Old circuit - can I replace MCBs with RCDs? | Page 2 | on ElectriciansForums

Discuss Old circuit - can I replace MCBs with RCDs? in the Electrical Wiring, Theories and Regulations area at ElectriciansForums.net

Your right but I prefer to see RCD's especially if it's my name on the cert

WHY?? This installation could be in absolutely A1 condition with excellent Zs values throughout that has, and still is giving sterling service without ever having the need for RCD's!!
 
Just a note to OP here as everyone who has answered has self corrected in their reply but you state replacing mcb's with rcd's ... if this is your understanding that and rcd can replace a mcb then you are incorrect, RCD provides earth leakage protection only and an mcb will still be required to give S/C and overload protection..... its a RCBO that is a combination of both devices...

If you are a little confused then back to the books it is, although you are correct with the bathroom and sockets for general use another regulation re' cables buried less than 50mm from the surface and dont have mechanical protection also require rcd protection thus you tend to find every houshold circuit to 17th would normally have rcd protection.
 
WHY?? This installation could be in absolutely A1 condition with excellent Zs values throughout that has, and still is giving sterling service without ever having the need for RCD's!!

I'm not doubting the installation, yes it could be as good as the day it was put in and if it's PVC that has not been tampered with then it probably is, I'm questioning the level of protection I know if disconnection times can be achieved then all should be theoretically OK but I prefer to see RCD's as fuses/breakers don't offer adequate protection in my eyes.
 
I agree with what you're saying to a point sparkyphill,

but do you not think its abit harsh telling the client that they're board needs upgrading if its in good working order ? The client - could and sometimes(all the time) do interpret electrical things wrong, he/she could feel that it has to be changed and parting with cash for a job that doesn't necessarily need doing.
 
that's the whole point. RCDs are there primarily to prevent death or injury if anyone comes into direct contact with a live part of the installation, or if an exposed conductive part should become "live" but without sufficient leakage to trip MCB/fuse. they are only installed for fault protection on TT systems where the Zeand hence.Zs is too high to give rise to a high enough fault current to trip OCPDs.
 
I agree with what you're saying to a point sparkyphill,

but do you not think its abit harsh telling the client that they're board needs upgrading if its in good working order ? The client - could and sometimes(all the time) do interpret electrical things wrong, he/she could feel that it has to be changed and parting with cash for a job that doesn't necessarily need doing.

Just to clarify I'm not in the habit of blagging or scaring customers but if I see an installation without RCD protection then I would prefer to see one, the choice is to fit a stand alone unit before the CU which at least offers protection but will cause nuisance tripping or upgrade the board to 17th edition, either one is a dam sight better than no RCD at all
 
that's the whole point. RCDs are there primarily to prevent death or injury if anyone comes into direct contact with a live part of the installation, or if an exposed conductive part should become "live" but without sufficient leakage to trip MCB/fuse. they are only installed for fault protection on TT systems where the Zeand hence.Zs is too high to give rise to a high enough fault current to trip OCPDs.

Yep and by the time the current is high enough to take out the OPCD the damage is already done
 
Just to clarify I'm not in the habit of blagging or scaring customers but if I see an installation without RCD protection then I would prefer to see one, the choice is to fit a stand alone unit before the CU which at least offers protection but will cause nuisance tripping or upgrade the board to 17th edition, either one is a dam sight better than no RCD at all

So you're telling me that if you go to a clients house because they want an extra socket or w.e you'll try come away with at least fitting a stand alone unit?

Don't get me wrong, i agree with what you're saying, and i agree that RCD protection is the best, as everyone will. Im just saying you can't really go round changing every old board you see, its just not practicable, if it tests out okay and it looks in good condition then IMO it can be left. Fair enough, if the original board looks dangerous, yes try your best to pursuade the customer to have something done about it.

Mark
 
I'm not doubting the installation, yes it could be as good as the day it was put in and if it's PVC that has not been tampered with then it probably is, I'm questioning the level of protection I know if disconnection times can be achieved then all should be theoretically OK but I prefer to see RCD's as fuses/breakers don't offer adequate protection in my eyes.

Really!! Hell, they have been doing just that, since before you were born!! RCD's although serve as a very good additional protection, are not the cover all protective device many here think they are!!

Going on what some are saying here ...a good number of us here are lucky to still be alive and kicking after all those years without an RCD in sight!! lol!!
 
Really!! Hell, they have been doing just that, since before you were born!! RCD's although serve as a very good additional protection, are not the cover all protective device many here think they are!!

Going on what some are saying here ...a good number of us here are lucky to still be alive and kicking after all those years without an RCD in sight!! lol!!

I'm amazed that you and other people on here think it's OK to leave an old installation with 3036 fuses as it's only means of protection, no doubt you have cut through a live cable with only this type of fuse backing it up ? well I and many others have and when you see the state of your pliers afterwards your glad they where insulated !!!
 
I'm amazed that you and other people on here think it's OK to leave an old installation with 3036 fuses as it's only means of protection, no doubt you have cut through a live cable with only this type of fuse backing it up ? well I and many others have and when you see the state of your pliers afterwards your glad they where insulated !!!

So you would condem a 3036 fuse board automatically then?
 
sparkyphill, we're amazed that you seem to think every 3036 board is an instant fail on an EICR.

I seriouslly don't understand how you can justify this to the customer if the board is in good working condition and tests out okay, seems scandalous too me.
 
sparkyphill, we're amazed that you seem to think every 3036 board is an instant fail on an EICR.

I seriouslly don't understand how you can justify this to the customer if the board is in good working condition and tests out okay, seems scandalous too me.

Sorry guys we will have to agree to disagree on this one, I'm not trying to get into an argument here but my opinion is that an installation with it's only means of protection being a 3036 fuse is not good enough if you feel it is that's fine but me no
 
nobody here would disagree that a CU fitted with MCB and RCD protection is a better situation than a 3036 rewireable fuse board. the question is whether that 3036 board is safe for continued use. and how far do you go in persuading the customer to upgrade. advise by all means, but don't use scaremongering tactics. that's for the wet behind the ears young sparks who don't know any better.
 
nobody here would disagree that a CU fitted with MCB and RCD protection is a better situation than a 3036 rewireable fuse board. the question is whether that 3036 board is safe for continued use. and how far do you go in persuading the customer to upgrade. advise by all means, but don't use scaremongering tactics. that's for the wet behind the ears young sparks who don't know any better.
 

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