New work in old bathroom

[flyingspark]

Hello Folks,

I went to look at a job today, the customer wants a shaving/vanity light installed above the sink in the bathroom. The distribution is via rewirable fuses, and not an RCD in sight.

I checked the main lighting point in the bathroom, and it hasn

 

[NozSpark]

Is it possible to wire the bathroom bits and bobs off a RCD FS on the socket circuit??

 

[kme]

My thoughts, too. Rather than seperating them, I`d be tempted to just rewire bathroom into an RCD spur. Much less bovver than an `ovver

 

[spinlondon]

Is it possible to wire the bathroom bits and bobs off a RCD FS on the socket circuit??

Wouldn't comply with the regulations.

The whole circuit requires RCD protection, which would be back to the CU.

 

[Badger]

Wouldn't comply with the regulations.The whole circuit requires RCD protection, which would be back to the CU.

incorect as far as im aware as i was under the impression only new cables neeeded rcd protection let the Wet Fish arguments start :^O :^O

 

[kme]

incorect as far as im aware as i was under the impression only new cables neeeded rcd protection let the Wet Fish arguments start :^O :^O

Sorry Spinny; I`m with Badger on this one.

But I don`t fancy an argument tonight - I`m too bloomin` tired......... :good night:

 

[spinlondon]

incorect as far as im aware as i was under the impression only new cables neeeded rcd protection let the Wet Fish arguments start :^O :^O

No you're thinking of cables concealed in walls.

Bathrooms and rooms containing showers require RCD protection to the circuit.

 

[tom1]

No you're thinking of cables concealed in walls.Bathrooms and rooms containing showers require RCD protection to the circuit.

i thought it was just your part of the circuit.

can i ask what you based it on mate. thanks

 

[NozSpark]

Spin...

I've heared that argument before and don't agree..

I would say that a circuit starts at the last "fixed" protective device.. therefore the RCD FS would be the start of that circuit!?!?!?

I know it's a bit "out there", but look at a normal CU with a submain and SUB CU!

 

[spinlondon]

i thought it was just your part of the circuit.can i ask what you based it on mate. thanks

"701.411.3.3 Aditional protection by RCDs

Additional protection shall be provided for all circuits of the location, by use of one or more RCDs having the characteristics specified in Regulation 415.1.1."

As you can see, the reference is to protecting the circuit, not some or part of the circuit.

 

[spinlondon]

Spin...I've heared that argument before and don't agree..

I would say that a circuit starts at the last "fixed" protective device.. therefore the RCD FS would be the start of that circuit!?!?!?

I know it's a bit "out there", but look at a normal CU with a submain and SUB CU!

My understanding, is that circuits start and finish at distribution boards, or Consumer units (which are a type of Distribution Board). Not from BS1363 accessories.

 

[tom1]

"701.411.3.3 Aditional protection by RCDsAdditional protection shall be provided for all circuits of the location, by use of one or more RCDs having the characteristics specified in Regulation 415.1.1."

As you can see, the reference is to protecting the circuit, not some or part of the circuit.

regulation aside, would it make any difference?

so the best way would be to put the rcd spur next to the cu and feed the whole light circuit through it?

 

[spinlondon]

The only difference it would make, would be if the FCU was placed part way along a circuit, or on a Ring Final Circuit.

Any earth faults that occur before the RCD would then be able to enter the special location bypassing the RCD.

This is one of the reasons used when people argue that all circuits should be protected when work on only one circuit has been carried out.

 

[ianmacd]

"701.411.3.3 Aditional protection by RCDsAdditional protection shall be provided for all circuits of the location, by use of one or more RCDs having the characteristics specified in Regulation 415.1.1."

As you can see, the reference is to protecting the circuit, not some or part of the circuit.

It will be protecting the whole new circuit.

As has been said many many times before, we are not the electric police and have no right to demand a whole installation is brought up to the 17th. As long as the new addition is installed to the 17th then that is enough to satisfy that requirement.

 

[ianmacd]

The only difference it would make, would be if the FCU was placed part way along a circuit, or on a Ring Final Circuit.Any earth faults that occur before the RCD would then be able to enter the special location bypassing the RCD.

This is one of the reasons used when people argue that all circuits should be protected when work on only one circuit has been carried out.

Eh? Earth is linked at the MET or CU anyway so what difference will that make? Thats why we have bonding of extraneous metal parts.

 

[spinlondon]

It will be protecting the whole new circuit.As has been said many many times before, we are not the electric police and have no right to demand a whole installation is brought up to the 17th. As long as the new addition is installed to the 17th then that is enough to satisfy that requirement.

Your posts unfortunately are still not clear.

Are you agreeing, disagreeing, stating that the new circuit will start at the FCU or something else entirely?

 

[ianmacd]

Your posts unfortunately are still not clear.Are you agreeing, disagreeing, stating that the new circuit will start at the FCU or something else entirely?

It is clear. I quoted what I responded to. A new circuit starts at a FCU.

 

[spinlondon]

Eh? Earth is linked at the MET or CU anyway so what difference will that make? Thats why we have bonding of extraneous metal parts.

I was under the impression that the point of an RCD was to prevent electricution in the event of earth faults. If you are going to place the RCD in a position where earth faults can by pass the RCD, you might as well dispense with RCD protection altogether. Any earth fault will be cleared by the bonding anyway.

 

[spinlondon]

It is clear. I quoted what I responded to. A new circuit starts at a FCU.

I suppose asking you to support that view with perhaps something from BS7671 would provoke another unclear post, or some form of insult?

 

[ianmacd]

I was under the impression that the point of an RCD was to prevent electricution in the event of earth faults. If you are going to place the RCD in a position where earth faults can by pass the RCD, you might as well dispense with RCD protection altogether. Any earth fault will be cleared by the bonding anyway.

An RCD it there to detect an imbalance in current flowing in and out. This difference could be flowing to earth but does not have to flow down a CPC. Since a CPC is never disconnected from the rest of the installation an RCD would not stop a fault for example on a lost neutral on a TN-C-S system.