by BLAKEY1963 »
Tue Jul 24, 2007 12:43 am
[quote="chrissy"]I have had a new shower (8.5) intalled and in the booklet it states that a 38amp fuseis needed. I have a 6mm cable already and the distance from fuse box to shower is 35 feet. I have done a voltage drop check and it is showing 0.6% and it says you can go no higher than 5%, Some people are telling me this cable is ok and some are saying I need a 10mm cable. The cable is in condut, Can you please advise me. Also the isolater switch is getting warm, should this be happening as an electrician says it should be but I am not happy with his answer.[/quote]
CHRISSY
38 AMP IS NOT A STANDARD RATING FOR A PROTECTIVE DEVICE. THE NEAREST WOULD B 40AMP.
RATING OF YOUR SHOWER USING SUPPLY STANDARD VOLTAGE WOULD B 8500 WATTS DIVIDE 230V = 36.96 ( ROUNDED UP 37 AMPS )
RATING OF 6 MM2 ENCLOSED IN CONDUIT FROM TABLE 4D2A PAGE 222
BS7671 IS 38 AMPS. BUT THERE COULD BE FURTHER DERATING OF CABLE BY IT PASSING THROUGH THERMAL INSULATION OR ENCLOSED PARTIALLY IN A WALL, FLOOR SPACE , OR CEILING VOID.
THE RATING OF LOAD IS CLOSE TO CURRENT CARRYING CAPACITY
AND WARMING OF CABLE COULD BE IT BEING CLOSE TO CURRENT CARRYING CAPEBILITY.
I PERSONALLY WOULD USE A 10 MM2 AND CHECK RATING OF SWITCH.
I WOULD USE SWITCH RATED AT 45 - 50 AMP.
10 MM2 GIVES U A RATING OF 43 AMP, INSTALLATION METHOD 4 ENCLOSED IN A WALL ECT.
BLAKEY1963
