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Topic Title: Emergency stop/start switch tripping
Topic Summary: I'm not sure I trust the advice give
Created On: 09 April 2015 06:57 PM
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 11 April 2015 09:23 AM
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I'll do that iomtt, well, I'll do the diagnostics but I'm not inclined to start adjusting things because of the state of the rest of the installation (assuming it hasn't been upgraded).

Anyway, can't believe I'm up so early but I've been to the wholesaler to get bits for the new shed (which is fab) so I had a look at their emergency stop switches.

Some of them are simple make and break and they seem to be the ones with the mushroom shaped stop button (which I was imagining), others have all kinds of options. Expensive kit.

This one might well have special gubbins in it and I suppose the pool company might have overlooked re-setting it. I will let you know all about it and get us some test results. I'm going there with another sparky, just for the chance to see him really, but there will be two opinions on site and he's plenty of experience.

Yes, single phase. Mineral Insulated and a long run from the house. I hope they've not exceeded the capacity of the cable.

Grateful to you for your help.

 11 April 2015 09:39 AM
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So you advised the old Doc to get pool specialists to have a squint. They decided that a new pump was required and then fitted it to an existing starter and probably didn't bother their backsides looking at starting arrangements.


Lyle Dunn
 11 April 2015 11:41 AM
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Hi Zs,

Looking at the photo, it is not an emergency stop unit. It is a simple DOL motor starter. These can be used for stopping a motor in an emergency, but are not compliant with the legislation that would apply to a proper emergency stop. If you remove the cover (as others have said), you will more than likely find a motor thermal overload unit, still set for the old pump. Have a look at the info for the MEM ADS8 starter that Mike linked to. This a universal 1ph / 3ph starter that is also rated to IP54. In the data sheet, there are some wiring drawings at the end. You can also see the overload relay in the photos - the contactor is at the top, the overload is at the bottom with the white lever on it.


 12 April 2015 10:09 AM
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I reckon you're right Alan et al and I reckon Lyle thinks what I think...

I've just sent one of my firm but polite emails to Dr H suggesting that the pool company have accidentally overlooked a required adjustment and that he get in touch with them before I go over and carry out a thorough inspection of the electrical installation of the new piece of kit and check his technical spec and certification. I expect they'll turn out before Friday and open it.

It's a shame, here's an elderly gent who in his time was described as eminent in his field (geriatrics I gather). Now he is a wealthy, infirm and somewhat quirky character and I expect it is easy to pull the wool over his eyes and get money. I suppose it's why I keep some of these customers and don't refuse to turn out for them (pre-tiring is going well here, have laid down the cable chaser and heavy tools). I may well be asking you if you want to re-wire that pool house.

 12 April 2015 10:43 AM
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It definitely looks like a DOL unit, probably contains a three pole contactor with an overload on the bottom. Sounds very much like the overload is undersized for the new pump but one other thing to look out for is it being a three pole overload and only supplying a single phase load, therefore only using two of the overload poles, this will cause the unit to trip because they are designed for three phase and this would indicate "single phasing" on a three phase motor. If using a single phase motor in a three pole overload, you need to return one of the outgoing lines back through the overload to get equal current in all three poles.


"be careful of what you write"

Edited: 12 April 2015 at 10:54 AM by Paradigm
 12 April 2015 09:33 PM
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Am I right in thinking that the pool equipment does not need a emergency STOP as there are not any exposed heating elements and/ or rotating parts?

Second point, am I right in thinking a emergency stop does not necessarily switch off the electrical supply as it may be needed for a electric brake?

Next point, presumably along with the start/ stop controller, which can be used as an emergency switch, a lockable isolator is required if any of the pool equipment that is controlled electrically from the controller is remote from it, to allow safe working when carrying out maintenance and repairs?

 17 April 2015 10:04 PM
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Well, waddayouknow,

I had a last minute cancellation. I didn't mind because I'm supposed to be on hols.

As if by magic, the pool pump man called Dr H and said he'd forgotten a widget or something and could he go back immediately, before the electrical inspector lady attended.

Thank you, your advice was at the core of the email I sent and clearly made a difference.

IET » Wiring and the regulations » Emergency stop/start switch tripping

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