Grounding a cellular antenna in attic

[ConfusedCheese]

I wish to install a small LTE antenna/router (https://mikrotik.com/product/atl18) in my attic to get a more stable signal. The device requires power via POE which will be fed from a 12v injector in the house. I was planning to mount the device via a small adjustable pole mount to the boarded attic.

The device has a small ground/earth terminal which they state needs to be connected, but would this be required when installing in the attic and not outside on a pole? If so, what would be a suitable grounding point to look for?

 

[darkknight]

Don't worry about the ground point. You can go ahead an install it without connecting it.
It is more for lightning protection, although not very good lightning protection.

We tend to install the lightning arrestors inline with the ethernet cable when installing on external poles.

 

[feynman]

Depending on the type of aerial it has, a good ground/earth might help reception. I would earth to a nearby copper water pipe if you have one, unless there is another good earth source.

 

[ConfusedCheese]

thanks both for the replies. There are no copper water pipes nearby in the attic. It’s a new(ish) build with a combi boiler so everything is fed from below.

We do have some sockets spurred off the lighting circuit (3amp fused) that are not far away… would that be a reasonable earth point to see if it improves signal?

 

[SUNRAY]

thanks both for the replies. There are no copper water pipes nearby in the attic. It’s a new(ish) build with a combi boiler so everything is fed from below.

We do have some sockets spurred off the lighting circuit (3amp fused) that are not far away… would that be a reasonable earth point to see if it improves signal?

No don't ground it to the electrics, as has been said; it is unlikely to make any difference.

Such aerials are unlikely to require an earth for signal strength purposes.

 

[ericmark]

I have no idea of type of aerial being used, unlikely at such a high frequancy it needs an earth, outside any earth would attract a lighting strike, so where possible earths are to be avoided.

As to tripping the lights, although true that a 3 amp fuse will not help, neither will putting multi final circuits on the same RCD, which presents far more risk to loss of lights than the aerial amplifier.

Both to my mind are wrong, but no point changing the circuit supplied from, if multi circuits supplied from same RCD, and looking at a few hundred pound in many cases to change to RCBO, so unless tripping, often not worth changing.

 

[JohnW2]

As to tripping the lights, although true that a 3 amp fuse will not help, neither will putting multi final circuits on the same RCD, which presents far more risk to loss of lights ...

As I always write, 'experiences vary'. In over 35 years of living with "multi-final circuits on the same RCD" (for the first good few years of which all circuits on each pohase were on the same RCD) I have very very rarely suffered 'loss of lights' for that reason ** - and, even when I have, I have not been plunged into darkness, because of the existence of emergency lighting - quite important to me, because (usually very brief) power cuts here are far more common than RCD trips (and the former won't be helped by RCBOs ).

** in fact, at least a couple of the very few 'losses of lights' due to RCD trips I can remember were due to water leaks resulting in water ingress into ceiling roses - and, in that situation, an RCBO protecting just the one circuit would obviously also have tripped and caused 'loss of lights'.

Kind Regards, John

 

[ConfusedCheese]

The sockets were installed by a local qualified electrician to power one very low powered device only and are clearly marked. They haven’t been in use for quite some time though and I have no intention to.

Is the concern there it tripping the lighting mcb? Or safety/fire reasons? Just curious.

 

[JohnD]

It's due to eccentricity and refusal to heed regulations.


Ignore it.

 

[JohnW2]

The sockets were installed by a local qualified electrician to power one very low powered device only and are clearly marked. They haven’t been in use for quite some time though and I have no intention to.

... as is very commonly done, and explicitly compliant with the Wiring Regs (even without the marking/labelling, although I personally think that is very sensible)

Is the concern there it tripping the lighting mcb?

That is apparently his concern, and he has spent the last few years driving us all mad by telling everyone about that. He appears to know a lot of people who plug high-powered vacuum cleaners into such sockets in lofts

Or safety/fire reasons? Just curious.

See above. Not a safety or fire problem at al .... just 'him'.

Kind Regards, John

 

[FrodoOne]

I wish to install a small LTE antenna/router (https://mikrotik.com/product/atl18) in my attic to get a more stable signal. The device requires power via POE which will be fed from a 12v injector in the house. I was planning to mount the device via a small adjustable pole mount to the boarded attic.

The device has a small ground/earth terminal which they state needs to be connected, but would this be required when installing in the attic and not outside on a pole? If so, what would be a suitable grounding point to look for?

Yes. Provide a "System Earth" - via the closest available "Earth" connection.

Many persons, (including Electricians) may not understand the difference between "System Earthing" and "Equipment Earthing"

System earthing​

(https://en.wikipedia.org/wiki/Earthing_system )

System earthing serves a purpose of electrical safety throughout the system that is not caused by an electrical fault.
Its main purpose is to prevent static buildup and to protect against power surges caused by nearby lightning strikes or switching.

System earthing also allows for equipotential bonding to all metalworks to prevent potential differences between them.

 

[JohnW2]

Many persons, (including Electricians) may not understand the difference between "System Earthing" and "Equipment Earthing"

System earthing serves a purpose of electrical safety throughout the system that is not caused by an electrical fault.
Its main purpose is to prevent static buildup....

We don't really have such a concept in the UK - and nor am I really sure why one would be very concerned about "static buildup"

.... and to protect against power surges caused by nearby lightning strikes or switching.......

A 'lightning arrester' or SPD needs an earth connection, but I don't see that earthing the rest of the 'system' has any relevance to lightning (in some situations, I imagine that it could actually make things worse)

.... System earthing also allows for equipotential bonding to all metalworks to prevent potential differences between them.

We do have a requirement in UK that all touchable 'conductive parts' be equipotential (if not 'electrically 'floating'). However, that only applies to what we call 'extraneous conductive parts' (conductors, such as metal utility supply pipes which enter the property from outside, and may introduce 'true earth potential' {which might be different from the installation's 'earth potential'} ) - and therefore would not apply to things such as the OP has mentioned (even if it is metal, which I doubt).

In general, a good few people in the UK regard 'unnecessary earthing' of things to be undesirable, because any increase in the amount of touchable earthed metal in a property increases the risk of electric shock.

Kind Regards, John

 

[ConfusedCheese]

even if it is metal, which I doubt

This particular antenna has a completely plastic shell apart from the metal heatsink on the back for passive cooling, screws and a small metal plate under the cover by the ethernet port (where there is threaded sleeve for an M4 screw to connect an earth/ground).

I have another one of thier LTE/5G devices designed for indoor use. It has an array of 8 antennas and is powered only by a barrel plug with a plastic earth pin on the plug, so not even grounded to electrics unless there is some magic I don't understand. If nearby lightning/ESD was a concern, would this device not also be at risk also? Or does being inside shield it from both?

Thanks for all the replies, been intersting reading through. A lot of the information I've found online is US specific or more about TV aerials so its all very confusing.