Armoured cable 16mm or 25mm

[Cliff C]

I am not an electrician. Can anyone help please?

I have an outbuilding which I am converting into two offices.

The building is currently served by a 16mm armoured cable running underground from my house, the distance is about 100 metres.

Potentially the building could have a maximum of the following appliances:-

2x2kw electric oil filled radiators
1x1.5kw electric oil filled radiator
Hand wash 2.5kw
Electric Kettle 2.5kw
Saniflo 400 watts
Vacuum Cleaner 1kw
4 Fluorescent Lights
2 Computers
Total aprox 13kw

Will the existing 16mm cable be adequate or will I have to have it replaced with a 25mm armoured cable.

Thank you

 

[Wilko]

Hi - 100m is a long run and as usual the heating becomes a load problem as it might be on all day.

 

[telectrix]

the breaker is there to protect the cable from overload/short circuit, not to minimise volt drop. it' s Ib that should not exceed 25A, not In.

 

[telectrix]

Hi - 100m is a long run and as usual the heating becomes a load problem as it might be on all day.

yeah. but OP would have a warm lawn.

 

[Spoon]

Get yourself a wood burner and save yourself 3.5kW..

 

[telectrix]

wood shed, burn nice.

 

[DPG]

wood shed, burn nice.

Typical scouser attitude

 

[Andy78]

wood shed, burn nice.

No no, you get extra wood to put in the burner. You don't have to snap bits off the shed.

 

[DPG]

No no, you get extra wood to put in the burner. You don't have to snap bits off the shed.

He misunderstood bless him. It's an age thing.

 

[buzzlightyear]

i'm at a loss to see why he should fit a 25A breaker protecting a 16mm cable.

you at a lose ,me thinks some one lost the plot .

 

[Cliff C]

bear in mind that not all loads will be in use simultaneously. applying diversity, I'd allow for an aveage load of 8kW. that equates to c. 40A, so as far as current capacity, 16mm will,be fine. volt drop however may be a factor.

Thank you everyone for your advice.

The reason I put my post was that I had two conflicting quotes from local electricians.

One said that my existing 16mm armoured cable would be OK and quoted me £480 to upgrade my outdated fuse box with a new consumer unit including safety certificate.

The other said that 16mm would be unsafe and a fire risk and quoted me £6900 to replace with 25mm armoured cable.

Will my 16mm cable by unsafe and a fire risk, or just a voltage drop that will mean I might have to replace my existing fluorescent fittings?

 

[Spoon]

Thank you everyone for your advice.

The reason I put my post was that I had two conflicting quotes from local electricians.

One said that my existing 16mm armoured cable would be OK and quoted me £480 to upgrade my outdated fuse box with a new consumer unit including safety certificate.

The other said that 16mm would be unsafe and a fire risk and quoted me £6900 to replace with 25mm armoured cable.

Will my 16mm cable by unsafe and a fire risk, or just a voltage drop that will mean I might have to replace my existing fluorescent fittings?

What size circuit breaker/fuse did the electricians quote, for this circuit?

 

[Wilko]

Hi - 16mm SWA buried is good for 78A single phase, which is about 18kW load. Your loads add up to less than this so in my humble opinion it's not the 16mm that might be a fire hazard. (It might be something else he's spotted?). Certainly there would be a significant voltage drop over 100m.

 

[Cliff C]

What size circuit breaker/fuse did the electricians quote, for this circuit?

The quote wasn't detailed and did not say.

 

[Spoon]

The quote wasn't detailed and did not say.

Ok.
As mentioned above, if you want to use the existing 16mm cable then the max size breaker/fuse you can have is 25A. Anything bigger and you will exceed the 3% voltage drop for your lighting.

 

[Nebu1a]

Could you have a small LPG combi-boiler fitted for your heating and hot water. Sockets on a 20amp radial and lights on a 6amp.