Hot tub problem

[nickblake]

Ive taken over a job from another spark who never turned up ,embarrasing because i know and have alot of respect for the guy .first thing i noticed was the supply cable 6mm 2 core swa from the house to a meter box, (looking at the load i felt this should have been at least a 10mm) then from there to a caravan which is on a 16 amp socket and the Pen conductor is to an earth rod , then in a 6mm 3 core SWA to the hot tub ,the Ib is 27.9 amps and the cable length from the house to the hot tub is 30 m with a 63 rotary switch to isolate calculating the voltage drop is 6.11 v so thats fine ,Zs is 0.91 a little hig but still within when all is running the supply voltage drops around 8 volts the installation is protected by 2 RCD's one RCBO 40 amp in the house and a main switch RCD in the meter box hot tub then protected by a 32 amp mcb,i knoe the RCD 's should be time delayed but are not and the current rating is a little to high for theincomming cable but that will be delt with the main problem is for no apparent reason the hot tub cuts out at random times ,the hot tub guy says its the supply as it drops when the heaters and pumps are on ,but i dont thing so , i feel its the hot tub ,what do you guys think any idea's

 

[Sintra]

Had a similar sort of encounter with a commercial soft whipped ice cream machine which kept on cutting out especially in the early evening. Again volt drop on supply circuit was just within the limits and again the manufactures were consulted and the machine was tested and found to be fine. What was happening was the supply voltage was dropping to about 220V which is within limits but with the extra VD of 6V this was down to 214V at the appliance and the lower limit of voltage for the machine to operate was 216V. Cable upgraded from 2.5mm to 6mm and problem solved. Don't know if you might have a similar problem.

 

[UNG]

What is the make of the control equipment on the tub

Had a few problems in the past with Spa Quip kit in the past and alot of the problems where down to poor soldering on the control PCB

 

[nickblake]

Thanks it does sound a very much so everythings been pushed to its limits ,think the guy didnt want the job ,bit fiddly ,but a few second calculating the loadings and voltage drop would have solved the problem ,probably upgrade just the supply cable to the CDU for the hot tub and caravan and then retest, caravans on a 16 amp plug and socket so if i use a 10 mm it hopefully should be better im tempted to use a 16mm 3core ,but ive a 10mm SWA 3 core left from a job and its just long enough thanks for your comment sintra

 

[nickblake]

What is the make of the control equipment on the tub

Had a few problems in the past with Spa Quip kit in the past and alot of the problems where down to poor soldering on the control PCB

ill be honest with you ive not looked its a new hot tub so every thing stops at the supply