[Darius-parky]

In page 90 of Brown book (16th Edition) (sorry guys I haven't got my red book 17th Edition yet) Reg 515-01-02 reads;

515-01-02 Where equipment carrying current of different types or at different voltages is grouped in a common assembly (such as a switchboard, a cubical or a control desk or box), all the equipment belonging to any one type of current or any one voltage shall be effectively segregatde wherevr necessary to avoid mutual detrimental influence.

Now what about cables and conductors?

 

[danzor]

what do you mean?

Just run all your 230v cables together and keep all Cat5/phones etc at least 2inches away from the 230.

 

[Darius-parky]

No Danzor, this is about a Low voltage (12V) bathroom fan. Is it OK to run both T&Es feed from the Isolator to the Tranny and the load from Tranny to the fan in the same trunking

 

[rumrunner]

Good question .is the fan 12v ac or dc ?

 

[Grae79]

No Danzor, this is about a Low voltage (12V) bathroom fan. Is it OK to run both T&Es feed from the Isolator to the Tranny and the load from Tranny to the fan in the same trunking

looks like a 'no'. 528-01-02 "A band I circuit shall not be contained in the same wiring system as Band II voltage circuits..."

i reckon seperate/compartment trunking is needed.

 

[danzor]

Did something similar recently, running 3 cores for some low voltage underfloor heating. Kept them apart from mains voltage

 

[Darius-parky]

looks like a 'no'. 528-01-02 "A band I circuit shall not be contained in the same wiring system as Band II voltage circuits..."

i reckon seperate/compartment trunking is needed.

Thanks Grae that is what I was looking for.

 

[wayne]

quoting from the osg page 64;
band 1 and band two cables can be run together if they are insulated to the highest voltage present, the excepion if fire alarm cables and em lighting

 

[Darius-parky]

quoting from the osg page 64;
band 1 and band two cables can be run together if they are insulated to the highest voltage present, the excepion if fire alarm cables and em lighting

You are absolutely correct Wayne. It is in Brown Regs book as well (528-01-02 (i))

 

[Grae79]

is a strange one; the point of having the cables seperated is to prevent induced voltages, noise etc.

ensuring that both cables are insulated to the higher voltage - 230v in this case - isn't going to prevent any of this induction taking place, surely.

e.g. was installing some garden lighting and speakers this week. the speaker cable was just 2 core flex (3182Y), insulated to 230V. wouldn't dream of running it anywhere near mains cables.

 

[Darius-parky]

Perhaps that is why is best and safest to run them seperate ie in seperate trunkings. But then what is the point of refering to the regs.

Obviously I am refering to the Brown Regs (16th Edition) does any body know if this has been clarified in 17th Edition?

 

[rumrunner]

is a strange one; the point of having the cables seperated is to prevent induced voltages, noise etc.

ensuring that both cables are insulated to the higher voltage - 230v in this case - isn't going to prevent any of this induction taking place, surely.

e.g. was installing some garden lighting and speakers this week. the speaker cable was just 2 core flex (3182Y), insulated to 230V. wouldn't dream of running it anywhere near mains cables.

metal compartment trunking helps stop induction currents,plastic not so sure.

anyway darius why do they have to be different where are you locating your tranny ,seems to me they should be going off in different directions

 

[wayne]

i would say they wernt thinking about induced voltages ,more about a short between like i said thinking
induced voltages might give you noise but thats not their concern
spare cables should be earthed anyway
telecoms prefer theres to be run seperate anyway

 

[Darius-parky]

metal compartment trunking helps stop induction currents,plastic not so sure.

anyway darius why do they have to be different where are you locating your tranny ,seems to me they should be going off in different directions

Rum, this is a situation where the old fan on a NS spare too close to the bath tub in Z0 and Z1. NS spare is being removed, feed being extended to pull core isolator in Z3, from isolator to tranny which ih is fixed behind a panel in the pipes box, back to the fan.

Now one of the guys was using the same trunking to run the extended feed to isolator (230v) and the supply from tranny to the fan (12v). I just didn't think it was correct, when I mentioned it to him, his reply was, what f*** do you know. Show me a reg in the book which says I can't?

 

[dragon-av]

e.g. was installing some garden lighting and speakers this week. the speaker cable was just 2 core flex (3182Y), insulated to 230V. wouldn't dream of running it anywhere near mains cables.

Electrical regs and Audio video good practice are very often miles apart. its a bad idea to run speaker cabling in paralell with mains as the risk in audio terms is hum 50Hz is rarely an issue (not many speakers can actually get down that low) but its the harmonics at 100Hz and 200Hz etc that can cause issues. How do you guys rate speaker cabling for regs? Low voltage AC?