Can an Earth leakage be used as a main switch ?

[Steven@platinum.co.za]

Hi guys, I hope you are well.

I would like to find out if the following would be considered compliant.

A CoC was recently issued on a property where there is no separate main circuit breaker on the DB board, the earth leakage is being used as both the main switch & earth leakage.

There is only one DB board on the property which is fed directly from the Eskom box on the side of the road, there is no inline circuit breaker between the Eskom box and DB board. Based on this there is no way to isolate the DB as the Eskom box is locked.

Would this be considered compliant ?

I have attached a photo of the DB board as reference.

Thanks in advance for any assistance.

[Derlyn]

Not legal.

Each conductor that forms part of the installation must be protected by an over current protective device. An earth leakage is not an overcurrent protective device.

6.7.1.3. Eskoms protective device can serve the purpose but only if eskom agrees and if the user has access to it which you have stated is not the case.

Here in my valley we use a double pole circuit breaker for the main switch, so that should there be a serious short somewhere, it will trip on the db and not in the supplier's kiosk.

I would not have issued a coc for that db.

Also very impractical in that one cannot remove the lights circuit or stove circuit from the earth leakage if you so desire.

Peace out .. Derek

[ians]

KA ratings ... now we taking a whole different can of worms.

I was involved in a dispute with regards to cable size which was impacted by the ka rating (fault level) ... 2 x 70 mm cables could not be used because the fault level was too high for the cables ... which is determined by the transformer size ... cable length ... bussbars in a DB etc etc etc ... many many factors to be considered ... it would require a new thread.

What I do see a lot are sparkies who dont have a clue and fit 2.5 ka breakers in factory environments where the DB is 5 or 10 ka rated and even has a label.

This is a topic not many electricians understand ... which shows during investigations ... not such a big deal with domestic work ... however when working in commercial and industrial sites ... it can have a huge impact on design of the supply cabling ... the DB ... the switchgear ... the bussbars and many other parts ... in most cases ... equipment is designed and installed to reduce the fault level at the DB ... the higher the fault level the bigger tha bang ... boy have I learnt the hard way when a 1500 amp breaker tripped due to a dead short ...burnt my face ... arms and clothing ... and no I wasnt wearing the correct protective clothing ... it could have been a lot worse.

When you start digging around in 3000 amp bussbars to try fit 3000 amp flexible current clamps with the power still on ... in crazy ... thats why I stopped doing it.

In short ... in our part of town ... 2.5 ka is the norm for a domestic installation ... worse case senerio it might be 5 ka at the meter ... but very unlikely ... in places were eskom supply the power directly to the property (like a farm) you would find the transformer is above the meter ... in this case you would need to consider the ka rating.

[Dave A]

And there I was thinking the question was whether the earth leakage unit can act as the main switch (disconnector). Which as it disconnects both the live and neutral in this single phase installation at the point of supply, the answer is obviously YES, the earth leakage unit can also act as the main switch disconnector.

It is not required to have a separate main switch disconnector.
The issue of overcurrent protection is another matter...

[ians]

Something else not many people know ... what we refer to as a geyser combo breaker ... which has a green and a white lever ... can be used as an isolator ... in fact in many cases a double pole circuit breaker can also be used as an isolator/overcurrent protection device ... the only reason they make a geyser combo breaker is due to the cost.

In fact a good practice would be to use a 60 amp combo breaker /isolator where the cable from the meter which has an 80 amp council breaker is fed via 16 mm cable ... it would save you fitting a 60 amp circuit breaker with a 60 amp double pole isolator.

In my opinion ... it is not good practice to use an earth leakage as a main switch ... but it is not illegal ... if you want to screw your customer for constant call fees ... fit an earth leakage as a main switch ... eventually they will catch on and dump you as their sparkie.

[Derlyn]

@Dave

Of course you are correct, an earth leakage may be used as an isolator, but only under certain conditions.

Had the db in the photo been a sub db fed from the main db through a suitable circuit breaker then it would be acceptable and I would have passed it.

In this case it is the main db and neither the earth leakage nor the jumpers feeding the circuits has overcurrent protection. The manufacturer specs state that the earth leakage must have seperate overload protection, which it hasn't got, so this particular db is not compliant.

Steven asked whether the db is compliant.

I say no.

Peace out .. Derek.

[ians]

For the record I think 10 ka is the limit for "home made DB's" ... anything panel built with a fault level over 10 KA is subject to special approval.

I am sure someone will correct me if this has changed.

When you start working in panels over 10 KA ... it is good practise to wear the correct protective clothing.

I spent many hours in induction session to prepare to work on sites like Mondi ... Alusaf ... RBM ... sugar mills etc and watched footage of explosions caused by electrical faults.

I have also witness many accidents while working on these big sites were people has been seriously injured ... lost fingers ....lost the use their hands ... and even watched a person fall to his death from the top of the Chatsworth shopping centre.

[ians]

As per the picture ... I am impressed to see someone actually fit a label ... "fed from ....." not often you see that.

In our part of the country ... it is legal to use an earth leakage unit as a main switch ... so long as it is correctly rated ... IE: if the circuit breaker in the meter box feeding the earth leakage is 60 amps or less and the earth leakage is rated to 60 amp ... it would be regarded as legal ... it just becomes a nuisance tripping issue.

By the way ... there should be be a circuit breaker in the meter box to protect the cable from the meter to the main DB.

Just looking at the picture ... it looks like someone did actually go to the site and carry out a test ...fit DB blanks and the correct labeling

Can an earth leakage be used as a main switch ... I agree with Dave ... in our part of the country .. yes.

[Derlyn]

As per the picture ... I am impressed to see someone actually fit a label ... "fed from ....." not often you see that.

In our part of the country ... it is legal to use an earth leakage unit as a main switch ... so long as it is correctly rated ... IE: if the circuit breaker in the meter box feeding the earth leakage is 60 amps or less and the earth leakage is rated to 60 amp ... it would be regarded as legal ... it just becomes a nuisance tripping issue.

By the way ... there should be be a circuit breaker in the meter box to protect the cable from the meter to the main DB.

Just looking at the picture ... it looks like someone did actually go to the site and carry out a test ...fit DB blanks and the correct labeling

Can an earth leakage be used as a main switch ... I agree with Dave ... in our part of the country .. yes.

The chances that the circuit breaker in the meter box feeding the db is 60 Amps or less is probably about 2%.
I have never seen smaller than 70 or 80 Amps. Anyway that's here in East London.

As far as I'm aware, there is only one make of earth leakage that offers both leakage current and overcurrent protection that is readily available and it's only in Samite and by CBI. They are not cheap.
The rest basically all require seperate overcurrent protection.

When I come across a main db with only an isolator as the main, I always install a 60Amp main breaker as well so that the earth leakage relay is protected. A single pole breaker in the main live is enough.

Peace out ... Derek.

[GCE]

The chances that the circuit breaker in the meter box feeding the db is 60 Amps or less is probably about 2%.

As far as I'm aware, there is only one make of earth leakage that offers both leakage current and overcurrent protection that is readily available and it's only in Samite and by CBI. They are not cheap.
The rest basically all require seperate overcurrent protection.


Peace out ... Derek.

There are other makes that have Overcurrent protection , or combined units as the reg's refer to