water and electrics

Postby 333rocky333 » Wed Dec 05, 2007 11:53 pm

Not really diy but anyone know about steamrooms,
At work i was called to replace a shorted out panic switch within a commercial steam room, it was a IP65 rated plastic e-stop unit, when tested it was found to be 240 volt, it is unknown at present if it is rcd protected.
It appears it may be a legal req to have a panic switch within the unit

I refused to do the job and advised not to use it until they got in a contractor with more specialist knowledge.

My grounds were
1, I did not feel ip65 was enough for steam.
2 The switch internal connections were open and unsuitable, as the condensation was building up within the switch and shorting them out,and would i assume happen no matter how well the outside was sealed.
Advised a pre wired type switch with all connections presealed by manufacturer.
3 Did not feel voltage was suitable for the circumstances.
Advised low volt system or air type switch used
Checked regs but not able to find much.

Not gonna do job,as not prepared of the risk, but appreciate other views or pointers where to look,as they think i am overreacting.
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Simply Build It

Postby BLAKEY1963 » Fri Dec 07, 2007 1:07 am

A steam room would be an area of increased shock risk
due to the enviroment.
A switch that is pre wired and even as far as being ip8x
rated , ( submersible in water ) and able to cope with high
ambient temperatures , as you pointed out would seem
the remedy.
i would also say that SELV voltage should be used.

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Postby 333rocky333 » Fri Dec 07, 2007 8:04 pm

Thanks for confirming that.
Regarding selv, i have heard some 240/12 volt trans do not comply , as under fault condition could let through a higher voltage.(switchmode)
[b]I AM NOT DOING THE JOB[/b] but would like to know are wire wound or switchmode trans safest.
Are most of the small electronic trans switchmode.
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Postby sparx » Sat Dec 08, 2007 12:22 pm

Hi, switch-mode psu's are for providing regulated supply for equipment and usually give a DC output which you don't want/need.
A straight forward double wound 230/12v transformer will give a supply which you would use to switch a contactor coil via your ESPB, the contactor in a safe location [next to control unit?] would then switch your main load. Could mount both Trans. & contactor [& mcb @ 6A for control circuit] in plastic enclosure, have done similar myself, regards SPARX
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Postby 333rocky333 » Sat Dec 08, 2007 7:07 pm

Sorry, What do you mean by an espb,do you mean extra safe push button.
I thought that method was a possibility, but as the existing switch is supplied from elsewhere 240v ,there is no neutral at switch, the tran also really needs to be fed from the same supply where ever that is ,rather than having two lives in same enclosure.
Double insulated wire wound trans appear to be tested about 3000v and there are reinforced insulation medical grade tested to 4000v.
our concern then would be the relay or contactor switching the 240v load would then need to be rated as high as that.
What we cannot find is any info of what the actual legal requirements are ,even the specialist steam shops wont advise.
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Postby ericmark » Mon Dec 10, 2007 2:34 am

As to safety at 230 volt I would also be surprised if it would be allowed only if there is no option like with shower unit would it be allowed.
But as a SAFETY switch then it may need to be duel wired. If it is protecting against something which would not be repairable i.e. death then everything needs to be duel. Most use two normally open contacts but some use one normally open and one normally closed and feed a special safety relay which monitors the time between both contacts operating and activates if there is too much time between the two contacts operating. Always Red or Yellow no other colours allowed. (Seems US spell check). The relays normally have the transformers built in so whole question on switch mode is redundant.

As to switch mode there are two types primary and secondary the latter not very often used where voltage can be regulated before or after it is transformed which both can be to BS 3535 or not and if they are OK have a shield with two circles overlapping and a line through where they overlap shown just after irons in Code of Practice for in-service etc. But the main problem is they have a range output which does not include 0 for example 1 amp to 20 amp so supplying something that switches off would be a problem. If they did not comply then using a mouse on a computer would cause problems as mine is not earthed nor does it have to double square showing double insulation. I have questioned the fact that the power supply on a desk top has all the details hidden by PC case but the way PC's are built putting details on main case would not work as too easy to swap power supply but look on a Laptop power supply and they are all there. We just have to accept desk top as OK. In same way as every 110volt three core cable I have seen have wrong core colours should be Brown Black and Green/Yellow for split phase but always seem to be Brown Blue and Green/Yellow which denotes a 110v - 0 supply not a 55-0-55 volt supply it is the example I use when employers insist they follow 16th Edition to the letter.

So in this case not electrical regulations but the general health and safety regs.

All best Eric

Postby sparx » Mon Dec 10, 2007 5:41 pm

Hi rocky
I presumed the steam room was electrically heated so there would have to be a mains control panel nearby that the Emergency-Stop-Push-Button connects to?
As I said if so then power must be there, you would just be using the existing button to switch 12Volts to operate coil of contactor so no mains anywhere in steam room!
Your contactor could be any type as it provides electrical isolation between controls @ 12V & heater @ 230V or am I missing something,
(12v on espb/coil) & (230v on contacts/heating circuit)
regards SPARX
NB could use air operated switch, cheap, NO WIRING in room tube to switch in box outside room, as used in some spa baths.
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Postby 333rocky333 » Mon Dec 10, 2007 10:11 pm

sparx, get what your saying , the whole set up is iffy, and im keeping away ,its for an alarm, we did not go into it but there is probarly a box for the heater, but the alarm is one of five in the building,and the existing supply240v could come from anywhere ,possibly 30 metres away by the sirens and flashers ,if they put the tran there the selv wires would be in conduit with the mains so would not recomend that either.

It is a large commercial gym,and possibly the alarm may even be on different phase, to the heater box.

I am with you on the idea , but would worry coz there would then likely be 2 mains supplies in your box and also about the switched 240 flashing over to the control 12v within the contactor in a fault, unless the contactor was tested to at least 3000v and certified same as the selv tran.
Dont think it would still be a selv system if there was a risk of the 240 populating the 12v within the contactor

I think there best option is a complete 12 volt system installed like you say ,with a suitable switch, feeding a new 12v siren/flasher and strip the 240 v out completely.

Thought about air switch but may have problems latching the alarm as it proberly has to reset within the room ,to make sure the staff check.

It will be interesting to see what they do as the last bloke is lucky he did not kill someone.
Hope he has not done all there sites.

There moaning like hell coz they cant use it,since I told them about the 240 volt, the manager shut it down ,they all moan but none of them will switch it back on coz there scared of the consequences.
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