Do 24v led strips need to be earthed?

[Sard]

Do 24v led strips need to be earthed? My led driver only has Live and Neutral terminals.

Thanks in advance!

 

[Harry Bloomfield]

No.

 

[ericmark]

In the main they are SELV the s stands for separated, and so should not be earthed. We also have FELV (An extra-low voltage system in which not all of the protective measures required for SELV or PELV have been applied.) and PELV (An extra-low voltage system which is not electrically separated from Earth, but which otherwise satisfies all the requirements for SELV.) so with a PELV there should be an earth.

I would say unlikely to be PELV so as @Harry Bloomfield says No. Or there would be a terminal to connect to earth.

 

[JohnW2]

..... PELV (An extra-low voltage system which is not electrically separated from Earth, but which otherwise satisfies all the requirements for SELV.) so with a PELV there should be an earth.

What benefit derives from 'earthing something which is supplied with ELV?

Kind Regards, John

 

[ericmark]

What benefit derives from 'earthing something which is supplied with ELV?

Kind Regards, John

Why there are three ELV I can only read BS7671 where SELV, PELV and FELV are defined. I would guess it is where low voltage can in some way connected to the ELV.

 

[ebee]

No LED strips do not need to be earthed - where would you earth them?
There are a lot of mains items that do not need to be earthed because they are sufficiently insulated.
Electric hand drills used to be metallic and therefore earthed, today tend to be mostly plastic insulated so usually not earthed etc etc.

quick definition (non-technical rough approx guide only/

Low voltage = mains voltage
High voltage = transmission/distribution voltages.
Extra Low Voltage = 3 variants known as SELV or PELV or FELV (SELV is separated from Earth so do not earth it)

Quick mention - Reduced Low Voltage (a UK thing really) is about 110V and centre taped earthed so about 55V from Earth reference on either of the Lives).

That is just a very basic, quick description. I have not given numbers and methods of the different voltages and situations.

 

[FrodoOne]

Do 24v led strips need to be earthed? My led driver only has Live and Neutral terminals.

Your LED "driver" has Line and Neutral input terminals which connect to the UK (Nominal) 230 V AC (50 Hz) Supply.
(The term should be "Line" - NOT "Live" - and certainly NOT "Hot".)

The output connection(s) to the LED "strips" are from an isolated/floating 24 V supply
[possibly a SMPS (Switch Mode Power Supply)] - not connected to anything else.

Although it is more than you requested, I strongly suggest that you sit down, for an hour or so, and view

After viewing and (hopefully) understanding this, you may be able to appreciate the difference between
"System Grounding/Earthing" and
"Equipment Grounding/Earthing".

The North American based Mike Holt uses the term "Ground", whereas those in the UK (and elsewhere) uses the term "Earth".

 

[ericmark]

There should be a sign on the transformer/driver/power supply like this which means it is safely isolated from the mains supply and does not require and earth, however I note the 20 volt supply for my lap top does not have it and the 20 volt supply is not earthed. It is rare for ELV to need an earth. Reduced low voltage is 55-0-55 single phase supplied and 64-0-64 three phase supplied the line to line voltage in both cases is 110 volt, 110 site supplies have no neutral so the cables should not have a blue core and the plugs and sockets should not be marked N it should be L1 and L2 but never seen a three core yellow cable without a blue core and never seen a plug without one pin marked N, we have to use common sense, and in the same way lack of the safely isolated sign does not mean it needs earthing.

 

[JohnW2]

Why there are three ELV I can only read BS7671 where SELV, PELV and FELV are defined. .....

Firstly, I think there is a risk that two aspects of "earthed" may be getting confused. The BS7671 definitions of PELV and SELV relate to whether or not the supply/system is earth-referenced - i.e whether or not one side of the supply (or some point intermediate between the two sides) is connected to earth. The question we seem to be addressing in this thread is whether components of an ELV system (e.g. exposed-conductive parts) need to be earthed as a measure to reduce the risk of electric shock - and (so long as LV is not also 'involved') #earthing' (e.g. of exposed-c-ps) is irrelevant in the case of SELV, since it is not an earth-referenced supply. With PELV, earthing of exposed-c-ps will only reduce the risk of ('small', ELV) electric shocks if the ELV supply has adequate fault protection.

I don't really understand FELV". These BS7671 definitions ....

SELV (separated extra-low voltage). An extra-low voltage system which is electrically separated from Earth and
from other systems in such a way that a single fault cannot give rise to the risk of electric shock.
PELV (protective extra-low voltage). An extra-low voltage system which is not electrically separated from Earth,
but which otherwise satisfies all the requirements for SELV.

... are straightforward enough. They are essentially the same as one another, other than that a PELV supply/system is earth-referenced, whereas SELV is not. This distinction says nothing about the need (or not) for 'protective earthing' - other than, as above, it would be useless for that purpose with SELV.

However, BS7671 also says ...

Functional extra-low voltage (FELV). An extra-low voltage system in which not all of the protective measures
required for SELV or PELV have been applied.

... and I am struggling to understand what it means, or what situations would qualify as 'FELV" by this definition. Since the definition is silent as to whether the supply is or is not earth-referenced, that seems to imply that the only way something can be "FELV" is if it is NOT "separated from other systems in such a way that a single fault cannot give rise to thee risk of electric shock" - which makes no real sense to me!

Am I missing something?

.... I would guess it is where low voltage can in some way connected to the ELV.

Well, yes, that's the nearest to an explanation which makes at least some sense, but I'm not convinced that it's necessarily a lot of sense - not the least because a comparable argument could sometimes exist with LV as well as ELV (e.g. in the case of an 'isolating transformer' with a floating output).

Kind Regards, John

 

[ericmark]

I noted when the rules on RCD use came out in 2008 it did not state for low voltage only, clearly would not work with ELV and not easy to get RLV versions, so really down to common sense, however to without seeing exactly what we have, giving advice could be dangerous, we even bond items with no power going to them like water pipes and gas pipes, so one can't simply say ELV does not need an earth.

 

[JohnW2]

I noted when the rules on RCD use came out in 2008 it did not state for low voltage only, clearly would not work with ELV ...

Why not? RCDs only know about current, and have no idea what voltages exist in the circuit. Standard RCDs would, of course, not work with DC, and a lot of ELV is DC, but, as you know, BS7671's requirements for RCD protection specifically only relate to 'AC systems'.

Kind Regards, John