Cable Gland

[Former MemberParticipant @formermember19781]

[This posting has been removed]

[Former MemberParticipant @formermember19781]

[This posting has been removed]

[Robert Atkinson 2Participant @robertatkinson2]

Posted by Clive B 1 on 22/02/2020 19:36:19:

1/ Ok fellas, do you think it would be a good idea to earth the planer?

2/ Do I need to run an earth with the emergency stop buttons and could I use the spare wire in the twin cable already used?

3/ Can I get away with 1.5mm 5 core cable to connect from the box on top of the motor to the DOL starter, ie live, neutral, earth power supply for the motor and the line out and line return from the emergency stop buttons, 5 cables in all?

I believe 1.5amp cable is good for up to 20amps if clipped direct and I don’t think there will be a huge voltage drop as the cable length is only about 8 feet from the motor to the 3 pin socket outlet and it will be in air as I need to be able to move the DOL around to whatever side of the machine I’m working on.

4/ I’d like to bring the emergency stop cabling through the hole in the wooden table and into the box on top of the motor so all the cabling comes to a central point, I’ve shown them in blue, also going through same hole in the table would be the 5 core cable to the DOL starter.

The issue of getting the cables through the angle iron, I know I could simply loop them under the angle iron as they will be under the table and not really seen.

I just wondered if there was a tidy way to do it.

I guess at the end of the day jobs can usually be done, some look tidy and others look crap but they both work.

5/ Again with the starter which is going to be the neatest, try and run a single 5 core cable from the box on top of the motor to the DOL starter, instead of 3 core and then another two cables line out and return form the emergency stop buttons?

The motor by the way is 1.5HP 6.9Amps.

I’ve included a few pictures as it may help show what I’m trying to do.

Not just a good idea, it's essential that you earth the motor and the metal frame. Earth wires shold only be green/yellow (or the bare conductor in fixed wiring with a green yellow sleeve). Never use brown, blue, red or black for an earth connection.
1.5mm2 should be OK for this application if the saw is supplied by a 13A plug.

Robert G8RPI

[Mike PooleParticipant @mikepoole82104]

As a wartime measure the Pressed Steel factory chose to use RED as the earth. I last came across one in 1974 as an apprentice. It was mandatory to rewire it safely.

Mike

[Johnboy25Participant @johnboy25]

From the photo of the contractor & overload relay/trip – it looks like only two contacts are used. All three should be used to ‘balance’ the loading of the overload mechanism when used on single phase supplies. This can be done looping the ‘live’ conductor back around through the contractor and overload contact. If this isn’t done erratic tripping of the overload will occur.

I can’t see the loop back – it could be there and I can’t see it in the photo… 😳

[Clive B 1Participant @cliveb1]

Bill and Old Mart

My apologies for getting it wrong about weakening the steel, I've reached that age where I can't remember what I did today, never mind what I did yesterday

Clive

[Clive B 1Participant @cliveb1]

Johnboy25

Please don't say that, I'm not really into wiring DOL Starters, tomorrow Sunday I'll take another photo and post it on here so hopefully you will see the connections more clearly.

I'll also do a sketch of the wiring connections and perhaps you would be good enough to put me straight.

It would be a great help if you could use my photo or sketch and draw on it how the wiring should be, as its far better than describing it in words.

I don't want to get someone in to do it, but I do want to get it right.

Thank you for your observations

Clive

[Johnboy25Participant @johnboy25]

Clive…

*contactor – spell checker problem caused by my dyslexia! I’d be be happy to help. John

[Former MemberParticipant @formermember19781]

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[Clive B 1Participant @cliveb1]

Bill

I will certainly earth the planer, I know I’ve got some 6mm or 10mm earth wire kicking around somewhere.

Too daft for words isn’t it I’ve been using this machine ever since I bought it new way back in 1984.

Did I worry about leaning over running machines to turn the motor off, No, did I think about having emergency stop buttons on it, Nah I never even gave it a second thought after all that’s how the machine was made by the experts.

Strange isn’t it when you get older you think what the heck am I doing.

By the way I like your terminology “A Senior Moment” I can see me using that phase more and more in the very near future.

Clive

[Clive B 1Participant @cliveb1]

Johnboy25

I’m just glad of the help you guys are giving me to bother if someone has spelt a word incorrectly, as long as I can decipher what they mean then its good enough for me.

What’s more important to me, is the fact you have spotted a possible wire which could be missing.

Have a look at the photo and my wiring sketch hopefully you will be able to tell if there is anything wrong with the purposed wiring.

Clive

[Clive B 1Participant @cliveb1]

Guys or Ian P

Ian P 21-02-20 reply to my question of emergency stops, he said “Based on what I can determine from your text and pictures I would say that the type of cable and its installation are unsuitable, (if this is some sort of machinery).

If the cable is carrying mains voltage then it should really be three core (with an earth wire)”

Does anyone have any ideas what he means, I suppose I’m just trying to understand how I can earth the emergency stops, as all that’s inside them is provision for a single live cable and the housings themselves are all plastic.

[Clive B 1Participant @cliveb1]

Just a few more photos of the DOL switch:

[EmgeeParticipant @emgee]

Clive

Johnboy is correct in stating best to use all 3 o/l heaters.
Remove the brown live to the motor from T1 (2) and terminate in T2 (4)
Wire a 1.5mm size link from T1 (2) to L2 (3)

Emgee

[Johnboy25Participant @johnboy25]

Clive, Emgee beat me to it!
I concur with Emgee’s configuration. It’s good to see e-stops being fitted. The size of earth or as its known these days – circuit protective conductor (CPC) only requires to be 1.5 mm (squ) green/yellow. This is to provide a sufficiently low low resistance to take the trip/fuse out if a short occurs.

Keep us posted on your progress.

John

[Clive B 1Participant @cliveb1]

Emgee / Johnboy25

Thanks for the low-down on the wire terminations I'll get them swopped over.

I know as a posting gets longer things can get forgotten so can I ask again, I was thinking of bringing the flow and return wires from the emergency stop buttons into the box on top of the motor and running a 5 core cable from the DOL starter also to the box on top of the motor.

The only thing is I don't know whether it would need to be 2.5mm or would 1.5mm cable be ok I'm not sure because there is the motor load to consider??

Anyway have a look at the new sketch hopefully you will understand what I'm trying to do. I was just thinking it might be better than having a 3 core cable and then two twin core cables all cable tied together going into the DOL Starter. Any ideas on that one??

Thanks

Clive

[Johnboy25Participant @johnboy25]

Hi Clive

you mention the motor is rated at 1.5HP Full Load current of 6.9 A. A 1.5 mm flexible cable would be fine.

have a look at **LINK** for cable ratings.

i would prefer motor supply separated from the control/E-Stop circuit.

John

[SillyOldDufferModerator @sillyoldduffer]

Posted by Clive B 1 on 23/02/2020 23:10:23:

…

The only thing is I don't know whether it would need to be 2.5mm or would 1.5mm cable be ok I'm not sure because there is the motor load to consider??

…

I was just thinking it might be better than having a 3 core cable and then two twin core cables all cable tied together going into the DOL Starter. Any ideas on that one??

 

Thanks

 

Clive

As the current carrying capacity of 1.5mm wire is nearly 20A, it will do.

I'd say going to the trouble of sourcing a short length of 5 core cable is more trouble than it's worth. Appropriate for long runs where there's a need to clearly identify the cores, but Over The Top in this application. (Of course no harm in using multicore cable if you already have some.)

I'd just use a length of mains twin core and a length of mains three core held together with string or a length of spiral cable tidy (this example sold by Amazon). A manufactured item would likely use a wiring loom, ie 5 single core wires held neatly together with thin cord and routed to avoid hazards. Looms are usually made to size on a frame and fitted with terminators ready for assembly, but no reason not to make similar on the spot.

The most objectionable part of the circuit is the long wandering live cable connecting the safety interlock switches together. If it falls off, there will be a dangling shock hazard. You could reduce the risk by fixing the cable down firmly with clips, or even better by running inside a conduit. (Plastic conduit is used to protect mains cabling in homes.) A better answer is to operate the interlocks with low voltage. The interlocks would operate a contactor next to the control box, and the contactor would manage the mains. But as that involves more expense and complexity, I'd go with what you've proposed.

Health and Safety is about managing risk. You've spotted some risks with the original machine and are taking steps to reduce them, which is good! The proposed fix introduces some new electrical risks which need the same consideration. Basically earthing all external metal parts, and making sure adults, children, and animals can't touch a live wire, including the possibility that a live wire might vibrate loose, snag, or chafe. I think the last 3 risks are why the long run between interlock switches needs attention : I'd probably protect it with conduit or any other practical way of securing the wire safely. The end goal is to make the machine safer than before, not to meet the highest possible standards. (The way houses are wired would be unacceptable on a ship, because ship electricity involves mores risks. Wiring a home to nautical electrical standards is a waste of time and money because – for example – it's unlikely a home will ever be soaked in salt water, or have it's wiring storm tossed or shaken continuously by a massive Diesel. ) If the risks presented by this old machine are mitigated, that's good. No need to fit a fancy waistcoat.

Dave

 

Edited By SillyOldDuffer on 24/02/2020 10:05:02

[Clive B 1Participant @cliveb1]

Johnboy

“i would prefer motor supply separated from the control/E-Stop circuit”.

Can I ask you, why the preference?

[Clive B 1Participant @cliveb1]

Emgee / Johnboy

I’m going to apologise before I even ask this next question, can you take a look at the revised wiring sketch.

Am I right in assuming when you say “Remove the brown live to the motor from T1 (2) and terminate in T2 (4)
Wire a 1.5mm size link from T1 (2) to L2 (3)”

The new termination will be as I’ve indicated in Red for the motor live wire and the link wire should run as I’ve indicated in Blue and not where I’ve shown it in Green, the reason I’m asking is there are two terminals 2 T1??

[EmgeeParticipant @emgee]

Blue wire is showing correct connection, the other T terminals on the contactor have the 3 o/l legs connected.

Emgee

[Clive B 1Participant @cliveb1]

Sillyoldduffer

Thank you for your input, the cable to the interlock switches will be cable clipped to the underside of the table and are also set well back from the edge of the it behind the angle iron framework, so if I move the table about my hands will not be coming into contact with the wiring.

Clive

[Former MemberParticipant @formermember19781]

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[Clive B 1Participant @cliveb1]

Emgee

Thanks for clarifying the cable connections for me.

I may as well find out, Looking at the DOL picture Iv'e already posted, am I right in assuming the little square test button is so the overload coil can be tested periodically much the same as an mcb in a consumer unit is tested.

I can also see a small blue reset switch, is that to reset it after the test button has been pressed or indeed to reset it should the overload coil be activated at any time?

Clive

[Johnboy25Participant @johnboy25]

Clive…

it’s consider good practice to keep control and power separate and i’m being a bit old school 😳 The middle terminals are only the connections between the contactor and over load relay – no wiring should be connected to these terminals.

can’t get the marked photo to load up…

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