Lamp post temp supply circuit arrangement

[gazdkw82]

We have a square at my works that is used for events and functions. This square has 3 lamp posts around it that have supply's via a commando style outlet which are all supplied from a local DB on a 32 RCBO.

Our technician has highlighted there is no discrimination between the 32A RCBO on the DB and the 32A RCBO that is protecting 2 circuits inbuilt within a small portable board that has 4 MK masterseal sockets. These temp boards are wired in 4mm artic flex.

so, the suggestion is to replace the 32A RCBO in the main DB with a 32A mcb which will mean there is no chance either rcbo could trip (temp board and main DB)

Within this, the current commando style sockets within the lamp posts will be changed to a 4way micro fragma board which will supply 2 circuits. 1 for wifi router on the top of the lamp post and 1 for the temp board supply.

i have been told the artic flex will also be changed to 4mm HO7RNF cable.

My questions are this.

* Does the HO7RNF cable require rcd protection?
* Will a minor works be required Everytime a temp board is made off within the wiska JB boxes using wago connectors?
* Does anyone have a better suggestion for the design of this type of arrangement?

 

[gazdkw82]

Photos attached to help

 

[gazdkw82]

Anyone able to help? Thanks

 

[westward10]

You want me to move this to the open forum you will hopefully get some responses.

 

[Richard Burns]

The lighting circuit part, being non domestic, should not require RCD protection unless the cables are going inside walls!
Therefore there should be no requirement to RCD protect the cable itself.
H07RNF is a better cable than Arctic flex.
Having 30mA RCD protection already in place does increase safety for persons and makes it hard to say you have not made the installation any less safe after the change but that is being pedantic; there are no requirements to have this protection.
Protecting the sockets with 32A RCBOs and the main board with 32A MCB also does not select for the RCBO on a L N short circuit fault as either one could still go.
I would suggest that suing wago connectors is not the most straightforward way of connection the board and using a commando socket seems easier or if space is a problem then a click flow, powerCon or IP68 tube plug and socket connection (assuming the design current is 20A not 32A).
making wiring connections to a temporary board for testing purposes may not need a minor works certificate but if it is for another purpose then theoretically it would need a certificate as you are making a change to a circuit. In practice this would not be a viable plan to put in a procedure as it would not get done properly in most cases so plugging in is better. (Though of course the temp board should be regularly tested for safety).

 

[davesparks]

Each time a temporary supply for an event is connected insoection and testing should be carried out and a BS7909 certificate completed for it.

A 32A socket outlet would be better than a wiska box with wagos. Knowing the way these things get abused by people working small events the wiska box will get abused, the lid will go missing and strain relief will never get used.
A socket outlet is much easier and safer to connect to for all concerned.
Personally when doing power distribution for events I prefer the supply not to have RCD protection as all of our distribution kit has seperate 30mA rcd for all outlets to minimise disruption whne faults occur.

 

[gazdkw82]

The lighting circuit part, being non domestic, should not require RCD protection unless the cables are going inside walls!
Therefore there should be no requirement to RCD protect the cable itself.
H07RNF is a better cable than Arctic flex.
Having 30mA RCD protection already in place does increase safety for persons and makes it hard to say you have not made the installation any less safe after the change but that is being pedantic; there are no requirements to have this protection.
Protecting the sockets with 32A RCBOs and the main board with 32A MCB also does not select for the RCBO on a L N short circuit fault as either one could still go.
I would suggest that suing wago connectors is not the most straightforward way of connection the board and using a commando socket seems easier or if space is a problem then a click flow, powerCon or IP68 tube plug and socket connection (assuming the design current is 20A not 32A).
making wiring connections to a temporary board for testing purposes may not need a minor works certificate but if it is for another purpose then theoretically it would need a certificate as you are making a change to a circuit. In practice this would not be a viable plan to put in a procedure as it would not get done properly in most cases so plugging in is better. (Though of course the temp board should be regularly tested for safety).

Doesn't a socket outlet upto 32A require RCD protection?

 

[Richard Burns]

You are correct; I was originally not aiming for the commando socket but the other options but having just read the definition of socket outlet these other options would also be considered socket outlets and so require 30aA RCD protection.
This means that whenever I fitted click flow connectors to lighting circuits (pre domestic lighting RCD requirement) I should have been RCDing the circuit and presumably the same for klik ceiling roses and a whole host of other items that have removable fixed wiring connections as well!
In practice I would agree with davesparks that the system needs to be foolproof and robust. However I cannot think of a solution that does not involve the definition of a socket outlet, it would have to be something to do with the "intended to be installed with the fixed wiring".

 

[davesparks]

This means that whenever I fitted click flow connectors to lighting circuits (pre domestic lighting RCD requirement) I should have been RCDing the circuit and presumably the same for klik ceiling roses and a whole host of other items that have removable fixed wiring connections as well!

I think there exceptions, or there used to be, for devices for connecting luminaries and luminaire supporting couplers.

 

[Lister1987]

Might be worth speaking to @TonyMarshall on here (unsure if he has access here) as he does event power so would be a good starting point, just based on his area of work.