Question On Electrical Works

[Gymrat76 0]

I just checked my new block's postcode and it says:

"Your block has not been provided with higher electrical loading. You will need to apply for an HDB permit to install new 15 Amps power points for air-conditioners or other higher capacity equipment/appliances (e.g. high powered IT equipment).

Under the Building Control (Amendment) Act, flat owners are required to engage Building & Construction Authority-trained air-con installers to install the air-con outside their flats and to keep the authority informed when they carry out the installation works.

However, for installation of air-conditioners using existing approved air-con points and other electrical works, there is no need to apply for an HDB permit. You need to submit an application (using SP Services Ltd's Form CS/5H) to HDB. Thereafter you may apply to SP Services Ltd to test the extensions."

Its a 4 room flat, and the 3 bedrooms already have aircond installed (split units). We intend to knock the wall down to enlarge the common room (this will mean 2 existing aircon for master). However, we also want to install an aircond for the living room, which currently does not have aircond.

Can I shift the FCUs around such that:

1. 2 FCU in living room (perhaps 2x9000BTU)

2. 1 higher capacity for master bedroom (1x14000BTU)

3. 1 FCU in remaining common room (untouched)

Would I need to apply for permit or any other kind of upgrade when I do my reno to accommodate the additional aircond? Thanks

[beluga 1]

It just means your current house cannot install 2 compressors. Biggest compressor sold in the market is 28800 BTU? You split this BTU among the rooms lor. Total combined BTU can still be more than the 28800 but it will mean you should not turn on all at the same time.

Edited March 23, 2012 by beluga

[Gymrat76 0]

It just means your current house cannot install 2 compressors. Biggest compressor sold in the market is 28800 BTU? You split this BTU among the rooms lor. Total combined BTU can still be more than the 28800 but it will mean you should not turn on all at the same time.

Any way for me to upgrade electrical capacity during my house reno to increase capacity?

[beluga 1]

Don't think so... If can why would hdb bother to provide such info?

[Gymrat76 0]

Don't think so... If can why would hdb bother to provide such info?

It says:

Electrical Work that requires permit

Flats that have not been provided with higher electrical loading, require an HDB permit to install new 15 Amps power points for air-conditioners or other higher capacity equipment/appliances.

I took this to mean we can, then again, I know nuts about electrical work haha

[May_dream1 14]

It says:

Electrical Work that requires permit

Flats that have not been provided with higher electrical loading, require an HDB permit to install new 15 Amps power points for air-conditioners or other higher capacity equipment/appliances.

I took this to mean we can, then again, I know nuts about electrical work haha

It means you cannot install aircon without applying to hdb. But if your resale flat already have the point for aircon then no need to apply.

Electrical loading is done centrally. The higher capacity have to be upgraded by hdb for whole block. If your block have never been upgraded, nothing you can do about it. You mix the application for aircon point to application for higher loading.

[beluga 1]

It says:

Electrical Work that requires permit

Flats that have not been provided with higher electrical loading, require an HDB permit to install new 15 Amps power points for air-conditioners or other higher capacity equipment/appliances.

I took this to mean we can, then again, I know nuts about electrical work haha

I know nuts about this too but I can tell you from experience.

My new place had a System 3 but the study room did not have an aircon. As I wanted to convert it into a room for my daughter, I sought out a few option

1) Can add another fan coil to the System 3?

Answer I got: You may but you can't turn on all at the same time which defeats the purpose.

2) Add another compressor, which in this case, I can add another Sys 3 to cover the study room and living room.

Answer I got: From both the ID and Aircon contractor, "Is your unit been upgraded? If so then can add 2 compressor".

3) Teardown the existing Sys3 and upgrade to Sys4, forgo living room.

I chose option 3 finally for cost reason and sold away the existing sys3.

[Gymrat76 0]

I know nuts about this too but I can tell you from experience.

My new place had a System 3 but the study room did not have an aircon. As I wanted to convert it into a room for my daughter, I sought out a few option

1) Can add another fan coil to the System 3?

Answer I got: You may but you can't turn on all at the same time which defeats the purpose.

2) Add another compressor, which in this case, I can add another Sys 3 to cover the study room and living room.

Answer I got: From both the ID and Aircon contractor, "Is your unit been upgraded? If so then can add 2 compressor".

3) Teardown the existing Sys3 and upgrade to Sys4, forgo living room.

I chose option 3 finally for cost reason and sold away the existing sys3.

Thanks everyone. I did some reading last night and basically found out that older units like mine that have not been upgraded is only allowed one condenser unit (CU), whereas newer blocks or those with upgraded electrical capacity are allowed a max of two CU. I suppose the only option if I want to have aircon for larger masterbedroom, living room and one common room is to get a system 3, but with a larger capacity CU and to get an inverter system. I understand that inverters are more expensive, but its the only way to avoid going over the 8.5A continuous running current should all units be turned on at once?

[May_dream1 14]

Inverter and non inverter not going to make much different, maybe 500? It's better than overloading.

[EoneKhaled 0]

How/where to find out that my block had provided with higher electrical loading or not?

I just checked my new block's postcode and it says:

"Your block has not been provided with higher electrical loading. You will need to apply for an HDB permit to install new 15 Amps power points for air-conditioners or other higher capacity equipment/appliances (e.g. high powered IT equipment).

Under the Building Control (Amendment) Act, flat owners are required to engage Building & Construction Authority-trained air-con installers to install the air-con outside their flats and to keep the authority informed when they carry out the installation works.

However, for installation of air-conditioners using existing approved air-con points and other electrical works, there is no need to apply for an HDB permit. You need to submit an application (using SP Services Ltd's Form CS/5H) to HDB. Thereafter you may apply to SP Services Ltd to test the extensions."

Its a 4 room flat, and the 3 bedrooms already have aircond installed (split units). We intend to knock the wall down to enlarge the common room (this will mean 2 existing aircon for master). However, we also want to install an aircond for the living room, which currently does not have aircond.

Can I shift the FCUs around such that:

1. 2 FCU in living room (perhaps 2x9000BTU)

2. 1 higher capacity for master bedroom (1x14000BTU)

3. 1 FCU in remaining common room (untouched)

Would I need to apply for permit or any other kind of upgrade when I do my reno to accommodate the additional aircond? Thanks

[bepgof 20]

Allow me throw u some light on "power" into hdb residential unit.

- No 3-phase loads allowed.

- Maximum 32A, single phase (Y,Y, B or R, S, T)allowed in a single residential unit.

- All loads MUST go through MCCB(overload detection) and a ELCB (then)(for earth leakage detection), now called RCCB(housed in the incoming DB), so any single load that has earth leakage will trip the whole incoming power.

- 15A 3-pin socket( a bit dangerous to me, undersized) or isolator for system 3.

- 20A Isolator for system 4.

Image if you draw 20A now, you left only 12A for other loads.

It is not a question of 2 "compressors" not allowed, rather is the "total power" issue. You can install 2 x single system (each draw abt 8A, 230V)= 2 compressors, or you can install 3 x single system = total 24A (if 3 running at same time).

"Last time" only maximum 20A MCCB/ELCB in coming DB. Now 32A. MCCB = Moulded Casing Circuit Breaker(for magnetic, thermal overload detection)

The regulation is to prevent an unexpected "overload" situation in the electrical riser cables, in case all households drawing maximum of 32A at the same time(esp at night). In fact, when laying power cables to each households, there must consider the balance distribution of 3-phase power, meaning that you use red phase, you neighbour will use yellow or blue phase. These are already considered in power cable laying SCHEDULE. Without such Schedule, contractor would just "anyhow" tap the phase, therefore could couse one or 2 phases heavily in use while the 3rd phase "underload" - this causes "stresses" to power cables. I think I "talk" too much better stop here before confusion arises.

[EoneKhaled 0]

Thanks bepgof, very use full infor you share there....

Let talk about cable size:

What is the size for 13A sso,

the size of 15A sso for air con,

the size of lighting.

the size of storage water heater,

the size of celing fan.?

[EoneKhaled 0]

Thanks bepgof, very use full infor you share there....

Let talk about cable size: What is the size for 13A sso the size of 15A sso for air con, the size of lighting, the size of storage water heater, the size of celing fan.?

[bepgof 20]

Thanks bepgof, very use full infor you share there....

Let talk about cable size:

What is the size for 13A sso,

the size of 15A sso for air con,

the size of lighting.

the size of storage water heater,

the size of celing fan.?

Actually HDB unit installed no MCCB, only curve "B" MCB = miniature circuit breaker( only has thermal overload trip feature).

There are too many cable types with different isolation(pvc, rubble, oil, paper, alu foil..)For HDB unit application, mainly use PVC which allows maximum 70 degC toralent(cont current flowing through). If "overcurrent", excessive heat will spoil the isolation dielectric feature of the pvc and therefore cause "short circuit".

As rule of thumb, 2.5mmsq= 5A, 4mmsq=8A, 6mmsq=12A, 10mmsq=20A, 16mmsq=32A. The question here is HOW the cable "tapping" is done.

For heater, aircon, or anything with single load type >=15A, should tap the cable directly from the output of RCCB (or throught a 20A single pole mcb, curve "B" type) to the SSO, no multidrop tapping, which is allowed in lighting.

At DB, you can see some 10A, 16A, 20A single poles mcbs. 10A meant for lighting/fan, etc. 16A/20A meant for power SSOs, heater, aircon, etc.

Portable heaters, these days, can go up to 2500watt(need single sso or isolator, 15/20A, min 10mmsq cable). Central storage heater (see what size in term of watt), aircon say system 3, 15A, min 6mmsq. Lighting is "multiple dropping", diveided into zone 1, zone 2, 3 etc, min 4mmsq. Fan with 56 inch blade is abt 120watt, can be treated as "lighting".

Important thing is for the 13A SSOs, make sure not more than 4 ssos (single + multiple gangs) in one single loop(best at least 6mm sq). Mine used 10mmsq, i insisted.

[EoneKhaled 0]

Actually HDB unit installed no MCCB, only curve "B" MCB = miniature circuit breaker( only has thermal overload trip feature).

There are too many cable types with different isolation(pvc, rubble, oil, paper, alu foil..)For HDB unit application, mainly use PVC which allows maximum 70 degC toralent(cont current flowing through). If "overcurrent", excessive heat will spoil the isolation dielectric feature of the pvc and therefore cause "short circuit".

As rule of thumb, 2.5mmsq= 5A, 4mmsq=8A, 6mmsq=12A, 10mmsq=20A, 16mmsq=32A. The question here is HOW the cable "tapping" is done.

For heater, aircon, or anything with single load type >=15A, should tap the cable directly from the output of RCCB (or throught a 20A single pole mcb, curve "B" type) to the SSO, no multidrop tapping, which is allowed in lighting.

At DB, you can see some 10A, 16A, 20A single poles mcbs. 10A meant for lighting/fan, etc. 16A/20A meant for power SSOs, heater, aircon, etc.

Portable heaters, these days, can go up to 2500watt(need single sso or isolator, 15/20A, min 10mmsq cable). Central storage heater (see what size in term of watt), aircon say system 3, 15A, min 6mmsq. Lighting is "multiple dropping", diveided into zone 1, zone 2, 3 etc, min 4mmsq. Fan with 56 inch blade is abt 120watt, can be treated as "lighting".

Important thing is for the 13A SSOs, make sure not more than 4 ssos (single + multiple gangs) in one single loop(best at least 6mm sq). Mine used 10mmsq, i insisted.

What happen if I install 10 13A SSOs in single loop using 16A MCB and 2.5mm wire?