On 14/07/2017 08:46, wrote:
On Thu, 13 Jul 2017 19:10:54 -0600, bud-- wrote:




3 phase. It is not unusual on large services out there in 220v land


(Nice call on RCD.)

------------------------
One of the important questions about an electric power system is how it
handles a hot-to-ground short - a ground fault.

In the US the fault current is carried on the ground system to the
service where it goes across the required neutral-ground bond to the
service neutral and back to the supply transformer. This is an all-metal
path that can supply the high current to trip a breaker. An earth
connection is not allowed to be used because it can not reliably carry a
high current. (What is the current if you connect 120V to a ground rod
that is a code-compliant 25 ohms-to-earth?)

In parts of the UK the neutral is earthed at the supply transformer but
not elsewhere. There is no N-G bond at the building. That means the
fault current return is through the earth, which will not reliably trip
a breaker. I think that is why RCD main-breakers are used - the earth
fault return current will trip an RCD. That may be why this system has
RCDs. The only number I have seen for an RCD trip is 30 mA. That seems
like it would be subject to nuisance trips. It is also the number I have
seen for RCDs protecting people - seems too close to the can't-let-go
current.

In the US, as most of us know, GFCIs to protect people trip at 5 mA.
There are GFIs to protect equipment that trip at 30 mA. And AFCIs
include a ground fault trip, I think always at 50 mA.

-------------------------------
The pictures show devices in series. Likely the top unit is an ordinary
over-current breaker and the bottom one is only an RCD.

Likely a large main breaker in the center (that is how it is marked),
fed from the bottom, feeding 2 - RCD-protected feeders.

------------------------------
A 63 A (67?) 220V 3 ph feed is equivalent to about a 190 A split-phase
service here.

------------------------------
Would be a good idea for the OP to google the breaker information to
find specs and instructions.

-----------------------------
As a warning - the service may only be about 150 A. But a short on the
service wires before the breaker can have a current of thousands of amps
- would be very unpleasant.

------------------------------
And this newsgroup is mostly US, though we humor some foreigners from
north of the border. Happy to answer questions, but would have helped
for the OP to say he is in Thailand, especially on a question like this.

I poked around on the Legrand catalog and found his switch gear. It is
63 amps, the top one is a 3 pole breaker, the bottom one is an RCCB
(RCD in Europe) That particular one is 100MA so it is not protection
for personal in any sense. You are dead by the time that sucker trips.
It is exactly what you say. It just detects a serious ground fault and
trips the main.

http://www.legrand.com.au/products/e...ion/tx3-rccbs/

If you poke around a little you will see all of that stuff in the
picture. That is an Australian site so Thailand is probably in their
marketing area.

Yes. It does say 100 mA on the breaker.

On 13/07/2017 23:27, wrote:
On Thu, 13 Jul 2017 11:28:13 +0630, Lenny Jacobs
wrote:

On 13/07/2017 09:33, wrote:
On Thu, 13 Jul 2017 07:04:53 +0630, Lenny Jacobs
wrote:

On 13/07/2017 03:57, wrote:
On Wed, 12 Jul 2017 10:23:24 +0630, Lenny Jacobs
wrote:

On 12/07/2017 08:54, wrote:

My "suspicion" is any one , or possibly combination of 2, would cause
the problem. Still don't know exactly what amperage the branch
breakers are, but he has a 63 amp "sub-main" that trips. If he has 7.5
amp breakers (equivalent to 15 amp 120 volt) and he has 25 running an
average of 1/4 capacity, that is 46.875 amps. Say the other 4 are at 6
amps each, the main may trip,(70 amps) while shutting any 1 off may
keep it from tripping at 64. The "short" resistance in the 4 may not
be exactly the same - one may draw heavier than the other on a given
day (it IS a "random" fault) - so shutting all 4 off, then turning the
others on, it may be different combinations that work from day to day.

Well, I have about 10 lights, one water heater (about 30 gallon), one
ceiling fan, three refrigerators. When I turned on TV/DVD, used a
kettle, turned on A/C, used the range in the kitchen, the breaker was
not tripped. It would take a lot more than these to overload a 63A breaker.
You have NO IDEA what amperage the other 4 (that cause the trip) are
drawing. What is the rating of the branch circuit breakers? The water
heater is likely 30 amps, the range is likely 40 amps (if it's all
turned on). That is already more than 63 amps!!! If the range is off,
it draws nothing, of course - but you do not indicate if it is in use.
The fridges could be drawing 3.5 amps each - perhaps 7 when starting,
and about the same when running the auto defrost cycle. When it kicked
the kettle wa not in use? Or the AC? Were the lights on? With
everything else turned off, can you turn on the 4 "bad" breakers
without tripping the main?

Can't tell the rating of most of the breakers. The electrician who
installed them did a great job labeling every one of them. The label
sticker is right on the rating. Judging from the size of the breakers,
they could be 13, 16, or 20 A.


In a euro 240 style system I highly doubt most are over 7.5 amps.
My point of mentioning A/C, range, etc. was that besides those
constantly on appliances, the breaker was not tripped when A/C or range
was turned on. The breaker was tripped when A/C or range was not on. So,
it kind of excludes overloading.

Now it turns out that the tripped sub-main breaker is a GFCI, a wet
circuit is almost certain the cause of the problem.

\Being the sub-mains which are being tripped are GFCI breakers, you
can bet the farm on it. No idea why they have such a ludicrous system
- the branch circuits should be GFCI protected.

I just checked eBay. The price is still around $50 a piece.

Maybe I should replace those four problematic breakers with GFCI, beside
replacing the sub-main breaker.
I'd try just replacing the breakers on the problem circuits first -
they should trip at something like 5ma where the mains trip at 30ma?
fault current.

There are so many wires in the sub panel. How do I find the neutral for
the particular breakers? The breaker boxes in the US have bus to which
all the neutral and ground wires connect to. Not this box. So, where are
the neutral wires? And I heard that three phase circuit shares neutral
wire. That makes things more complex.

Even for the breaker boxes in the US, how to find out which neutral wire
goes with which breaker?

On Friday, July 14, 2017 at 9:50:56 PM UTC-4, Lenny Jacobs wrote:
On 13/07/2017 23:27, wrote:
On Thu, 13 Jul 2017 11:28:13 +0630, Lenny Jacobs
wrote:

On 13/07/2017 09:33, wrote:
On Thu, 13 Jul 2017 07:04:53 +0630, Lenny Jacobs
wrote:

On 13/07/2017 03:57, wrote:
On Wed, 12 Jul 2017 10:23:24 +0630, Lenny Jacobs
wrote:

On 12/07/2017 08:54, wrote:

My "suspicion" is any one , or possibly combination of 2, would cause
the problem. Still don't know exactly what amperage the branch
breakers are, but he has a 63 amp "sub-main" that trips. If he has 7.5
amp breakers (equivalent to 15 amp 120 volt) and he has 25 running an
average of 1/4 capacity, that is 46.875 amps. Say the other 4 are at 6
amps each, the main may trip,(70 amps) while shutting any 1 off may
keep it from tripping at 64. The "short" resistance in the 4 may not
be exactly the same - one may draw heavier than the other on a given
day (it IS a "random" fault) - so shutting all 4 off, then turning the
others on, it may be different combinations that work from day to day.

Well, I have about 10 lights, one water heater (about 30 gallon), one
ceiling fan, three refrigerators. When I turned on TV/DVD, used a
kettle, turned on A/C, used the range in the kitchen, the breaker was
not tripped. It would take a lot more than these to overload a 63A breaker.
You have NO IDEA what amperage the other 4 (that cause the trip) are
drawing. What is the rating of the branch circuit breakers? The water
heater is likely 30 amps, the range is likely 40 amps (if it's all
turned on). That is already more than 63 amps!!! If the range is off,
it draws nothing, of course - but you do not indicate if it is in use.
The fridges could be drawing 3.5 amps each - perhaps 7 when starting,
and about the same when running the auto defrost cycle. When it kicked
the kettle wa not in use? Or the AC? Were the lights on? With
everything else turned off, can you turn on the 4 "bad" breakers
without tripping the main?

Can't tell the rating of most of the breakers. The electrician who
installed them did a great job labeling every one of them. The label
sticker is right on the rating. Judging from the size of the breakers,
they could be 13, 16, or 20 A.


In a euro 240 style system I highly doubt most are over 7.5 amps.
My point of mentioning A/C, range, etc. was that besides those
constantly on appliances, the breaker was not tripped when A/C or range
was turned on. The breaker was tripped when A/C or range was not on. So,
it kind of excludes overloading.

Now it turns out that the tripped sub-main breaker is a GFCI, a wet
circuit is almost certain the cause of the problem.

\Being the sub-mains which are being tripped are GFCI breakers, you
can bet the farm on it. No idea why they have such a ludicrous system
- the branch circuits should be GFCI protected.

I just checked eBay. The price is still around $50 a piece.

Maybe I should replace those four problematic breakers with GFCI, beside
replacing the sub-main breaker.
I'd try just replacing the breakers on the problem circuits first -
they should trip at something like 5ma where the mains trip at 30ma?
fault current.

There are so many wires in the sub panel. How do I find the neutral for
the particular breakers? The breaker boxes in the US have bus to which
all the neutral and ground wires connect to. Not this box. So, where are
the neutral wires? And I heard that three phase circuit shares neutral
wire. That makes things more complex.

Even for the breaker boxes in the US, how to find out which neutral wire
goes with which breaker?

You follow the hot wire from the breaker back to the incoming cable
and find the white neutral wire that's with it, that's how you
figure it out in the US. In your case, that
RCD breaker has 4 wires going through it, with one labeled "N"
doesn't it? I don't have the spec sheet for the breaker, but it
seems pretty obvious to me that would be the neutral.

But does any of this really matter? It sounds like you have a serious
safety problem, one that could be lethal, the fault you have must
exceed 100ma, isn't it time to hire an electrician and get it fixed?

On 15/07/2017 08:39, trader_4 wrote:
On Friday, July 14, 2017 at 9:50:56 PM UTC-4, Lenny Jacobs wrote:
On 13/07/2017 23:27, wrote:
On Thu, 13 Jul 2017 11:28:13 +0630, Lenny Jacobs
wrote:

On 13/07/2017 09:33, wrote:
On Thu, 13 Jul 2017 07:04:53 +0630, Lenny Jacobs
wrote:

On 13/07/2017 03:57, wrote:
On Wed, 12 Jul 2017 10:23:24 +0630, Lenny Jacobs
wrote:

On 12/07/2017 08:54, wrote:

My "suspicion" is any one , or possibly combination of 2, would cause
the problem. Still don't know exactly what amperage the branch
breakers are, but he has a 63 amp "sub-main" that trips. If he has 7.5
amp breakers (equivalent to 15 amp 120 volt) and he has 25 running an
average of 1/4 capacity, that is 46.875 amps. Say the other 4 are at 6
amps each, the main may trip,(70 amps) while shutting any 1 off may
keep it from tripping at 64. The "short" resistance in the 4 may not
be exactly the same - one may draw heavier than the other on a given
day (it IS a "random" fault) - so shutting all 4 off, then turning the
others on, it may be different combinations that work from day to day.

Well, I have about 10 lights, one water heater (about 30 gallon), one
ceiling fan, three refrigerators. When I turned on TV/DVD, used a
kettle, turned on A/C, used the range in the kitchen, the breaker was
not tripped. It would take a lot more than these to overload a 63A breaker.
You have NO IDEA what amperage the other 4 (that cause the trip) are
drawing. What is the rating of the branch circuit breakers? The water
heater is likely 30 amps, the range is likely 40 amps (if it's all
turned on). That is already more than 63 amps!!! If the range is off,
it draws nothing, of course - but you do not indicate if it is in use.
The fridges could be drawing 3.5 amps each - perhaps 7 when starting,
and about the same when running the auto defrost cycle. When it kicked
the kettle wa not in use? Or the AC? Were the lights on? With
everything else turned off, can you turn on the 4 "bad" breakers
without tripping the main?

Can't tell the rating of most of the breakers. The electrician who
installed them did a great job labeling every one of them. The label
sticker is right on the rating. Judging from the size of the breakers,
they could be 13, 16, or 20 A.


In a euro 240 style system I highly doubt most are over 7.5 amps.
My point of mentioning A/C, range, etc. was that besides those
constantly on appliances, the breaker was not tripped when A/C or range
was turned on. The breaker was tripped when A/C or range was not on. So,
it kind of excludes overloading.

Now it turns out that the tripped sub-main breaker is a GFCI, a wet
circuit is almost certain the cause of the problem.

\Being the sub-mains which are being tripped are GFCI breakers, you
can bet the farm on it. No idea why they have such a ludicrous system
- the branch circuits should be GFCI protected.

I just checked eBay. The price is still around $50 a piece.

Maybe I should replace those four problematic breakers with GFCI, beside
replacing the sub-main breaker.
I'd try just replacing the breakers on the problem circuits first -
they should trip at something like 5ma where the mains trip at 30ma?
fault current.

There are so many wires in the sub panel. How do I find the neutral for
the particular breakers? The breaker boxes in the US have bus to which
all the neutral and ground wires connect to. Not this box. So, where are
the neutral wires? And I heard that three phase circuit shares neutral
wire. That makes things more complex.

Even for the breaker boxes in the US, how to find out which neutral wire
goes with which breaker?

You follow the hot wire from the breaker back to the incoming cable
and find the white neutral wire that's with it, that's how you
figure it out in the US. In your case, that
RCD breaker has 4 wires going through it, with one labeled "N"
doesn't it? I don't have the spec sheet for the breaker, but it
seems pretty obvious to me that would be the neutral.

But does any of this really matter? It sounds like you have a serious
safety problem, one that could be lethal, the fault you have must
exceed 100ma, isn't it time to hire an electrician and get it fixed?

As I have said earlier, I did ask an electrician about the tripping. He
just shrugged and said it's due to moisture. No need to fix it. Indeed,
during dry season, there is no problem even when all the four
problematic breaker are flipped up.

On Sat, 15 Jul 2017 08:20:53 +0630, Lenny Jacobs
wrote:

On 13/07/2017 23:27, wrote:
On Thu, 13 Jul 2017 11:28:13 +0630, Lenny Jacobs
wrote:

On 13/07/2017 09:33, wrote:
On Thu, 13 Jul 2017 07:04:53 +0630, Lenny Jacobs
wrote:

On 13/07/2017 03:57, wrote:
On Wed, 12 Jul 2017 10:23:24 +0630, Lenny Jacobs
wrote:

On 12/07/2017 08:54, wrote:

My "suspicion" is any one , or possibly combination of 2, would cause
the problem. Still don't know exactly what amperage the branch
breakers are, but he has a 63 amp "sub-main" that trips. If he has 7.5
amp breakers (equivalent to 15 amp 120 volt) and he has 25 running an
average of 1/4 capacity, that is 46.875 amps. Say the other 4 are at 6
amps each, the main may trip,(70 amps) while shutting any 1 off may
keep it from tripping at 64. The "short" resistance in the 4 may not
be exactly the same - one may draw heavier than the other on a given
day (it IS a "random" fault) - so shutting all 4 off, then turning the
others on, it may be different combinations that work from day to day.

Well, I have about 10 lights, one water heater (about 30 gallon), one
ceiling fan, three refrigerators. When I turned on TV/DVD, used a
kettle, turned on A/C, used the range in the kitchen, the breaker was
not tripped. It would take a lot more than these to overload a 63A breaker.
You have NO IDEA what amperage the other 4 (that cause the trip) are
drawing. What is the rating of the branch circuit breakers? The water
heater is likely 30 amps, the range is likely 40 amps (if it's all
turned on). That is already more than 63 amps!!! If the range is off,
it draws nothing, of course - but you do not indicate if it is in use.
The fridges could be drawing 3.5 amps each - perhaps 7 when starting,
and about the same when running the auto defrost cycle. When it kicked
the kettle wa not in use? Or the AC? Were the lights on? With
everything else turned off, can you turn on the 4 "bad" breakers
without tripping the main?

Can't tell the rating of most of the breakers. The electrician who
installed them did a great job labeling every one of them. The label
sticker is right on the rating. Judging from the size of the breakers,
they could be 13, 16, or 20 A.


In a euro 240 style system I highly doubt most are over 7.5 amps.
My point of mentioning A/C, range, etc. was that besides those
constantly on appliances, the breaker was not tripped when A/C or range
was turned on. The breaker was tripped when A/C or range was not on. So,
it kind of excludes overloading.

Now it turns out that the tripped sub-main breaker is a GFCI, a wet
circuit is almost certain the cause of the problem.

\Being the sub-mains which are being tripped are GFCI breakers, you
can bet the farm on it. No idea why they have such a ludicrous system
- the branch circuits should be GFCI protected.

I just checked eBay. The price is still around $50 a piece.

Maybe I should replace those four problematic breakers with GFCI, beside
replacing the sub-main breaker.
I'd try just replacing the breakers on the problem circuits first -
they should trip at something like 5ma where the mains trip at 30ma?
fault current.

There are so many wires in the sub panel. How do I find the neutral for
the particular breakers? The breaker boxes in the US have bus to which
all the neutral and ground wires connect to. Not this box. So, where are
the neutral wires? And I heard that three phase circuit shares neutral
wire. That makes things more complex.

Even for the breaker boxes in the US, how to find out which neutral wire
goes with which breaker?


Neutrals are not really tied to a breaker except for that RCCB and
that is all of the neutrals on that feeder. You do need to keep track
of the neutral for each outgoing cable but it is only important when
you are disconnecting it and you want to keep the ungrounded
conductors grouped so you can assure they are on different phases.

On Sat, 15 Jul 2017 08:47:11 +0630, Lenny Jacobs
wrote:


As I have said earlier, I did ask an electrician about the tripping. He
just shrugged and said it's due to moisture. No need to fix it. Indeed,
during dry season, there is no problem even when all the four
problematic breaker are flipped up.

With that much fault current this is probably more than a little
moisture. I bet you have boxes filling up with water. I would start
with a visual inspection of all of your outdoor fixtures and junction
boxes. You might also have some splices underground that are not
waterproof. Without actually looking at your installation it is hard
to guess from half way around the planet. ;-)

On 15/07/2017 09:03, wrote:
On Sat, 15 Jul 2017 08:47:11 +0630, Lenny Jacobs
wrote:


As I have said earlier, I did ask an electrician about the tripping. He
just shrugged and said it's due to moisture. No need to fix it. Indeed,
during dry season, there is no problem even when all the four
problematic breaker are flipped up.

With that much fault current this is probably more than a little
moisture. I bet you have boxes filling up with water. I would start
with a visual inspection of all of your outdoor fixtures and junction
boxes. You might also have some splices underground that are not
waterproof. Without actually looking at your installation it is hard
to guess from half way around the planet. ;-)

I suspect it'd take more than just visual inspection. I see some
above-ground junction boxes. Not sure if there are underground junction
boxes. I do have an underground junction box for phone line. How to keep
water from getting into underground junction boxes? I have no clue.

On 15/07/2017 08:55, wrote:
On Sat, 15 Jul 2017 08:20:53 +0630, Lenny Jacobs
wrote:

On 13/07/2017 23:27, wrote:
On Thu, 13 Jul 2017 11:28:13 +0630, Lenny Jacobs
wrote:

On 13/07/2017 09:33, wrote:
On Thu, 13 Jul 2017 07:04:53 +0630, Lenny Jacobs
wrote:

On 13/07/2017 03:57, wrote:
On Wed, 12 Jul 2017 10:23:24 +0630, Lenny Jacobs
wrote:

On 12/07/2017 08:54, wrote:

My "suspicion" is any one , or possibly combination of 2, would cause
the problem. Still don't know exactly what amperage the branch
breakers are, but he has a 63 amp "sub-main" that trips. If he has 7.5
amp breakers (equivalent to 15 amp 120 volt) and he has 25 running an
average of 1/4 capacity, that is 46.875 amps. Say the other 4 are at 6
amps each, the main may trip,(70 amps) while shutting any 1 off may
keep it from tripping at 64. The "short" resistance in the 4 may not
be exactly the same - one may draw heavier than the other on a given
day (it IS a "random" fault) - so shutting all 4 off, then turning the
others on, it may be different combinations that work from day to day.

Well, I have about 10 lights, one water heater (about 30 gallon), one
ceiling fan, three refrigerators. When I turned on TV/DVD, used a
kettle, turned on A/C, used the range in the kitchen, the breaker was
not tripped. It would take a lot more than these to overload a 63A breaker.
You have NO IDEA what amperage the other 4 (that cause the trip) are
drawing. What is the rating of the branch circuit breakers? The water
heater is likely 30 amps, the range is likely 40 amps (if it's all
turned on). That is already more than 63 amps!!! If the range is off,
it draws nothing, of course - but you do not indicate if it is in use.
The fridges could be drawing 3.5 amps each - perhaps 7 when starting,
and about the same when running the auto defrost cycle. When it kicked
the kettle wa not in use? Or the AC? Were the lights on? With
everything else turned off, can you turn on the 4 "bad" breakers
without tripping the main?

Can't tell the rating of most of the breakers. The electrician who
installed them did a great job labeling every one of them. The label
sticker is right on the rating. Judging from the size of the breakers,
they could be 13, 16, or 20 A.


In a euro 240 style system I highly doubt most are over 7.5 amps.
My point of mentioning A/C, range, etc. was that besides those
constantly on appliances, the breaker was not tripped when A/C or range
was turned on. The breaker was tripped when A/C or range was not on. So,
it kind of excludes overloading.

Now it turns out that the tripped sub-main breaker is a GFCI, a wet
circuit is almost certain the cause of the problem.

\Being the sub-mains which are being tripped are GFCI breakers, you
can bet the farm on it. No idea why they have such a ludicrous system
- the branch circuits should be GFCI protected.

I just checked eBay. The price is still around $50 a piece.

Maybe I should replace those four problematic breakers with GFCI, beside
replacing the sub-main breaker.
I'd try just replacing the breakers on the problem circuits first -
they should trip at something like 5ma where the mains trip at 30ma?
fault current.

There are so many wires in the sub panel. How do I find the neutral for
the particular breakers? The breaker boxes in the US have bus to which
all the neutral and ground wires connect to. Not this box. So, where are
the neutral wires? And I heard that three phase circuit shares neutral
wire. That makes things more complex.

Even for the breaker boxes in the US, how to find out which neutral wire
goes with which breaker?


Neutrals are not really tied to a breaker except for that RCCB and
that is all of the neutrals on that feeder. You do need to keep track
of the neutral for each outgoing cable but it is only important when
you are disconnecting it and you want to keep the ungrounded
conductors grouped so you can assure they are on different phases.

In the US, one can buy cables that have hot, neutral, and ground wires
all in a sheath. It's very easy to tell which hot goes with which
neutral. Here, people use separate wires. They maybe black, red, green,
blue, etc. How to figure out which two wires go with which breaker?
Impossible, I think.

On Sat, 15 Jul 2017 11:57:51 +0630, Lenny Jacobs
wrote:

On 15/07/2017 09:03, wrote:
On Sat, 15 Jul 2017 08:47:11 +0630, Lenny Jacobs
wrote:


As I have said earlier, I did ask an electrician about the tripping. He
just shrugged and said it's due to moisture. No need to fix it. Indeed,
during dry season, there is no problem even when all the four
problematic breaker are flipped up.

With that much fault current this is probably more than a little
moisture. I bet you have boxes filling up with water. I would start
with a visual inspection of all of your outdoor fixtures and junction
boxes. You might also have some splices underground that are not
waterproof. Without actually looking at your installation it is hard
to guess from half way around the planet. ;-)

I suspect it'd take more than just visual inspection. I see some
above-ground junction boxes. Not sure if there are underground junction
boxes. I do have an underground junction box for phone line. How to keep
water from getting into underground junction boxes? I have no clue.

You don't really keep the water out, you just use waterproof splices.
They are typically a crimp splice in a silicone filled tube. Above
ground you just be sure they are arranged to drain and that the
conductors are not near the bottom of the box or touching the sides.

On Sat, 15 Jul 2017 01:33:44 -0400, wrote:

On Sat, 15 Jul 2017 11:57:51 +0630, Lenny Jacobs
wrote:

On 15/07/2017 09:03, wrote:
On Sat, 15 Jul 2017 08:47:11 +0630, Lenny Jacobs
wrote:


As I have said earlier, I did ask an electrician about the tripping. He
just shrugged and said it's due to moisture. No need to fix it. Indeed,
during dry season, there is no problem even when all the four
problematic breaker are flipped up.

With that much fault current this is probably more than a little
moisture. I bet you have boxes filling up with water. I would start
with a visual inspection of all of your outdoor fixtures and junction
boxes. You might also have some splices underground that are not
waterproof. Without actually looking at your installation it is hard
to guess from half way around the planet. ;-)

I suspect it'd take more than just visual inspection. I see some
above-ground junction boxes. Not sure if there are underground junction
boxes. I do have an underground junction box for phone line. How to keep
water from getting into underground junction boxes? I have no clue.

You don't really keep the water out, you just use waterproof splices.
They are typically a crimp splice in a silicone filled tube. Above
ground you just be sure they are arranged to drain and that the
conductors are not near the bottom of the box or touching the sides.
Perhaps plant "umbrella plants" over the jboxes?????