SPDs do i need to fit them?

[Ian1972]

Hi, I'm installing a new circuit in domestic dwellings for various housing associations my question is do I need to fit an SPD or would it be the responsibility of the housing association, the circuit supplies equipment in the garden I'm running a 2.5 twin and earth through the house fed from a B16 MCB or RCBO depending on the fuse board it goes to an external rotary isolator, thanks in advance for your replys

 

[SparkyChick]

Personally, if I was just installing a new circuit, I wouldn't go to the extent of installing an SPD unless it was specifically requested.

That being said, it appears you are installing circuits specified by someone else... the designer... maybe bounce the question to them?

 

[telectrix]

Boing said Zebedee.

 

[littlespark]

Running a 16A radial to an external location…. To a rotary isolator?

What the heck for?

Run to an external socket maybe.

Are the housing associations providing hot tubs now?




Possibly Air Source Heat Pump now I think of it

 

[SparkyChick]

Possibly Air Source Heat Pump now I think of it

That was exactly my thoughts.

 

[Ian1972]

Running a 16A radial to an external location…. To a rotary isolator?

What the heck for?

Run to an external socket maybe.

Are the housing associations providing hot tubs now?




Possibly Air Source Heat Pump now I think of it

Hi yes ASHP

 

[Aaron b]

I've just been doing a SPD risk declaration and getting the customer to sign. I'm doing these for new circuits and alterations. It's only a couple of tick boxes no calculations. It also prompts thought about what type is required.

 

[loz2754]

TBH I'd be more concerned about the correct type (Type A) of upstream RCD being in place than I would about SPDs.
Especially if the ASHP uses an inverter drive.

 

[Aaron b]

I'm not giving an option with RCD type. If it's the wrong type I'm upgrading them. If it's an easy upgrade a SPD makes sense.

 

[swaRRR]

Why you using 2.5 with a 16a? Could use 1.5.

 

[SparkyChick]

Why you using 2.5 with a 16a? Could use 1.5.

2.5mm gives more flexibility with regards to cable routing and distance than 1.5mm due to it's reduced voltage drop (greater distance for a given design load) and overall larger current carrying capacity (2.5mm can carry the design load of 16A for all but one listed installation method).

Appendix 17 of the BBB also makes reduction of energy losses in the electrical installation a consideration for the design of installations. Given an ASHP is going to be running for a long time, the choice of 2.5mm will help reduce running costs by reducing losses in the cable. 1.5mm drops 29mV/m/A, 2.5mm drops just over half that at 18mV/m/A, so for a given cable length it will reduce needless loses by just under 40%. Over the life of the installation, that could add up.

 

[Dave OCD]

Yeah, but take into account cable length, insulation,volt drop etc and 1.5 would soon become a very poor choice.

 

[Dave OCD]

SC beat me to it, and with a much more comprehensive post too.

 

[davesparks]

Why you using 2.5 with a 16a? Could use 1.5.

Considering its a housing association job it has probably been specified by someone else and the OP is working to a spec. So if they were to use 1.5 instead of 2.5 they'd not get paid for failing to meet spec.

 

[Ian1972]

The housing association haven't specified any cable size, SPD or anything I'm just installing to the heat pump manufacturers requirements, regarding installing a SPD I'm not 100% sure if it's required or if even an risk assessment is required for a residential dwelling