CABLE SIZE? CAN YOU HELP?

[DCN]

I am trying to connect the following to a fused board which will then lead back to a new connection off an unused fuse off my consumer unit:

2 x Air con unit (1400W, 6.7A)
1 x Electric heater (1500W, 15A)
1 x Security light (15W, 5A)
2 x Fluorescent lights (??W, 5A)
1 x Double socket

I would like to wire up the fused board and the above and get an electrician to check it and do the final connection to the consumer unit. I am having trouble calculating what the start up load would be for the above and hence the cable size back to the consumer unit. The cable run is about 5 metres. Can anyone help?

 

[ban-all-sheds]

Can anyone help?

Yes - your electrician can.

I am having trouble calculating what the start up load would be for the above and hence the cable size back to the consumer unit.

Anybody would have trouble calculating the startup load, without being told the startup surge rating of the aircon (nothing else has a significant surge). But if you're putting yourself in the position of design authority for this, then you should investigate how much effect startup surges have on cable size and how much on the characteristics of protective devices, and how that can feed back into cable size.... Also bear in mind that aircon units have compressors, and they generate a surge every time they kick in.

(1400W, 6.7A)
(1500W, 15A)

An inconsistency here, I think?

I would like to wire up the fused board and the above and get an electrician to check it and do the final connection to the consumer unit.

This work is notifiable - are you getting an electrician to check it for your peace of mind, or are you planning to comply with Part P? Have you spoken to your LABC to see what they require regarding notifiable work not carried out by a Competent Person? Have you got an electrician lined up, and agreed what he will do for you, or are you just assuming that you will be able to find one, and that he will automatically be prepared to do what you want?

 

[Damocles]

1500W=6A approx

Security floodlight might be 150W, 300W 500W to name the standard strip halogen bulb sizes. Only a fluorescent bulb would be as low as 15W. If it is a flood, assume 500W=2A.

Double socket would be rated at 13A but this might depend on what you expect it will be used for. In general you should allow it the full power it might draw, but if you are pushed then you might base demand on a reasonable assumption of steady current rather than peak possible.

What is all this lot for? This might give us some idea of power demand. So far sounds as though you might put this lot on a single 32A breaker, or a 30A fuse, if you have plug in fuses.

Do you plan to use the air con and the heater at the same time?