Cabling through a wall

Mart_ · 4 Jan 2019

Hello all,

I wasn't sure where to post as its not an electrical question as such, but as sparkers do a lot of cabling I'm hoping someone can help.

Here's a pic of the void space directly above our kitchen.

On the other side of the brick wall is the loft space of what was a garage (now utility room and play room)

I'm running around 15 FLAT ethernet cables (not as bulky as traditional cables) as far away from the electrical cables as I can and want to pass them through the red bricks. I plan to bracket the cables on left joist above the electrical cables.

What's best to do here? core through the red brick (as circled) or carefully make a big enough hole through the cement line (as circled)

There's already space directly next to the electrical cables (which isn't very clear) but I don't want to use this.

If its of any relevance, these electrical cables feed directly into the consumer unit (in a cupboard in the play room) on the other side of the wall.

Grateful for any advice. Thanks.

AndyPRK · 4 Jan 2019

before you go the cement option, check its only 1 layer of bricks

Mart_ · 6 Jan 2019

AndyPRK said:
before you go the cement option, check its only 1 layer of bricks

Good point, I checked and it seems single skin. Thanks.

conny · 6 Jan 2019

Data cables need to be a 100mm minimum separation from mains cables.
Those circles look like they will be too close to comply.

333rocky333 · 6 Jan 2019

conny said:
Data cables need to be a 100mm minimum separation from mains cables.
Those circles look like they will be too close to comply.

What regulation does it not comply with.
Any such reg would forbid the use of compartment dado trunking.

Jackrae · 6 Jan 2019

The grey block to the left will be extremely soft. Drill as large a hole as you can through it as near to the brick as you can. If, after you've gone deep enough you haven't penetrated to the other side (ie it forms part of a corner), then dig into the hole from the other side.

bernardgreen · 7 Jan 2019

conny said:
Data cables need to be a 100mm minimum separation from mains cables.

In terms of data corruption the separation distance varies according to :-

1/ the type and format of the data
2/ the type of transmistters and receivers
3/ the type of data cable
4/ the amount and type of high frequency interference being carried by the mains cable ( from SMPS etc etc )

From a safety point of view the insulation / separation between LV ( mains ) and ELV ( data ) has to be adequate to ensure LV conductors cannot make contact with ELV conductors

conny · 7 Jan 2019

333rocky333 said:
What regulation does it not comply with.
Any such reg would forbid the use of compartment dado trunking.

I'm thinking 528.2 would apply in this circumstance.

333rocky333 · 7 Jan 2019

conny said:
I'm thinking 528.2 would apply in this circumstance.

Why, the cables are above his kitchen, your referring to a reg for underground cables.

conny · 8 Jan 2019

Surely there is still the possibility of interference, (EMC), if you don't have the separation regardless of where the cables are?

DetlefSchmitz · 8 Jan 2019

Personally, I would certainly be prepared to risk it.

bernardgreen · 9 Jan 2019

conny said:
Surely there is still the possibility of interference, (EMC),

Yes there is. but a robust data link will be tolerant of induced voltages and not be corrupted. For example an RS422 transmitter transmits a minimum of +/- 2 volts and the receiver has a sensitivity of +/- 0.2 volts. ( fully loaded system ) The normal TX voltage is +/-5 volts. The signal is the difference in voltage between the two conductors and not the absolute voltage relative to ground and /or system O volts

To corrupt a data bit on a the induced voltage has to be large enough to convert a +2 volt signal into a -0.2 volt signal ( or -2 volt to +0.2 ) and hold that induced voltage for at least 1/2 a bit time. In most cases the system is only lightly loaded and the induced voltage has to be > 5 volts before data is corrupted.

To induce a 2 volt difference between the conductors in a twisted pair cable is possible but difficult even when one is intentionally trying to disrupt the data ( as in a test laboratory ).

With a twisted pair data cable the induced voltage from cables carrying mains voltage / current will be capacitively coupled and affect both conductors in the same way and thus no differential voltage occurs. The receiver reads the data by measuring the difference in voltage between the two conductors

Much of the "fear of inter fear ance" comes from experience of problems with RS232 systems where the signal was not transmitted as a differential voltage on a balanced pair.

In RS232 the two conductors had different impedances to system 0 volts ( signal conductor~ 5,000 ohms and 0v conductor < 100 ohm ) so the induced voltage was grounded on the 0V conductor but remained high on the signal conductor

Simon35 · 9 Jan 2019

bernardgreen said:
Yes there is. but a robust data link will be tolerant of induced voltages and not be corrupted. For example an RS422 transmitter transmits a minimum of +/- 2 volts and the receiver has a sensitivity of +/- 0.2 volts. ( fully loaded system ) The normal TX voltage is +/-5 volts. The signal is the difference in voltage between the two conductors and not the absolute voltage relative to ground and /or system O volts

To corrupt a data bit on a the induced voltage has to be large enough to convert a +2 volt signal into a -0.2 volt signal ( or -2 volt to +0.2 ) and hold that induced voltage for at least 1/2 a bit time. In most cases the system is only lightly loaded and the induced voltage has to be > 5 volts before data is corrupted.

To induce a 2 volt difference between the conductors in a twisted pair cable is possible but difficult even when one is intentionally trying to disrupt the data ( as in a test laboratory ).

With a twisted pair data cable the induced voltage from cables carrying mains voltage / current will be capacitively coupled and affect both conductors in the same way and thus no differential voltage occurs. The receiver reads the data by measuring the difference in voltage between the two conductors

Much of the "fear of inter fear ance" comes from experience of problems with RS232 systems where the signal was not transmitted as a differential voltage on a balanced pair.

In RS232 the two conductors had different impedances to system 0 volts ( signal conductor~ 5,000 ohms and 0v conductor < 100 ohm ) so the induced voltage was grounded on the 0V conductor but remained high on the signal conductor

Just to emphasise Bernard's points above, I've commissioned many industrial control systems where network cables (Profibus generally, which is RS485 based) are in the same trunkings for long parallel distances as motor cables being driven from variable speed drives. Never had a problem, as long as cable screens are correctly connected, and even where unscreened motor cables are used, no issues.

Mart_ · 11 Jan 2019

Thanks for all these replies, much appreciated.

I'm thinking of passing through the joist to the right and then through the wall that way. Missing the electric cables altogether. Some more holes in the ceiling

diynot

If you need to find a tradesperson to get your job done, please try our local search below, or if you are doing it yourself you can find suppliers local to you.

Select the supplier or trade you require, enter your location to begin your search.

Are you a trade or supplier? You can create your listing free at DIYnot Local

Cabling through a wall

Similar threads