ADS

[smithjim0001]

I would really appriciate the individuals understanding of Automatic disconnection of supply if possible.

Basically what does it mean to you in your own words and how is it acheived.

Not a competition or anything nobody wins a prize but would like to see answers.

Thanks Men

 

[Lenny07]

My understanding of it is that if a fault exists in a circuit then the appropriate cpc will allow the high fault current to trip the protective device. Maybe it is only a very basic understanding but id like to read other posts. Im a house basher and know 1 has ever sat me down and told ne the raesons why and how ads is achieved, im almost sure i wasnt taught it at college. whats your view? it helps me learn as im in the trade of wire that house as fast as u can and dont ask questions, its how i was taught during my apprentership which hinders me now as i have to ask what other people probably think r silly questions.

 

[smithjim0001]

My understanding is no different,

By earthing a metal componant such as a cooker in the event that a live wire touched the outer casing thus causing it to become live a fault current would cause the protective device to operate

But like you i would like to get other opinions.

 

[septiclecky]

The only difference I can see with ADS and EEBADS is that the Earthed Equipotential Bonding has been dropped with Automatic Disconnection Of Supply staying.

 

[Cirrus]

^^^^^^^ In total agreement with Septic

 

[spinlondon]

ADS works by allowing a high a fault current to flow, which in turn will cause the protective device to operate.

The higher the current flow, the faster the protective device will operate.

 

[sprocketflup]

ADS works by allowing a high a fault current to flow, which in turn will cause the protective device to operate.The higher the current flow, the faster the protective device will operate.

..and without that high fault current stampeding down the circuit the protective device wont do its job and is thus rendered useless.

Ive wondered about the wisdom of having main bonds cable sizes as "over 50% of the tails size" i.e. 25mm tails - 16mm bond. Surely they should be the same size?

 

[ADS]

..and without that high fault current stampeding down the circuit the protective device wont do its job and is thus rendered useless.

30mA RCD?? ; \

 

[sprocketflup]

30mA RCD?? ; \

smarty pants :B

 

[Sidewinder]

Ahh, an RCD does not provide ADS per se, it is "Additional Protection"

 

[Chr!s]

Ahh, an RCD does not provide ADS per se, it is "Additional Protection"

ADS

i (Basic protection by) - Insulation of live parts, or barriers or enclosures.

ii (Fault protection by) - (1)Protective earthing, (2)protective equipotential bonding, (3)automatic disconnection.

(3) Automatic disconnection may be achieved by a Fuse, Circuit Breaker or RCD.

Two areas people seem to get confused with, (1) A RCD may be used for automatic disconnection, and (2) protective equipotential bonding is part of ADS.

Hope that helps

 

[Sidewinder]

OK Plumber point taken.

It does not help me at all actually.

I have not checked up your points.

I do not get confused between these areas, IMHO an RCD must not be relied upon for ADS alone.

An RCD will only provide disconnection in the event of a L-E or N-E fault.

As you say IF all the other requirements are in place.

 

[Chr!s]

I have not checked up your points.

Please do

It does not help me at all actually.

I think it has a little:O

I do not get confused between these areas,

Its quite alright we all get confused from time to time

IMHO an RCD must not be relied upon for ADS alone

And neither must a fuse or Mcb

An RCD will only provide disconnection in the event of a L-E or N-E fault.

This is true, not sure what your point is though?

As you say IF all the other requirements are in place.

All of which are a prerequisite for ADS.

 

[Sidewinder]

Plumber,

I fail to see your point in you quoting my post above.

I have no issues with the regs in this area or any other.

I know my limits, it is a requirement of my professional registration that I know my limits & that I work to them.

I am also bound to undertake annual formal CPD to retain this registration, this is not a requirement for electricians and plumbers.

I do not post in formal technical language on the forum, the same as I do not post in formal legal terminology, there would be no point.

I will also phrase my wording to suit my audience where this is appropriate.

Thus my posts will often not be formally technically correct, however, I will have worded them in a manner I see fit in response to the points in the thread.

Often when I discuss lamps with my customers I will refer to them as bulbs, as this is the language they understand, I may well explain the correct term, however, this would be wasted on many.

As an example yesterday I was discussing an issue with low voltage light fittings with my neighbour, I had to refer to the lamps as bulbs and change several other technically correct terms because he did not understand my terminology.

After all he is only a plumber.

That is the truth by the way not a wind up.

 

[Sidewinder]

Can't do 2 whole bottles!

Especially red!

 

[Larnacaman]

SideWinder, your right, RCDS are, and should be considered as ''Additional protection''

I wonder how we ever got on before RCDs and there derivatives......!!!!

I'm going on to my 5th Reg's edition now, and it just amazes me how some of you younger sparks out there, consider these devices. Not your fault i know, but how you have been brought up, by taking the Reg's to the very last word.

The fuse and the MCB, and a good earthing installation/system.....ARE the main source of protection to a circuit. Sized correctly the fuse and the MCB will disconnect that circuit with out any additional means, and have been doing so since time in memorial.

Like it or not, an RCD or any similar devices, are ADDITIONAL protection, and only required in certain circumstances. Unfortunately these devices are being relied on in too many areas, where there additional protection is taken for granted, to the detriment of having an solid/good earthing system....

An RCD, is not a ''prerequisite'' in general terms for ADS, except in specific circumstances....

Nothing wrong with RCD devices at all, just don't rely on them as a plaster for not having the basics right. Use them for what they were designed for, Additional protection where needed, and you won't go far wrong!!!

 

[spinlondon]

Additional protection can be provided with the use of a 30mA RCD, however as Plumber has pointed out, RCDs can and have for some time been used to provide fault protection.

Specifically in TT systems.

 

[Larnacaman]

Exactly my point!!!

 

[Sidewinder]

Spin,

Just because this has been done it does not make it good engineering.

The good engineering practice way would be to engineer the circuit to provide ADS without the RCD, if possible, then fit the RCD as required to provide additional protection.

Remember 7671 is minimum compliance.

By design RCD's are more prone to failure to disconnect than fuses and MCB's, & MCCB's.

 

[Chr!s]

SideWinder, your right, RCDS are, and should be considered as ''Additional protection''

No they shouldn't, do you use a RCD for ADS in a TT?

I wonder how we ever got on before RCDs and there derivatives......!!!!

People were probably saying the same when MCBS first arrived, technology moves on.

I'm going on to my 5th Reg's edition now, and it just amazes me how some of you younger sparks out there, consider these devices. Not your fault i know, but how you have been brought up, by taking the Reg's to the very last word

Its not just young sparks, also the dnos are quite happy to put in a front end RCD in. And im happy to see sparks working to the last word of the regs, its the ones who dont who worry me.

The fuse and the MCB, and a good earthing installation/system.....ARE the main source of protection to a circuit. Sized correctly the fuse and the MCB will disconnect that circuit with out any additional means, and have been doing so since time in memorial.

ADS is for protection against electric shock, protection against overcurrent CH43 and CH 54 Earthing arrangements and Protective conductors deal with protecting the circuits.

Like it or not, an RCD or any similar devices, are ADDITIONAL protection, and only required in certain circumstances. Unfortunately these devices are being relied on in too many areas, where there additional protection is taken for granted, to the detriment of having an solid/good earthing system...

.No there not, thats just your opinion, the fact is they may be used for ADS and Earth Fault Current Protection, and thats Fact not opinion. Like it or lump it.

An RCD, is not a ''prerequisite'' in general terms for ADS, except in specific circumstances...

Its a prerquisite of ADS the same as a Fuse or MCB is.