Advice on Installation

[Thomas Connolly]

Hi Folks,

If I'm extending a lighting circuit, (adding two pendants and an outside light) from an existing pendant but the board doesn't have any protection (an old BS3036 fuse board) What's the best way to add RCD protection?

The new cable for the switches can't buried more tore than 50mm deep and I don't want to whack an RCD FCU anywhere as they are quite bulky.

What would be the best course of action to take to install this circuit so it complies with the Regs?

Thanks,
T

 

[GBDamo]

The simplest and most stress free way to do this would be to put the RCD FCU at the point you connect to the old circuit.

This would require a sensible, accessible location.

 

[GBDamo]

One of the problems with that idea, is the requirement is to provide RCD protection for the circuit, not just part of the circuit.

I think his intention was to do this at the DB.

Why would the whole circuit need RCD protection?

Surly it would only be a requirement for the addition, or have i misunderstood the requirement again?

 

[45140]

This might be what you need
https://www.screwfix.com/p/british-general-5-module-3-way-populated-garage-consumer-unit/1926g

 

[Deleted member 26818]

I think his intention was to do this at the DB.

Why would the whole circuit need RCD protection?

Surly it would only be a requirement for the addition, or have i misunderstood the requirement again?

It’s in the wording of the Regulation, same as for locations containing baths or showers.
The requirement is for the circuit to be provided RCD protection.
This is not the same as protecting cables concealed in walls or protecting items plugged into socket-outlets.

 

[Thomas Connolly]

I figured I could put the RCD FCU next to the DB?

So the existing cable that comes from the fuse to the lighting circuit, essentially, split that in two, connect the side from the fuse to the supply side of the RCD FCU and then the cable that then runs to the lights on the load side of the RCD FCU....

That way the whole circuit is protected and the new fused unit stays out of sight but would still be accessible and I don't have to tamper with the fuse board too much (aside from safe isolation and testing etc)

Again, please feel free to correct me if I'm wrong?

 

[Deleted member 26818]

I figured I could put the RCD FCU next to the DB?

So the existing cable that comes from the fuse to the lighting circuit, essentially, split that in two, connect the side from the fuse to the supply side of the RCD FCU and then the cable that then runs to the lights on the load side of the RCD FCU....

That way the whole circuit is protected and the new fused unit stays out of sight but would still be accessible and I don't have to tamper with the fuse board too much (aside from safe isolation and testing etc)

Again, please feel free to correct me if I'm wrong?

That’s what I suggested at the start, but with a stand alone RCD in an enclosure.
If you would rather install an RCD FCU, that’s up to you.

 

[GBDamo]

It’s in the wording of the Regulation, same as for locations containing baths or showers.
The requirement is for the circuit to be provided RCD protection.
This is not the same as protecting cables concealed in walls or protecting items plugged into socket-outlets.

Don't suppose you have the reg number to hand, I may have to seek advice on this one.

I change a lot of lights which are covered by a MWC as I see this as work on the circuit.If they are click or similarly connected then no certification.

If what you say is correct then any fitting change that is not on a click type connector would require RCD addition.

Now, there's money to be made there but only if it is a requirement.

 

[Deleted member 26818]

411.3.4 Additional requirements for circuits with luminaires
Within domestic (household) premises, additional protection by an RCD with a rated residual operating current not exceeding 30 mA shall be provided for AC final circuits supplying luminaires.

 

[Thomas Connolly]

@spinlondon yes sorry, I wasn't ignoring you. It was supposed to be reiteration of what you'd said but just double checking that a RDC FCU would be sufficient.

Thanks for the help and everyone else too.

 

[SparkyChick]

411.3.4 Additional requirements for circuits with luminaires
Within domestic (household) premises, additional protection by an RCD with a rated residual operating current not exceeding 30 mA shall be provided for AC final circuits supplying luminaires.

 

[BruvDunk]

Go for a new board.
Especially if you have no RCDs for everything else....

 

[GBDamo]

Had me worried there for a moment, phoned NAPIT tech help this morning to confirm their interpretation of this reg.

As the OP is adding to an existing circuit there is no requirement to retro fit RCD protection for the whole circuit only to ensure his addition has RCD protection.

So he can either run the risk of borrowed neutrals and put an RCD at the beginning of the circuit, thus protecting the whole circuit, or find a position to put in an RCD FCU at the point he extends the lighting circuit, protecting only his additional works. Both would be compliant from the advice I have had.

I'd be pushing for the latter, you can spend time confirming there are no borrowed neutrals, as going back to the customer after the event to run in a dedicated neutral would prove embarrassing, or KISS.

 

[Bobster]

Don't think an RCD FCU will cut it anymore with the passing of the 18th edition.

The BS number they are constructed under is not recognised by 7671 as offering additional protection.

Edit: This is just what I have heard, I do not yet own a copy of the 18th.

 

[SparkyChick]

@Rob is absolutely on the money.

531.3.6 RCDs for additional protection
The use of RCDs with a rated residual operating current not exceeding 30 mA is recognized as additional protection in compliance with Regulation 415.1. These RCDs shall be provided to comply with the requirements of Regulation 411.3.3.

RCDs for additional protection in AC installations shall comply with:
- BS EN 61008 series, or
- BS EN 61009 series, or
- BS EN 62423.

Where installed at the origin of a final circuit or a group of final circuits, an RCD with a rated residual current not exceeding 30 mA may provide fault protection and additional protection simultaneously.

NOTE: Consideration shall be given to the division of the installation (see Regulations 531.3.2 and 314.2).

Section 531 has been significantly revised and now stipulates the standards RCDs used for additional protection must comply with. As best as I can tell, this effectively rules out the use of any RCD socket outlets and RCD fused spurs as these generally appear to be manufactured to BS 7288.

In the 17th addition, it was sufficient for the devices to have the characteristics specified in 415.1.1 i.e. 30mA trip current and an operating time not exceeding 40ms for 5x rated trip current.

So, is this another case of manufacturers influencing the regs for their benefit?

 

[DPG]

This is the sort of thing where the regs need to be a bit clearer, especially since it is saying that something which was a compliant method before is no longer such.