Connection of 2 convector heaters using armoured cable on a radial circuit

[Sparky 63]

Evening Gents,
Im looking for some advice, I have to connect two convector heaters on a radial circuit - I will be connecting each outlet via fused spur flex outlet, I was going to use a 3x3 adaptable box to terminate the one armoured then connect in singles to fused spur outlet and then back through adaptable box to armoured serving other heater- would this be ok?

Thanks

Sparky 63

 

[Darkwood]

Without any ratings, cables sizes, OCPD rating etc i can't comment about whether the circuit is correct but your principle idea is ok.

The spurs are electrically connected in Parallel they are positionally in series with each other please don't mix this up.

 

[Sparky 63]

Many Thanks Darkwood, im using 2.5mm 2 core and earth supplying 2 x2kw heaters protected by 20 amp RCBO TYPE B, I dont think it is possiblke to terminate to such armoured into a a single back box.

 

[MDJ]

Many Thanks Darkwood, im using 2.5mm 2 core and earth supplying 2 x2kw heaters protected by 20 amp RCBO TYPE B, I dont think it is possiblke to terminate to such armoured into a a single back box.

If you gland the armoureds into couplers you will get both cables into a metal clad spur unit easily.How far is the cable run in meters?

 

[Darkwood]

If your using adaptable boxes to make it easier you only have to run 1 set of cables to each spur, you don't have to loop in and out of the 1st one... as long as your cable calcs comply and Zs is good then you can spur of your joint out with one L/N/E to each heater.

 

[Sparky 63]

Hi MDJ ,one radial is max 45m the other one approx 60m.

Cheers

 

[MDJ]

Hi MDJ ,one radial is max 45m the other one approx 60m.

Cheers

So to clarify, you intend to run an armoured cable 45 mtrs into a adaptable box, then loop another armoured from that box a further 15 mtrs? then connect one spur to the adaptable box and the second armoured straight into the second spur? and 60 mts of cable in total for a 4 kw load wired in 2.5mm2 cable and connected to a b rated 20 amp MCB?

 

[Darkwood]

Hi MDJ ,one radial is max 45m the other one approx 60m.

Cheers

That changes everything .... you have 100m run you need to show your cable calcs you are giving us bits of info in dribs and drabs we have told you in principle your idea is ok but it seems you don't want to work out your cable sizing using the correct method.... are you an Electrician or DIYer ?...

Work out your cable size check your volts drop is ok and show your workings ... we are happy to correct minor errors but i personally am not here as a free design service.

As MJD has asked is this 100m run in total or 60m run in total?

 

[Bobster]

Without spending more than 10sec looking at this thread, volt drop is screaming at me.

 

[R G]

Do your volt drop calcs especially important if your using just one circuit also taking into account any derating factors to come up with the correct size circuit ..

 

[MDJ]

I think we need clarification from the op first as we are all confused at what is the length of run, is it 60 mtrs or 105 mtrs?

 

[Sparky 63]

Hi
one circuit is one FSU at at approx 35metres and the second spur on that radial say at 45 meters- the second circuit is separate radial running 50 metres to the first FSU and then another10 meters to the last FSU on that radial backed with 20A RCBO.

Thanks

 

[MDJ]

Nope sorry still just can't understand your point.

 

[Sparky 63]

Hi sorry as not clear
circuit 1 - radial - first fSU at 35m second at approx 45m
circuit 2 - radial - first FSU at 50 m and second FSU at 60M

Thanks

 

[MDJ]

so 2 different radial circuits feeding 2 different heaters on each and 2 20 amp breakers? one circuit at 45 mtrs and the second circuit at 60 mtrs?