Aquarium lighting earthing

[reds42]

I’m currently upgrading the lighting unit for an aquarium by swapping the original T8 fluorescent tubes to T5 versions and changing the electronic ballast.

On dismantling the unit I realised that the existing metal cased ballast has an earth connection which is not being used. I assume that as the unit is sealed to make it waterproof, made of plastic, and has no exterior metal parts it is not necessary for it to be earthed?

My question is whether it would be safer if I were to connect the earth on the new ballast which is also metal cased?

Whilst the unit is supposed to be waterproof, I gather it is not unheard of for some water to find its way into this type of unit causing them to fail. The circuit the light unit is plugged into is protected by a 30mA RCBO which should provide some protection from shocks if this were to happen.

However in its existing configuration if water gets into the unit it would surely not cause the RCBO to trip as there is no alternative return path for the current (unless your receiving a shock by touching it!)? If that condition was to occur then the unit could potentially be in a dangerous state where it may be wet and live to the touch.

By connecting the earth on the ballast in the unit surely it would make it safer? If water was to find its way into the unit there would be a chance the RCBO could be tripped by current running to earth if the ballast got wet.

So opinions welcome..... Would connecting an earth make it safer or not?

 

[EFLImpudence]

If it has an earth terminal then, presumably, it should be earthed.

The purpose of a CPC (circuit protective conductor - earth) is to cause the MCB/fuse to disconnect the supply should the body/casing become live.
An RCD will not do this.

You seem to understand the principles of RCDs but they do not prevent shocks but limit the duration should anyone touch a live part so it is better if the supply is disconnected by the CPC and MCB/fuse before this happens.

 

[bernardgreen]

So opinions welcome..... Would connecting an earth make it safer or not?

Yes it would.
Some years ago an un-earthed lamp fell into an aquarium tank in a pet shop. Nothing tripped as the water was isolated from earth by the glass tank.

 

[reds42]

So opinions welcome..... Would connecting an earth make it safer or not?

Yes it would.
Some years ago an un-earthed lamp fell into an aquarium tank in a pet shop. Nothing tripped as the water was isolated from earth by the glass tank.

Thats exactly the sort of situation I was envisaging and wanted to prevent if possible.

I’m bemused as to why the manufacturer that built the unit didn't bother to connect the earth on the ballast. Maybe it’s just a case of penny pinching to keep manufacturing costs down by only having to use a two core cable as opposed to three to supply it.

Just want to be sure there isn’t some reason I had overlooked that may mean its was safer for the earth connection on the ballast not to be connected.

 

[Spark123]

It is probably inside a class 2 enclosure.
I don't think the normal type of ballast is meant to be anywhere near water, moisture or where it can be dropped into the tank as there's risk of electric shock. They certainly aren't water proof!
Manufacturers instructions will specify where it is suitable.

 

[reds42]

It is probably inside a class 2 enclosure.
I don't think the normal type of ballast is meant to be anywhere near water, moisture or where it can be dropped into the tank as there's risk of electric shock. They certainly aren't water proof!
Manufacturers instructions will specify where it is suitable.

I believe it is a class 2 enclosure. The case is all plastic and is sealed to keep water out from where a standard fluorescent ballast is mounted.

It is a combined lid and lighting unit from the same manufacturer as the tank so designed for the environment its used in.

There are instances however where the sealing of this type unit has failed leading to water ingress to the electronics, and I was wondering if it was possible to improve the safety by connecting the ballast to earth for this possible situation.