Wiring a start/stop machine switch

[MarkW]

Evening all!

I could do with a bit of help from any electrically-minded folks out there. I have a start/stop switch to fit to a basic 240v single phase extractor fan in our lab, but I can't figure out how to wire it up. I took a look on the manufacturers website (no joy) and did a Google search, but I'm still none the wiser!

There appear to be four banks of twin contacts inside, making eight possible connection points. Hmm...

Any help very much appreciated!

Mark

[TimR]

Hire a professional as you may void the insurance for the premises

[MarkW]

It's an extractor on a bespoke piece of kit we built, fitted on the mains cable between the plug and the unit, so the insurance won't be an issue. We just need a way of turning the thing on and off without getting up and walking to the socket.

[Westbeef]

I assume your power will be coming from a motor? I can ask an electrician at work for you if this is the case - or will it be from the mains?

[rennie]

There will be 2 sets of normally open contacts and 2 sets of normally closed contacts

they will have no or nc marked on them

[MarkW]

There will be 2 sets of normally open contacts and 2 sets of normally closed contacts

they will have no or nc marked on them

Correct: the two black blocks are NO and the two red ones are NC...

[MarkW]

There will be 2 sets of normally open contacts and 2 sets of normally closed contacts

they will have no or nc marked on them

Correct: the two black blocks are NO and the two red ones are NC...

What do I do now?

[Hoggs]

There will be 2 sets of normally open contacts and 2 sets of normally closed contacts

they will have no or nc marked on them

Correct: the two black blocks are NO and the two red ones are NC...

What do I do now?

 

Page JRH to the thread!

 

BING BONG

[rennie]

sorry I'm about to leave for work,

if someone hasn't beat me to it I'll try to answer from there later

[JRH]

Unfortunately you can not use that unit on its own. It is designed as remote start stop for a motor controlled by a contractor. What you need is an isolator.

Like this

https://uk.rs-online.com/mobile/p/non-fused-switch-disconnectors/3939721

I'm just going out will try to update in the morning but feel free to pm me.

[MarkW]

Ah! That would explain why I couldn't find any info on how to connect it! No worries - I'll exchange it for the one you suggest.

Thanks guys and gals!

[JRH]

Ah! That would explain why I couldn't find any info on how to connect it! No worries - I'll exchange it for the one you suggest.

Thanks guys and gals!

 

If you have a Toolsation near you there is this, it's cheaper

http://www.toolstation.com/shop/Electrical/d190/Industrial+Accessories/sd3080/Rotary+Isolator+4+Pole/p88825

Ignor the 4 pole, just use 2 and switch the live and neutral. I am assuming that as the fan is running form a standard 13 amp socket this is more than adequate.

HTH

[Joeman]

Why not use an actual fan isolator switch?

http://www.toolstation.com/shop/Electrical/d190/Crabtree+White+Wiring+Accessories/sd3354/Crabtree+Fan+Isolator+/p11750

http://cdn.toolstation.com/images/141020-UK/800/11750.jpg

[MarkW]

It's for surface mounting in a stainless steel glovebox to operate the extractor attached to a plate sprayer, so ideally it needs a degree of resistance to water ingress (the original we bought was rated for partial immersion IIRC).

[JRH]

If you need water resistance may be better to look at this as I'm not sure the rotary isolator is water resistant.

http://www.toolstation.com/shop/p50651

This is IP65. Obviously the cable glands need to be resistant also.

It will probably have a single pole switch contact so just break the live.

[MarkW]

Top man JRH - and it's cheaper than the one we're returning.

[JRH]

Out of interest, what are you spraying and what with?

[MarkW]

Out of interest, what are you spraying and what with?

Mainly dimethoate, carbendazim and sodium trichloroacetate through a custom-made spray tower onto glass plates on an analytical balance. They are horrifically toxic, so we need to vent them from the spray cabinet as quickly as possible, but as the spray deposition is weighed in real time we can't have the extractor running during application otherwise the balance goes haywire.

[JRH]

Out of interest, what are you spraying and what with?

Mainly dimethoate, carbendazim and sodium trichloroacetate through a custom-made spray tower onto glass plates on an analytical balance. They are horrifically toxic, so we need to vent them from the spray cabinet as quickly as possible, but as the spray deposition is weighed in real time we can't have the extractor running during application otherwise the balance goes haywire.

 

I take it that none of those chemicals are flammable and likely to cause an explosion then in the presence of an electrical spark.

[MarkW]

Out of interest, what are you spraying and what with?

Mainly dimethoate, carbendazim and sodium trichloroacetate through a custom-made spray tower onto glass plates on an analytical balance. They are horrifically toxic, so we need to vent them from the spray cabinet as quickly as possible, but as the spray deposition is weighed in real time we can't have the extractor running during application otherwise the balance goes haywire.

 

I take it that none of those chemicals are flammable and likely to cause an explosion then in the presence of an electrical spark.

No, they should all be fine.

Incidentally, there was a story in the industry some years ago of a lab who were conducting pesticide residue analysis on glace cherries, the extraction procedure for which involved macerating the glycerine-soaked cherries in nitric acid. Apparently it dawned on them that they had inadvertently manufactured nitroglycerin when the fume hood exploded.