Circuit Breaker for Mains Supply

[Cashboy]

I understand that to comply with the Government Electric regulations one has to have a 50 Amp circuit breaker on a 15 (45) supply/meter.

 

I have a 16mm copper cable running from the meter to the house/office (20 meters) to a 125 Amp 2 pole mains switch.

I understand that 16mm copper is good to carry a load up to 92 Amp and use an MCB of 80 Amp.

 

Consumer units (3 off) have Main Switches of 100 Amp and two 80 Amp RCDs in each consumer unit  (UK consumer units)

 

 

 

I intend to run the following items in my house/office:

3 no. 4,500 watt showers

4 no. air conditioning units

1  no. water heater 6,500 watt

1  no. water pump

1  no. 2,300 watt oven

1  no. 4,500 watt commercial expresso coffee machine

2  no. 3,000 watt UK electric kettles.

 

Obviously not everything will be on at the same time.

 

I realise for the inspection, there has to be a 2 pole 50 Amp MCB

 

 

 

Questions:   

(1)  Is the government mains circuit breaker supposed to be a C Type or D Type?

(2) The connections from the mains supply; should it be connect into the bottom of the MCB or does it not make any difference?

 

I am thinking that after the inspection, I could change the Mains MCB to a 2 point 63 Amp.

 

I understand that the difference between a C type and D type is:

Type C - trips between 5 and 10 times full load current

Type D - trips between 10 and 20 times full load current

 

I gather that on that basis a Type D would take longer to trip than a Type C on a heavy load?

 

My question is:

Would it be safe to put a 2 Point 63 Amp Type D on the incoming mains?

 

 

 

 

 

 

 

 

 

 

 

 

[bankruatsteve]

Your main breaker at 63 amp should be OK for your purpose and PEA inspection.

Most breakers available in Thailand are C curve.  Just go with that.

2 hours ago, Cashboy said:

two 80 Amp RCDs

??  Do you have photo of that?

[Crossy]

That first breaker will do the trick, just replace the main switch in your primary CU.

Most MCBs here are "C" curve.

With an MCB it matters not which way round it goes.

 

CU's look good.

 

IMPORTANT NOTE - inorder to pass the inspection you MUST wire the incoming supply as MEN as shown in this diagram. Yes, the incoming neutral does go to the ground bar first. once you have the permanent meter you can do what you like.

 

 

 

 

[Crossy]

2 minutes ago, bankruatsteve said:

Your main breaker at 63 amp should be OK for your purpose and PEA inspection.

 

We "failed" our initial inspection with a 63A, that said the man never returned to verify that I changed it (I did, but the 63A is back in now).

 

Zoom in on his photo to see the 80A x 30mA RCDs

[bankruatsteve]

8 minutes ago, Crossy said:

 

We "failed" our initial inspection with a 63A, that said the man never returned to verify that I changed it (I did, but the 63A is back in now).

Oh OK.  I thought I read a while back that PEA OK with 63amp now.  Guess not.
Nobody in my area gets inspected anyway.  ????

[Crossy]

9 minutes ago, bankruatsteve said:

Oh OK.  I thought I read a while back that PEA OK with 63amp now.  Guess not.
Nobody in my area gets inspected anyway.  ????

 

As with most things here it varies from area to area.

 

Our "inspection" consisted of the man looking at the CU, mentioning the breaker, looking at the top of the rod and spending the rest of the 30 minute time slot gassing with Madam.

 

[Sophon]

On 10/7/2020 at 4:13 PM, Crossy said:

 

We "failed" our initial inspection with a 63A, that said the man never returned to verify that I changed it (I did, but the 63A is back in now).

 

Zoom in on his photo to see the 80A x 30mA RCDs

We went to the local PEA office to ask if they wanted 50A or 63A main breaker, and the "boss man" told us to just go with the 63A. The "inspection" was a 5 minute talk outside our gate about changing to a permanent supply, no checks or anything.