Category III overvoltage - Hot Tub

[Chris White]

I read the statement below in the manufacturers guidance for installation of one of their domestic 32A hot tubs and am embarrassingly confused. Could anyone please let me know what a category III overvoltage is, and what type of device is required for complete disconnection in its event. I'm assuming they don't mean an SPD as this will only give momentarily disconnection to earth whilst the transient is detected.
Statement:
For connection to the power supply network, we recommend installing an isolating muti-pole switch, which will ensure complete disconnection in the event of a category III overvoltage; these devices must be positioned in an area that complies with safety regulations.
nection to the power supply network, we recommend installing an isolating muti-pole switch, which will ensure complete disconnection in the event of a category III overvoltage; these devices must be positioned in an area that complies with safety regulations.

 

[nunthe wiser]

Cat 3 is distribution equipment. I’m not sure of overvoltage device requirements I.e certain percentage of design voltage.

 

[Pete999]

Cat 3 is distribution equipment. I’m not sure of overvoltage device requirements I.e certain percentage of design voltage.

See BS 7671 for voltage parameters.

 

[buzzlightyear]

we recommend installing an isolating muti-pole switch, which will ensure complete disconnection in the event of a category III overvoltage; these devices must be positioned in an area that complies with safety regulations.

and rcd protected .

 

[davesparks]

This sounds like a bad translation from another language more than a sensible technical requirement.

 

[buzzlightyear]

This sounds like a bad translation from another language

yeah, double Dutch.

 

[Lucien Nunes]

I'd read it as 'Means of isolation must be installed that meet the requirements of IEC 60664-1 overvoltage category III'. This is the normal category for isolation within a fixed installation. A switch-disconnector will usually meet the specs whereas a lightswitch won't.

The overvoltage categories specify the expected maximum transient voltages that are likely to arise in real installations in the event of a serious transient event such as a lightning strike on an overhead supply. The nearer the origin and the higher the system voltage, the higher the voltage peak the equipment should be able to withstand. The overvoltage category relates the actual maximum withstand voltage to the rated system voltage. DNO equipment must meet overvoltage category IV, installed switchgear category III, portable appliances category II. The actual voltages for all the categories, for each possible supply voltage, are given in table F4 of the IEC standard.

 

[Welchyboy1]

I read same sort of language from a canadian hot tub firm

As above, double pole isolation and rcd protected

 

[PEG]

I was only reading the translation on a control box,yesterday...most likely Chinese origin Spa tub. It read "multiple applied lighting..." and installer thought this was regarding led's...further investigation revealed it was describing lightning,not lighting...

....Send three and fourpence...we're going to a dance....

 

[Chris White]

Many thanks for your replies. Makes sense now when you put it in plain English - i.e. isolation that meets the requirements of IEC 60664-1 overvoltage category III.

 

[PEG]

I don't reckon any of the tubs,i've seen,are good for 100 million volts of lightning....
I can,however,think of individuals to place in these hot-tubs,whilst testing....

 

[static zap]

Read some clever ones that "Should" trip RDC as a logged event .. To prove correctly configured !
(another non-UK design) ..begin to doubt things as RTFM..