RCDs and cable dimmensions

[dave_h]

Hi everyone,

Im in the process of upgrading my brew pots to immersion elements (from over the side elements) and have a couple of questions.

I have been using two portable RCDs (16 Amp which trips at 30mA)



Am I correct in thinking that these will be sufficient? I do not have a RCD in my main house board. I read some conflicting stuff that 30mAmp would still kill you but all of the rail mounted RCDs ive seen seem to have the same trip level.

Also, Im currently using 3G 1.5mm extension cables, and ive noticed that these are a little warm to touch after an hour, would it be worth upgrading to 3G 2.5mm? Will be using them upto 16Amp.

SSRs to control the boil rate, Im planning on getting them rated to 40Amp.

Thanks in advance

Dave

 

[MitchD]

Hi everyone,

Im in the process of upgrading my brew pots to immersion elements (from over the side elements) and have a couple of questions.

I have been using two portable RCDs (16 Amp which trips at 30mA)

RCD.jpg

Am I correct in thinking that these will be sufficient? I do not have a RCD in my main house board. I read some conflicting stuff that 30mAmp would still kill you but all of the rail mounted RCDs ive seen seem to have the same trip level.

RCD's work in two ways; time and current. While the cheap plug in units will trip when leakage is over 30ma they very rarely trip in the required time 300ms. So while 30ma will kill you the design is to trip the RCD before the amount of time required to kill you.

Also, Im currently using 3G 1.5mm extension cables, and ive noticed that these are a little warm to touch after an hour, would it be worth upgrading to 3G 2.5mm? Will be using them upto 16Amp.

Cabling is designed with a working temperature of 60c-110c when used in 40c ambient temperature, 1.5mm of a reputable brand can take 16a.

SSRs to control the boil rate, Im planning on getting them rated to 40Amp.

Probably over kill but it will work

Thanks in advance

Dave

 

[TheWiggman]

Do you understand the purpose of RCDs? They are designed to protect someone from getting electrocuted by detecting when there is a path between the source and earth. They aren't designed to protect equipment. Not trying to be patronising, just making sure you have the right intent because if you are able I would install the RCD at the mains instead of locally at the brew system.

Getting larger SSRs isn't a bad idea because they will run at a lower temperature than a 25A under the same current. It's the difference of about $1 from China, and depending on how you're intending to mount it might be a worthy investment.

 

[Camo6]

I was taught that around 50mA is enough to kill you, hence the 30mA limit, but it depends on the path taken through your body, skin resistance at the time, heart condition etc. Regardless to say, no amount of AC current through you would be nice.

What are the sizes of the new elements? If they're more than 2400W you're pushing the recommended limits.

Also, do the plug in RCD's also trip with current overload or is it just their rating? I assume they do but they look a bit like cheap ebay jobbies. If not I'd want to know that my circuit protection was adequate too. Do you have circuit breakers at the board or old style ceramic fuses?

 

[DU99]

the leads do they a straight run and have no loop in the them

 

[spog]

If its getting warm it's being stressed = danger.

 

[dave_h]

Many thanks for all the replies,


TheWiggman

"Do you understand the purpose of RCDs? They are designed to protect someone from getting electrocuted by detecting when there is a path between the source and earth. They aren't designed to protect equipment. Not trying to be patronising, just making sure you have the right intent because if you are able I would install the RCD at the mains instead of locally at the brew system."

Not patronising at all, I did read somewhere that most of the plug in RCDs were more for equipment safety rather than personnel so I was a little confused. I have been thinking of getting some RCDs put into the main board so might just do this



Camo6

"What are the sizes of the new elements? If they're more than 2400W you're pushing the recommended limits.
Also, do the plug in RCD's also trip with current overload or is it just their rating? I assume they do but they look a bit like cheap ebay jobbies. If not I'd want to know that my circuit protection was adequate too. Do you have circuit breakers at the board or old style ceramic fuses? "

I have not decided on the elements yet, I was thinking of these two

http://www.aliexpress.com/item/AC220V-2000W-Metal-Electric-Heating-Tube-Water-Heater-Element-Silver-Tone/32411921460.html?spm=2114.01020208.3.153.vyqMZB&ws_ab_test=searchweb201556_3,searchweb201644_5_79_78_77_82_80_62_81,searchweb201560_2

http://www.aliexpress.com/store/product/240V-2500W-Immersed-Foldback-Heating-Element-Screw-In-1-INCH-NPT-Thread-Tubular-Heating-Element/1862595_32546357152.html

Im based in Sweden at the minute and have 230V (223V when tested yesterday), I have been using a 3.2KW over the side element without any issues on a 16Amp circuit. I calculated 230V at 16Amp max was 3.6KW

Currently also trying to determine what their watt densities are and if they are low enough.

I have old school ceramic breakers, but also have three phase power (with 3 phase to single adapter), so each brew circuit is on its own with nothing else!

The RCDs I have are Everflourish EMP200S

• An integrated earthed socket, with child protection IP44 for operation in indoor or outdoor use (outdoors or in damp areas, observe the operating position) Switching Current: 30mA switching time <30ms Bipolar disconnection
• Can be connected to grounded mains power socket, 230V ~ / 50Hz Max. Total connected load 3680W (230V ~, 16A) resistive load

So they are supposed to trip within 30ms so should be ok? But they dont have overload protection so would have to rely on the fuses.


DU99

"the leads do they a straight run and have no loop in the them"

They are quite straight, they are not really hot but warmer than the surroundings, just thinking that if Im going to make some cables up (as I will put a PWM and SSR in ) then I could go a cable with more safety margin in. Ambient temps are not really too much of a problem here (no 40C here, currently -6C.......).

Thanks for the help guys, Im planning on getting an electrician to check it all out before use but its good to get things as close to right as I can before I get one out.

 

[Diode]

Cabling is designed with a working temperature of 60c-110c when used in 40c ambient temperature, 1.5mm of a reputable brand can take 16a.

Are you F^&^%$G serious

I hope those cables are very short

You need to spend a lot more years in the game my friend

 

[MitchD]

Cabling is designed with a working temperature of 60c-110c when used in 40c ambient temperature, 1.5mm of a reputable brand can take 16a.

Are you F^&^%$G serious

I hope those cables are very short

You need to spend a lot more years in the game my friend

Thank you for your insightful responce, do you care to elaborate or provide some assistance to the OP?

 

[Pokey]

The temperature that will start to damage your cables will depend on what they are insulated with. Personally if they are warm I would use bigger cable.
If you're looking at putting in RCDs at the board get the breakers changed as well, new breakers are better than old ones and significantly better than rewireable fuses.

 

[TheWiggman]

Big entrance there by Diode

 

[Diode]

Ttry running 1.5mm with 16A over say 30-40m and see how you go. Betcha it gets warm

 

[burrster]

What Diode is trying to say is the cable size is not the only factor in how much current a cable can carry. Cable length and how thermally insulated it is play a big part too. 16A through 1.5mm cable is not the best idea in my opinion and using 2.5mm cable would be a better/safer option.

 

[Diode]

15A cct requires min 2.5mm

 

[Camo6]

Cabling is designed with a working temperature of 60c-110c when used in 40c ambient temperature, 1.5mm of a reputable brand can take 16a.

Nothing untrue about this statement. Flex wiring in 1.5mm2 has a max recommended current rating of 16A. The OP never mentioned fixed cabling. Certainly de-rating factors still have to be considered but MitchD didn't allege otherwise. Hardly worthy of such a vehement reply Diode but eloquently rephrased by Burrster.

On the subject, try and find an extension lead in any hardware store with a greater diameter than 1.5mm2. Even the heavy duty type are generally 1.5mm2 it's just that they use a heavy duty insulation. I've been told flex has a greater current carrying capacity than stranded or solid due to the greater surface area and the skin effect in an AC circuit but I'll leave this to the experts. But the old adage bigger is better is generally true in this regard.

If I was the OP I'd be ensuring my circuit protection and RCD devices were all up to scratch and upgrade to 2.5mm2 wiring. Beats burning your house down.

 

[spog]

15A cct requires min 2.5mm

The diagrams you have posted means bugger all to many here,including dumb bastards like me.
Could you please put your explanation in dumb ******* words for us.
Please understand I'm not having a go at you but electricity is lethal ( oh so many comments in other posts) so others may benefit from advice.
And now this thread is likely to go off the rails, re: get a sparky get a sparky......

 

[SBOB]

The diagrams you have posted means bugger all to many here,including dumb bastards like me.
Could you please put your explanation in dumb ******* words for us.
Please understand I'm not having a go at you but electricity is lethal ( oh so many comments in other posts) so others may benefit from advice.
And now this thread is likely to go off the rails, re: get a sparky get a sparky......

the symbols in his signature have nothing to do with wire current ratings or RCDs

 

[spog]

Ahh thanks,see I am a dumb *******.

 

[dave_h]

Thanks guys,

My cables are around 5m extension type, store bought, they are not as well insulated as some of the longer/more industrial ones I have. I will make some cables up with 2.5mm for use with SSRs. Cant see any plugs rated higher than 16Amp but will talk to my sparky

I will get a sparky to put in some RCDs when he has a look at my elements/pots.

These are the type of fuses I have in my main board.


After having a sparky out for something else I said that I wanted to upgrade them and he recommended not to, cant remember his reason. He thought it was a good idea to put in some RCDs anyhow.

But party back to one of my original questions, are these portable RCDs any difference to the rail mounted ones, or do the rail ones trip faster.

Ive also read somewhere that you should not have two RCDs in the same circuit for some reason, but can talk to the sparky.

Thanks

Dave

 

[Camo6]

I thinking having more than one RCD in a circuit can cause nuisance tripping but I've never experienced it with my controller.

If those RCD's are of decent quality and have the same ratings then they should function the same as one in a switchboard except obviously it'll only isolate downstream from the unit. Most worksites run on portable rcd's until the power is commissioned.