Testing for minor work....

[Mikey_A]

Hello all, i'm installing a couple of PIR 500W floods for a friend. They're going to be independant of eachother and fed from the upstairs ring and conected to SW FCUs, protected by 3a (or maybe 5a) fuses respectively.

I'm a developing domestic installer and have recently gained my C&G 2381 and close to completing the EAL domestic installer qualifications.

Any minor work that i do i'd like to do to the book (and rightly so) and would like some help on the testing aspect so that i can give him a MWC to complete the job.

I've already been to the house and tested the existing ring to make sure it has no faults. All is ok.

When i complete the work tomorrow i want to be able to perform the neccessary tests to complete a MWC. So i need to clarify a couple of things:

1. IR test for the new circuit to be tested at the FCU (before connection)?

2. The protective device protecting the circuit (part 2) will be the 3a fuse in the FCU and not the 30A fuse protecting the ring circuit?

3. I take the EFLI readings at the connections in the flood light?

Sorry if my questions seem a little stupid but i'm still on a huge learning curve and want to be 100% certain of what i'm doing before i do the job.

 

[securespark]

You need to megger the circuit you are attaching the new wiring to, to prove it is sound. If you megger the end of the 2.5 feeding the spur (with the other end attached to the existing circuit) you are testing both existing & new wiring.

Nope. The protective device will be the fuse or breaker at the origin.

You take your EFL from the furthest point on the new wiring, so yes, from the light fitting.

 

[Mikey_A]

Cheers secure....

 

[Taylortwocities]

Its always fun doing EFL tests up a ladder, under the eaves, wondering if the pigeons are from the Part P police

 

[lazygit]

Nope. The protective device will be the fuse or breaker at the origin.
quote]

So if have run a light circuit in 1mm cable from a 5A fused spur, You put 32A breaker as the protective device and 1mm as the cable size?
Where do you mention the 5A fuse? Surely this is protecting the 1mm cable, not the breaker protecting the ring.

Please clarify as there seems to be nowhere else to add this information

Regards

 

[industryspark]

lazygit wrote

So if have run a light circuit in 1mm cable from a 5A fused spur, You put 32A breaker as the protective device and 1mm as the cable size?
Where do you mention the 5A fuse? Surely this is protecting the 1mm cable, not the breaker protecting the ring.

Please clarify as there seems to be nowhere else to add this information

Regards

suppose you could argue a case for both but i think securespark is correct personally. the circuit you have altered is the ring so you put 32A down as the protective device. just mention the FCU and the smaller rated fuse in the 'details of minor works section'

easy in'it!

 

[Mikey_A]

Guys

Can i connect a SW FCU off an existing spur to supply a fixed external floodlight?

The existing spur is a double socket outlet off the upstairs ring.

 

[securespark]

You can only supply one 13A accessory from an unfused spur off a ring or radial circuit.

If you have an unfused spur already, you need to fuse it down to 13A before you can add further outlets.

 

[ricicle]

Guys

Can i connect a SW FCU off an existing spur to supply a fixed external floodlight?

The existing spur is a double socket outlet off the upstairs ring.

No, you are creating a spur off a spur.

 

[Mikey_A]

Forgive my ignorance, but....

So that i have a full understanding can someone explain to me why you can't spur off a spur?

 

[Spark123]

You are only allowed one accessory per unfused spur, see the onsite guide Appx 8 p153.

 

[Mikey_A]

You are only allowed one accessory per unfused spur, see the onsite guide Appx 8 p153.

Yep, got that part. We're told you can't do it. But i need to understand the reasons why?

 

[davy_owen_88]

To put it simply, it's so you don't overload the cable between the ring circuit and the spurred accessories, and also so that you don't unbalance the ring circuit to the point where a single leg is carrying more current than it is rated for.

 

[Mikey_A]

Thanks guys, every day is a school day!

 

[ColJack]

cable rating...

2.5 = 27A

max load of single spur point...

FCU = 13A
single socet = 13A
double socket = 2 x 13A = 26A..


theoretically, you could put 2 FCU's on one spur and argue that you can put a double socket in.. but loading on a double socket is unlikely to reach it's maximum..