Residual Current Device (RCD)

[GordMay]

Originally Posted by scotte

The good news is they (ABYC) haven't (yet) moved forward with AFCI over GFCI. The bad news is the "yet".

Why - what have you got against fire prevention?

When, and if, Arc-fault requirements are effected, they will likely be in ADDITION to Ground-fault protection - not instead of.

An Arc-Fault Circuit Interrupter (AFCI) is a device, with an integrated processor which recognizes the unique current and/or voltage signatures associated with arcing faults, and functions to de-energize the circuit when an arc-fault is detected. An arc is a high temperature luminous electric discharge across a gap.

Problems in home wiring, like arcing and sparking, are associated with more than 40,000 home fires each year! A 1994 insurance company study determined that over 33% of fires in nearly 700 cases were from arcing faults. Arc faults most often occur in damaged or deteriorated wiring and cords, creating very high temperatures which can ignite nearby combustible stuff (ie: bedding).

North American electrical codes* now require that all branch circuits that supply 125 volt, single-phase, 15 and 20 ampere receptacle outlets installed
in dwelling unit bedrooms shall be protected by an Arc Fault Circuit
Interrupter(s).

While both AFCIs and GFCIs are important safety devices, they have different functions. AFCIs are intended to address fire hazards; GFCIs address shock hazards. An AFCI can be used in conjunction with GFCI protection to provide both arcing fault protection as well as 5mA ground fault (people) protection. A common way to provide both types of protection is to use an AFCI circuit breaker and a GFCI receptacle. AFCIs can also incorporate 5mA GFCI protection into the same package.

* The 2008 NEC brought significant changes into the AFCI world, concerning device itself (more types of fault monitored) and expanding greatly areas of its application (required in more rooms).

[RBEmerson]

TNX for the ABYC posting!

[bobfnbw]

If one has a RCBO 15 amp breaker at the panel and all 120v outlets are wired to that, do you still need a GFCI outlet? Would they play nice together ?
When I rewire I plan on installing 2 AC circuits, port and starboard with BSS RCBO breakers, with Inverter backup thru this side of the ac circuit. It has 5 ma tripage, so why would a additional GFCI outlet be required ?

15A Single Pole Residual Current Circuit Breaker (RCBO-GFCI) - PN 3100 - Blue Sea Systems

thanks.
Bob

[GordMay]

No - you won’t require GFCI receptacles, when you utilize the BSS RCBO breakers at the panel. Your assumptions are correct.

The Blue Sea Systems #3100 is a 15A SP GFCI Breaker (5 mA “people protector”), suitable as a ground fault branch circuit breaker.

The BSS 3102 is a 30A 2P RCD Breaker (30 mA “whole boat protector”), suitable for use as a main breaker. Tho’ whole boat protection is not required by ABYC (North America), the Europeans do require them.

Both breakers provide the required overload protection.

[chala]

Extemp.
RCD as described are found in vessels where they monitor essential circuits. For good reasons they only warn of current leakage but do not disconnect. In Australia RCBO are listed as RCD, confusing. They have been mandatory on shore supply for some time now and can be found on newer marina's. But The Australian Wiring Rules change all the time and I will not be surprised if they become mandatory on boats. My boat is equiped with a 30mA and I am happy with that. Australian RCD are similar in value to the one quoted in the threads: 10mA max 40mS, 30mA and 100mA max 300mS. Let not forget that leakage current is cumulative. 10mA leakage on the fry pan plus 10mA on the freezer leave 10mA on a 30mA RCD.
Beware of 3 phases RCD they are dangerous.
Beware also that in any two poles switch if the neutral reconnect late or not, damage can be done to fancy equipment.

[bobfnbw]

Thanks Gord.
A llittle people protection around 110v is good...no ?

[Extemporaneous]

Originally Posted by chala

Extemp.
RCD as described are found in vessels where they monitor essential circuits. For good reasons they only warn of current leakage but do not disconnect. In Australia RCBO are listed as RCD, confusing.

In my boat all circuits are essential, if for no other reason, because they carry potentially dangerous electricity. I want to do what I think is reasonable to make it as safe as possible.
And yes, and I'm confused easily. I have main breakers and so originally was looking for just an RCD. I've given up on that approach and will get an RCBO with its own housing, I'll take the mains out of my panel and use the space for additional breakers.

Originally Posted by chala

Extemp.
My boat is equipped with a 30mA and I am happy with that. Australian RCD are similar in value to the one quoted in the threads: 10mA max 40mS, 30mA and 100mA max 300mS. Let not forget that leakage current is cumulative. 10mA leakage on the fry pan plus 10mA on the freezer leave 10mA on a 30mA RCD.

Glad to here first hand that someone with the setup is happy with it. Got the cumulative part, thanks.

Originally Posted by chala

Extemp.
Beware of 3 phases RCD they are dangerous.

Don't have 3 phase, know all electricity is dangerous, is there something you can share particularly regarding the 3 phase RCD combo that makes it more dangerous?

Originally Posted by chala

Beware also that in any two poles switch if the neutral reconnect late or not, damage can be done to fancy equipment.

Was not aware of this one, can you explain or send me somewhere specific to read?

Thanks and Best Regards,
Extemp.

[chala]

OK I try in script:
Time frame: Vietnam War, fear of East Timor becoming communist.
Location: North Australia, Australian defenses forces, Computer section.
Job: servicing of a static UPS a novelty in these days.
Government civilian serviceman change manual switch from UPS to mains.
Inrush of officers panic station 1: “what have you done we have lost three computers.”
Matter of National defense big boss’s arrives, big boss try to understand: “ but the only thing we did was to operate the switch” and operate switch.
Inrush of officers panic station 2: “we have lost another three computers, nobody touch anything anymore we have only two left” Big boss look very sorry and ask if officers can comment on the nature of the damage “sorry National defense not allowed to comment”. Big boss ask if he can have a look “sorry highly restricted area, not allowed”. After few hours of discussion it was discovered that the space under the raised computer floor was not a highly restricted area and that I, the middle boss and the serviceman where allowed to crawl through the space and look at the damage through some ventilation slots. What I saw was neat looms of small earth wires and adjoining circuit boards totally melted. During the few milliseconds it took to operate the switch, the neutral having open first, the active found a path to earth and destroyed everything.
In a 3 phases unbalanced load without a neutral, a 240V appliance may have a voltage above or below 240V in OZ. Yes there is Standards regarding the manufacture of switches. Dust, vermin or insects can also cause bad contacts operation; they sit on the top of the contacts, when the contacts open they fall between the contacts.
There is nothing like practical experience for learning.

[Extemporaneous]

Originally Posted by GordMay

UL Class “A” (4-6 mA) GFCI Receptacles are rated for operation at 50 - 60 Hz input.

A GFCI works by using a* summing toroid sensing coil (DCT - Differential Current Transformer). Both the "hot" line leaving the breaker and the “neutral” line returning to the breaker travel through the DCT/toroid. The DCT/toroid then sums the current in both of the wires and if more current leaves than returns the breaker will trip. At 60 Hz, the breaker will trip when approximately 5 mA of current does not return to the circuit breaker. Current not returning via the neutral represents the hazardous condition (including a ground fault) that a GFCI is designed to protect against, following an inverse time curve [ie: at 6mA; UL943 requires the GFCI to interrupt within 5594msec (5.6 seconds), at 25mA it must interrupt at 726msec (0.73 seconds) and etc.]

* May actually be 2 separate DCTs.

Originally Posted by GordMay

No - you won’t require GFCI receptacles, when you utilize the BSS RCBO breakers at the panel. Your assumptions are correct.

The Blue Sea Systems #3100 is a 15A SP GFCI Breaker (5 mA “people protector”), suitable as a ground fault branch circuit breaker.

The BSS 3102 is a 30A 2P RCD Breaker (30 mA “whole boat protector”), suitable for use as a main breaker. Tho’ whole boat protection is not required by ABYC (North America), the Europeans do require them.

Both breakers provide the required overload protection.

Please see attached.
Does anyone know where (in North America) I can get a RCD Breaker that will work for both 50 Hz and 60 Hz?

Thanks,
Extemp.

[GordMay]

Originally Posted by Extemporaneous

Does anyone know where (in North America) I can get a RCD Breaker that will work for both 50 Hz and 60 Hz?
Extemp.

No.

Sorry; my quoted post was misleading - Breakers are only rated for 60Hz OR 50Hz operation - not and/or both frequencies.

North American* GFCI & AFCI devices are rated for 60 Hz operation only. Differing frequencies can affect the thermal, magnetic and short-circuit characteristics of circuit breakers.

* The continuous current rating of a circuit breaker is defined by the National Electrical Manufacturers Association (NEMA) as:
“The maximum direct current or rms current in amperes at rated frequency which a device or assembly will carry continuously without exceeding the specified limits of observable temperature rise.”

[Extemporaneous]

Originally Posted by GordMay

No.
Breakers are only rated for 60Hz OR 50Hz operation - not and/or both frequencies.

North American* GFCI & AFCI devices are rated for 60 Hz operation only. Differing frequencies can affect the thermal, magnetic and short-circuit characteristics of circuit breakers.

* The continuous current rating of a circuit breaker is defined by the National Electrical Manufacturers Association (NEMA) as:
“The maximum direct current or rms current in amperes at rated frequency which a device or assembly will carry continuously without exceeding the specified limits of observable temperature rise.”

Dam,
It's getting hard to stay flexible in my system.
Gord,
Do you know if there is a predictable relationship when using a 60 Hz breaker and/or RCD Breaker with a 50 Hz supply and that it would just act out of spec, but consistently and predictably, but safely?

I can't see every North American boat going to Europe being unsafe, but what do I know (Don't answer that). I'm thinking that the 60 Hz RCDB may just trip at a higher value (less sensitive) with a 50 Hz supply but that's just a WAG.

Is there another strategy that I should be following?

Let me know if you can.

Thanks,
Extemp.

[CharlieJ]

Extemp-I doubt if you will find any circuit breaker manufacture who will back his products if you use them outside of the design parameters. Likewise, I doubt if they will provide you with a derating factor for using 60 Hz breakers in a 50 Hz application. There is just too much liability involved.

An expensive option is to use a shore power conditioner that will take a wide range of input (in both voltage and frequency) and output what you need for your vessel.

The last one I installed was about $15k and handled 12kw. Here is a link: Shore Power Converters AC12 ||

[Extemporaneous]

Originally Posted by CharlieJ

Extemp-I doubt if you will find any circuit breaker manufacture who will back his products if you use them outside of the design parameters. Likewise, I doubt if they will provide you with a derating factor for using 60 Hz breakers in a 50 Hz application. There is just too much liability involved.

I'm very sure that "they" won't, but it would still be good to know what real life effect the 50 Hz has on 60 Hz breakers and RCDB'S as compared to the CYA statements. After all, North American Breakers (60 Hz) are all over Europe right now. I wonder if those boat owners know how their system is going to react in a trip situation.
In my case I have an Isolation transformer that could take 230 V European and convert it to 120 V, however it won't change the 50 Hz to 60 Hz.

What I want to do is install an RCDB before my transformer and one after my transformer.
I guess at this point I will install the 60 Hz one's (seams like no choice), but it would sure nice to know what affect 50 Hz will have on it?

Can you enlighten me?

Originally Posted by CharlieJ

An expensive option is to use a shore power conditioner that will take a wide range of input (in both voltage and frequency) and output what you need for your vessel.
The last one I installed was about $15k and handled 12kw. Here is a link: Shore Power Converters AC12 ||

I can tell you, that's not going to happen.

Thanks,
Extemp.

[GordMay]

Originally Posted by Extemporaneous

Do you know if there is a predictable relationship when using a 60 Hz breaker and/or RCD Breaker with a 50 Hz supply and that it would just act out of spec, but consistently and predictably, but safely?...

I’m afraid I cannot satisfactorily answer that question.

Faraday’s law would predict the effects of frequency on magnetic characteristics, but I'm certain that there will also be other issues.
Unfortunately, I don’t even know what I don’t know about these other factors.

Many molded case circuit breakers do operate satisfactorily on either 50 or 60Hz.

[Extemporaneous]

Originally Posted by Extemporaneous

In my case I have an Isolation transformer that could take 230 V European and convert it to 120 V, however it won't change the 50 Hz to 60 Hz.

What I want to do is install an RCDB before my transformer and one after my transformer.
I guess at this point I will install the 60 Hz one's (seams like no choice), but it would sure nice to know what affect 50 Hz will have on it?

Okay, since I have not recieved any better guidance here or anywhere else that search engines have taken me on the WWW, I'll be going with North American (60 Hz) RCDB's.
Thinking about it more as to the placement of these, I'm wondering if I need 3 of them??

1. Where my shore power comes in, before my Isolation Transformer.
2. After my Isolation Transformer (for loads not going through the Inverter).
3. And one after my Inverter (For the 120 Volt that the Inverter is producing from the Batteries).

Is this getting silly or do I indeed need 3 of them?
Perhaps I can get away with 2 (I sure hope) if I take everything through the inverter. Don't know if this will cause undue wear on my system as I really don't need and didn't want all my 120 V with that UPS type supply.

If I want proper whole boat protection (GFI) are there any other options and/or do any of you have any comments or suggestions?

Please let me know.

Thanks,
Extemp.