star delta motor .....extra stop/start....415v abb

[netblindpaul]

It seems that there is a lack of understanding of the difference between statute & civil law.

Also, why is it if someone suggests not complying with the latest version of BS7671 when they are doing an install or modification then it sees that they are wrong and must comply with this standard.
However, when it comes to electrical areas that are covered by other standards & statute law, people seem blasé in their interpretation and have no care for compliance with the statutory requirements?
I'll bet that most people who are working on electrical systems outside the scope of BS7671 do not hold copies of the standards & statutes to which they must be working?
In case you are not aware, in the event of a case, if you are not in possession of the relevant standard and statute to which you must be working then you will be deemed as non-compliant by the court.
Oh and the expert witness will make mashed potato out of you.

If you modify a machine control then you must upgrade it to current standards or, be prepared to face the music if it goes wrong, and, it may be a totally un-related incident.
If you are designing & implementing control system modifications then for your sake I hope you can prove competence & have suitable insurances in place, because due to FFI, you could easily be hit with a very large bill.

I can't understand the vehemence with which BS7671 is defended on this forum, and the total disregard for other more onerous requirements for electrical works, it is beyond my comprehension.

 

[chilliwilly]

Tell me then, to which document are you refering to that states that a 400v + controls are prohibited for use within the UK and Europe? It doesn't state in BS 7671 the NEC or the CEC or any document I am familiar with.

If you would care to read my previous comments you will see that I do use what ever voltage is present for extending, modifying, and designing, including 400v+, as the equipment is still readily available and manufactured by reputable companies such as crabtree, abb etc.

If what your saying holds any water, then my colleagues and myself will have to tell all our clients to switch of their distboards, cranes, lifts, catering, refrigeration, HVAC, and any 5 pin comando sockets supplying any fixed or portable equipment. Until they agree to have it upgraded to RLV or lower. And most of the sparks on here won't be able to fit or replace any tp mcbs, the country will come to a stand still.

 

[netblindpaul]

chillywilly,
You seem to have a total misunderstanding of what is considered a control system.
The NEC does not apply in the UK.
BS7671 does not apply to machinery & control systems.
Most of the descriptions you give above are power systems under BS7671, not control systems.
Do you even know what the standard for control systems is?
There are still limited allowed applications for 400V a.c. control, though they are few & far between.
You should if you are doing this work be stating in what cases this is allowed.
I know & pull clients on it regularly.
From your attitude this is going to end up in a slanging match which I am not prepared to enter.
If you are doing this work then you must have access to the relevant standards & statute law documents, so the requirements should be there in your reference library for you to refer to, I know they are in mine.
I can take this as far as you wish, but, I'm not willing for it to turn nasty, and the tone of your posts is going that way so I'm going to end my input to this thread here, as I am unwilling for this debate to turn into an abusive rhetoric on your part, which from where I am sitting it seems to be going.
I bid you good night and hope that your clients don't get into any bother as you could find yourself in big trouble.

I'll give you one final example, a client of mine had an accident with an FLT in their yard.
Their insurance company sent in investigators.
These investigators, found discrepancies with machinery elsewhere in the premises.
This resulted in the company being in breach of the terms of their insurance.
Thus the insurance company cancelled their policy forthwith and refused the claim as they were not in compliance with the terms of the policy and this could be proven, and was.
So, the company was then prosecuted for trading without insurance and there were several other issues.
There is more to this than meets the eye, the insurance non-compliances were nothing to do with the FLT incident.

Good Night & good bye.

 

[Darkwood]

Chilly you are confusing what is meant y control systems ...we are not talking about 3ph dist boards or commando style 400v plug and sockets when we work with these they are covered by the BS 7671 and are thus compliant ..... what we are discussing is machinery control systems that isn't covered by BS 7671, Lift systems have their own specific standards to to comply with too also out of the scope of the BS 7671, it may be the case that limit switches within the lift shaft may use 400v although not on the ones ive seen fitted, but the push buttons within the lift and call buttons will be ELV as they are prone to damage if not vandalism.

All the cranes new and old i work on have at max 110v at their pendants and due to this been at risk from getting damaged, caught up etc the modern cranes do use ELV.... i seen a few pendant cable lines ripped apart in my time and i would consider 400v swinging about at head height a dangerous senerio.


We are not talking about the LV side of any of your examples be it motor connections or heating elements but the control systems that operate this, considering even with 400v its still 230v to earth we do commonly have domestic switches etc that give the same potential to earth but the risk assessment in domestic has deemed this safe and where applicable measures are used like pull cords in bathrooms etc and zoning as well as rcd protection.

Lets try keep the theme of the debate to exporting control systems remotely to the control gear as was originally asked and not throw MCB's and plugs etc into the mix which are clearly nothing related to this debate.

 

[BrianDB9]

Statute law precludes 400V a.c. control at this point in time.
If you don't know this, leave it to those who do.

What law is that ? all this talk about 400 V being dangerous is crap , its standard practise in lots of places and it isn't voltage that kills you is it ?
Yes you can reduce the control voltage down to whatever you like but what are people saying all 400V motors need to be banned or something !

 

[chilliwilly]

My learned friend, I'm not confusing the voltage requirements of control with general enclosures, outlets, starters and other units. An enclosure is an enclosure and when bust open to expose 400v, is just as dangerous as 110v and would carry the same weight in court if there were evidence of neglect or incompetence. The pendant/wand that I changed on the pillar hoist the other day was a 415 volt control.

To push a button on to a 400v+ open or closed contact is no different to operating an mcb, isolator, or ellison type starter. In an old mill out Keighley way, the lift must be at least 60 years old, and I know for a fact the call button on the landing and inside the car, is 300v DC. I know the guy who services the lift and in his opinion there is nothing wrong with just because it has a higher control voltage than what is found on a modern high speed lift. And like me he has no intention of modifying it, he just carries on to repair and replace the contacts when they get worn.

There is also a hoist that is used about once a week for loading that in turn has 400v+ controls, as do the machine tools, compactor, and all the stops and gate/safety switches on a guilotine. And that is how they will stay until I am instructed otherwise.

 

[Darkwood]

What law is that ? all this talk about 400 V being dangerous is crap , its standard practise in lots of places and it isn't voltage that kills you is it ?
Yes you can reduce the control voltage down to whatever you like but what are people saying all 400V motors need to be banned or something !

Brian you are falling into the same trap as chilly in that you are confusing what is meant by a control system, we are not talking about the motor or the heating elements etc we are talking about the operating system which will have hands on interaction in most cases from a operator, its due to the very nature of this interaction with any machinery or control system that a risk assessment is needed to establish the risks and i would never consider it good practice in most cases to export control wiring for remote limits, sensors or push buttons at 400v.


Safety of Machinery-
EN 292 (ISO 12100 pts 1 & 2) Basic concepts, general principles for design
safety related parts of machinery and the general design principles.
(this references many other standards and outlines all basic principles)

EN 60204-1 (IEC 60204-1)
Electrical equipment of machinery -pt 1 general requirements.

(this is a very important requirement that outlines recommandations for safety related aspects of wiring and electrical equipment on machines)


Just a few EU Harmonized European Standards you really should know before you even attempt to fit and extra E-STOP or alter the control system of any machine.

 

[Darkwood]

My learned friend, I'm not confusing the voltage requirements of control with general enclosures, outlets, starters and other units. An enclosure is an enclosure and when bust open to expose 400v, is just as dangerous as 110v and would carry the same weight in court if there were evidence of neglect or incompetence. The pendant/wand that I changed on the pillar hoist the other day was a 415 volt control.

To push a button on to a 400v+ open or closed contact is no different to operating an mcb, isolator, or ellison type starter. In an old mill out Keighley way, the lift must be at least 60 years old, and I know for a fact the call button on the landing and inside the car, is 300v DC. I know the guy who services the lift and in his opinion there is nothing wrong with just because it has a higher control voltage than what is found on a modern high speed lift. And like me he has no intention of modifying it, he just carries on to repair and replace the contacts when they get worn.

There is also a hoist that is used about once a week for loading that in turn has 400v+ controls, as do the machine tools, compactor, and all the stops and gate/safety switches on a guilotine. And that is how they will stay until I am instructed otherwise.

The lift as already mentioned before has its own special regulations and standard to comply to of which i cant comment and as lift engineers they will hopefully be fully aware of and work or repair the lift within these standards.

The issue im sensing here is you seem to be on the mind set that if you work on an existing machine, crane hoist etc that may be design under past regulation and directives that you can leave it as such and just do the necessary but its the case that you need to do a risk assessment and decide whether a hazard exists do to its out-dated design ....simply replacing a pendant on a crane using the existing control set-up of 400v to pendant is in my mind short sighted.....we are talking about a cable and pendant that routinely gets hands on use and most likely takes alot of knocks.....so the cable splits by the pendant entry and the next guy using it is killed by the 400v ...how will you stand in court as you fitted the pendant because you'll be the first to have to explain why this wasn't seen in a risk assessment and im afraid saying if you quoted for the necessary alterations they wouldn't pay and you'd loose to someone else who would undercut you wont help you in court.

Yes im fully aware 400v exported controls are present within alot of dated machinery but when im told to make alterations or additions i include for any necessary updating to meet present standards, a one on one with the client expressing both my responsibilty and his own to his employees usually is enough and if not i wont put myself in that position.


Check this thread i started not long ago... 3 other electricians tried to repair it but failed when i came to it i knew i could get it going but it fell far short of requirements and ended it stripping the machine and starting again pic posted further on in thread.http://www.electriciansforums.net/c...uite-often-promised-tony-i-took-few-pics.html <--click link

If i repaired that board and even fitted the door back on the minute this deathtrap injured someone the responsibilty would be on my shoulders.

 

[chilliwilly]

I don't want you to think that I'm being cocky or unpleasant, but I fully understand and partially agree in what your saying, but can you give your proffesional opinion with the following case senarios...

1. A multicore with 415v to a pendant/wand, and a 5 core lead with 415v supplying a fixed item or portable equipment being used in the same environment.

2. Operating a switch, lever or a button that operate contacts that make or break 415v coils and other ancilliaries or loads.

3. Operating my roller shutter door from a 415v starter with no neutral to convert to 240v or lower, operating a lift call or car button with 300v DC or 415v across the contacts behind the button, and operating a TP thermostat on a catering appliance that switches elements and motors direct on line with contactor,and in turn has high limit stats in enclosures having surface contact temperatures of at least 180 deg c.

4. A 4 HP+ compressor operating a TP high limit switch to either stop the motor or operate a clutch when satisfied.

5. Replacing a gate or limit switch on an existing machine or plant, changing a mains board following a EICR and leaving code 3 departures only as reccomendations and noting them on the EIC?

6. A building site having temporary supplies from trannies and RLV cables being run over by mobile plant and the like.

In the case of the pendant/wand they should be assessed for risk from mechanical damage causing insulation failure and exposing live parts, I fully agree. Then if the assessment is found to indicate potential for danger, a reccomendation needs to made for another selection of containment for the cable, with a regular visual inspection. As would be the case for any other cable containing ELV RLV or LV. Or in your case a elv as a get out of jail free card, (but with no guarantee of defence if resulting in permanent damage or death to users).

But this can lead to total replacement of the whole system, in the event of long cable runs trannies supplying elv might not be suitable. Or a motor starter with remotes with only 3 ph and earth being fed to and from it. And any customer of mine will want to see evidence of regulation and or documentation to back up my decision to carry out such extremes in the event of replacing a coil, button and contact, thermostat, ellison external starter, etc.

 

[chilliwilly]

Yes that panel is a total mess, I used to come across stuff like that in foundries, and rubber compound plants, and at Thomas Faucettes in Castleford. Now that place was a death trap, how anyone wasn't killed in that place can only be known by a devine entity. I think they were still open the last time I drove past.

I can see where your coming from, but even if that was RLV, it would still constitute a code 1 departure. Clearly condemning the person arising in the event of a loss in resulting adding or replacing any parts to it without first removing the danger. My risk assessment of that would be to assess the risk of it being damaged again and place a crash barrier around it, or have it moved in a safer location. It could have been another enclosure such as a mains board with 400v + inside it.

But then again who ever decided to place it there either did or didn't exercise reasonable care within their design. I'll never know or find out.

The panel that I'm building at the moment is for a conveyor system for a small polymer factory, that is enclosed by barriers and guards incorporating gate switches. The exisiting system is a 415 v control, so I am simply replacing it because their is no more risk to users than what there already is. The only difference with voltage within the "D" connectors is the ELV to interface an omron plc that controls the process, and will switch the panel. And 4 of the motors are 100v connected in series. Yes that's right, 100v motors connected in series and wound to a point that they are 100% balanced regards to voltage and current, so they all run at synchronous speeds and don't stretch or compact the extruded polymer when its conveying on the 4 belts. An idea that some one came up with before my time, because they couldn't afford invertors to control the speed of the motors.

 

[chilliwilly]

chillywilly,
You seem to have a total misunderstanding of what is considered a control system.
The NEC does not apply in the UK.
BS7671 does not apply to machinery & control systems.
Most of the descriptions you give above are power systems under BS7671, not control systems.
Do you even know what the standard for control systems is?
There are still limited allowed applications for 400V a.c. control, though they are few & far between.
You should if you are doing this work be stating in what cases this is allowed.
I know & pull clients on it regularly.
From your attitude this is going to end up in a slanging match which I am not prepared to enter.
If you are doing this work then you must have access to the relevant standards & statute law documents, so the requirements should be there in your reference library for you to refer to, I know they are in mine.
I can take this as far as you wish, but, I'm not willing for it to turn nasty, and the tone of your posts is going that way so I'm going to end my input to this thread here, as I am unwilling for this debate to turn into an abusive rhetoric on your part, which from where I am sitting it seems to be going.
I bid you good night and hope that your clients don't get into any bother as you could find yourself in big trouble.

I'll give you one final example, a client of mine had an accident with an FLT in their yard.
Their insurance company sent in investigators.
These investigators, found discrepancies with machinery elsewhere in the premises.
This resulted in the company being in breach of the terms of their insurance.
Thus the insurance company cancelled their policy forthwith and refused the claim as they were not in compliance with the terms of the policy and this could be proven, and was.
So, the company was then prosecuted for trading without insurance and there were several other issues.
There is more to this than meets the eye, the insurance non-compliances were nothing to do with the FLT incident.

Good Night & good bye.

Goodbye.

 

[Knobhead]

An old saying comes to mind,
“There’s none so blind as he who will not see.”

At lease the lift maintenance guy seems to have sense in CW’s post. The lift system may be old but it can not be altered without the correct design procedure. This I would always put in the hands of the manufacturer. Up until the 80’s Ellison OCB’s would still be fitted to many industrial lifts as they would be tied in to the ultimate limit. Woe betide anyone that altered the control as there would be a major arse kicking party when the 6 month insurance inspection was done.

Lift manufacturers offer training courses which are well worthwhile. One that is worth doing is emergency rescue procedures. All the site electricians had to do this at one company I worked for. It came about when I got stuck in one of the lifts, I was the only person on site trained in lift rescue!

 

[Guest111]

it,s all about understanding the laws related to what you are working on,ignorance is no defence, and there is the old one of last man to work on it carries the can.As others have said insurance companies will look anywhere to get out of paying a claim these days,sometimes it,s better to walk away than have something hanging over you that will come back to haunt you years later.

 

[chilliwilly]

An old saying comes to mind,
“There’s none so blind as he who will not see.”

At lease the lift maintenance guy seems to have sense in CW’s post. The lift system may be old but it can not be altered without the correct design procedure. This I would always put in the hands of the manufacturer. Up until the 80’s Ellison OCB’s would still be fitted to many industrial lifts as they would be tied in to the ultimate limit. Woe betide anyone that altered the control as there would be a major arse kicking party when the 6 month insurance inspection was done.

Lift manufacturers offer training courses which are well worthwhile. One that is worth doing is emergency rescue procedures. All the site electricians had to do this at one company I worked for. It came about when I got stuck in one of the lifts, I was the only person on site trained in lift rescue!

If there's nothing to see then you might as well be blind, not so much as a blur but only a muffled sound.

The engineer was only in the lift car the other day changing a worn light switch on the car control panel that switches 240v! Naughty boy. Didn't even bither to test the em light, maybe the 240v aspect confused him into thinking there were a double standard?

I did the lift rescue course as well but I would still change like for like regarding buttons, contacts, switches, pendants and the like. Until there is concrete evidence that I'm causing potential danger and liable to prosecution in the event of a loss arising from my actions of connecting accessories and controls to 110, 240, and 400+v.

The niccy will be stood in the doc with me should any such occasion arise, and I will have to submit my niccy endorsed mw or eic as my defence.

The ellison unit wasn't a dashpot type isolator it was a starter for a 300 horse motor that I had rebuilt because my customer didn't have the money to have a panel built that switches restistor banks. Which I issued a mw cert to confirm it was safe to use.

How did you manage to rescue your self when you got stuck in the lift when you was the only person on site qualified and licenced to rescue people out of lifts? Let me gues you removed the car control panel a nd then decided you weren't going to touch anything becsuse the voltage was higher than than 24 v and you thought you was breaking the law. And decided to climb out of the top, but the realised that the containment system contained voltages higher than 24v and jumped back in thw car. And then shouted help or phond the brigade.

 

[Knobhead]

I didn’t get myself out! 5 f***in hours waiting for rescue.

Is this 300HP Ellison unit an OCB or DMO unit? Because if it is you will find yourself in the mire if anything goes wrong.
Have a look for the HSE directive on DMO switches. Makes interesting reading.

Enjoy you’re holiday.

 

[Darkwood]

I wouldn't rely on the Niceic as there are only viewing any works that come under the 17th and as you work outside of the scope of these regs they wont stand in any doc with you, ive taken them on a panel build in the past and he didn't know his rectum from his elbow ... his just checked the isolator to machine and supply was correct .....quietest ive seen him in ages they are usually full of questions.

 

[Darkwood]

I didn’t get myself out! 5 f***in hours waiting for rescue.

Is this 300HP Ellison unit an OCB or DMO unit? Because if it is you will find yourself in the mire if anything goes wrong.
Have a look for the HSE directive on DMO switches. Makes interesting reading.

Enjoy you’re holiday.

I think you were set up Tony ..... although I cant understand why? I mean your shy and reserved; its not like you to say what you think

 

[chilliwilly]

Hello my learnrf friend, hope you have had a good day? Where will I find that standard that you referred to in your other post?

The niccy inspector that used to inspect my work is ex industrial and beleive you me he knows his stuff, but no mention of any other standard relating to limitrd use of voltage ranges used only for control circuits. Then Tony Harrison took over from him, and he seemed to knpw his stuff as well.

I am in the process of re applying for membership with the niccy, and will be intersting if they snag 400v + control voltage?

 

[chilliwilly]

I didn’t get myself out! 5 f***in hours waiting for rescue.

Is this 300HP Ellison unit an OCB or DMO unit? Because if it is you will find yourself in the mire if anything goes wrong.
Have a look for the HSE directive on DMO switches. Makes interesting reading.

Enjoy you’re holiday.

I don't know as the decal/badge was missing, but its still painted orange and in very good condition if that helps?

If I get away anytime, I will send you a post card with wish you was here and all that, but you will have let me know whete to send it?

Thanks for coming.

 

[Darkwood]

Hello my learnrf friend, hope you have had a good day? Where will I find that standard that you referred to in your other post?

The niccy inspector that used to inspect my work is ex industrial and beleive you me he knows his stuff, but no mention of any other standard relating to limitrd use of voltage ranges used only for control circuits. Then Tony Harrison took over from him, and he seemed to knpw his stuff as well.

I am in the process of re applying for membership with the niccy, and will be intersting if they snag 400v + control voltage?

Have a browse at this Rockwell have simplified it and generalised it but I cant give a definite directive as its covered by category and risk assessment as to the nature of the control voltages etc also a lot of machinery may come under its own specialised EN codes of practice.http://literature.rockwellautomation.com/idc/groups/literature/documents/rm/shb900-rm001_-en-p.pdf It also gives relevant EN - code references throughout the PDF that may apply to work you encounter. The list is endless and im not at home to pull out any particular code but hope it highlights what you need to do when repairing or upgrading machinery....

 

[KAS1]

I used to hate to see / work on 415v control circuits especially remote stop/start stations, feel much happier with 24v or 110v control circuits much safer IMO, seen people fault finding on live remote stop/starts with a multi meter and reading 220v to earth on most of the terminals and getting really confused not even thinking that 400/415volts were present lol

 

[Darkwood]

I used to hate to see / work on 415v control circuits especially remote stop/start stations, feel much happier with 24v or 110v control circuits much safer IMO, seen people fault finding on live remote stop/starts with a multi meter and reading 220v to earth on most of the terminals and getting really confused not even thinking that 400/415volts were present lol

Its no easier at 24dc if negative hasn't been grounded... can get allsorts of confusing conflicting readings if your new to it.

 

[silva.foxx]

Learned ex-ridgetile rider

Here's one reg for you EN 60204-1:2006+A1:2008 Electrical equipment of Industrial machines.

"9.1.2 Control circuit voltages
The nominal value of the control voltage shall be consistent with the correct operation of the control circuit. The nominal voltage shall not exceed 277 V when supplied from a transformer."

EN 60204 also specifies that all but very simple control circuits should be supplied from a transformer or isolated DC PSU.

Line - neutral 230V or line - line 400V control voltage can be used where there is only one contactor with no control functions outside its immediate enclosure. (E.g. a simple individual enclosed starter... no external stop/start pushbutton stations)

http://infoplc.net/files/documentacion/seguridad_normativa/infoplc_net_200941458485281.pdf

Whether it is relevant to churches or car hoists is not my concern, but as Darkwood and NBP have guided you toward... repairing a control system by replacing a component like for like on whatever voltage you like is fine as long as it is to original spec... but modifying a control system means you need to fall in line with the relevant standards.

It's also a bit pathetic to say that everything at or above 400vac is law breaking... you may want to re-read your opening rants and tone down your input as it reads un-necessarily aggressive. Be polite, positive and professional to keep it a good place for healthy debate and fun.

.

 

[Knobhead]

Any ungrounded system will cause confusion. Especially when you get an earth fault on the supposed live line.

 

[Darkwood]

Cheers for the pdf Silva..... I had earlier referenced where to find the relevant machine safety standards but wasn't in a position to look up the specific blurb as im working away, you saved me a job when I return home

 

[Engineer54]

Cheers for the pdf Silva..... I had earlier referenced where to find the relevant machine safety standards but wasn't in a position to look up the specific blurb as im working away, you saved me a job when I return home

I am getting the impression you'll still be just bashing your head up against a brick wall here mate!! ...lol!!

 

[chilliwilly]

Learned ex-ridgetile rider

Here's one reg for you EN 60204-1:2006+A1:2008 Electrical equipment of Industrial machines.

"9.1.2 Control circuit voltages
The nominal value of the control voltage shall be consistent with the correct operation of the control circuit. The nominal voltage shall not exceed 277 V when supplied from a transformer."

EN 60204 also specifies that all but very simple control circuits should be supplied from a transformer or isolated DC PSU.

Line - neutral 230V or line - line 400V control voltage can be used where there is only one contactor with no control functions outside its immediate enclosure. (E.g. a simple individual enclosed starter... no external stop/start pushbutton stations)

http://infoplc.net/files/documentacion/seguridad_normativa/infoplc_net_200941458485281.pdf

Whether it is relevant to churches or car hoists is not my concern, but as Darkwood and NBP have guided you toward... repairing a control system by replacing a component like for like on whatever voltage you like is fine as long as it is to original spec... but modifying a control system means you need to fall in line with the relevant standards.

It's also a bit pathetic to say that everything at or above 400vac is law breaking... you may want to re-read your opening rants and tone down your input as it reads un-necessarily aggressive. Be polite, positive and professional to keep it a good place for healthy debate and fun.

.

Thank you for the link, I will read and consider what it states, I am not intending to be aggressive, I am replying to the same egregious tones as the other abrupt posters.

There's only you an darkwood that have shown that you are gents by offering advice and support, and not like the cocky know it all, "that's a fact because I say so because I'm self proffessed" attidudes from some of them on here.

At the end of the day if someone stands on my toes, I will stand on theirs.

In the meantime thank you again for the link.

 

[Knobhead]

Read and consider would indicate you don’t intend to take on board what you have been told. That decision is yours.
Now think on you’re opinions and actions if things go wrong.
You’re attitude to safety is now a matter of record due to this site. You no longer have the recourse of ignorance of the law as a defence.

Sleep well dear child. The demons of the night are yet to wake and haunt you’re dreams. Sleep well.

 

[chilliwilly]

Read and consider would indicate you don’t intend to take on board what you have been told. That decision is yours.
Now think on you’re opinions and actions if things go wrong.[/SI
You’re attitude to safety is now a matter of record due to this site. You no longer have the recourse of ignorance of the law as a defence.



Sleep well dear child. The demons of the night are yet to wake and haunt you’re dreams. Sleep well.

See what I mean?

 

[KAS1]

Not so dangerous though lol

Its no easier at 24dc if negative hasn't been grounded... can get allsorts of confusing conflicting readings if your new to it.