Hi All,
Just trying to get my head around the wording in Table C1, load group D, in regards to space heating and working out the MD for the entire installation.
Load group B(i) is for socket outlets not exceeding 10A and permanently connected electrical equipment not exceeding 10A and not included in other load groups.
Load group D is for fixed space heating or aircon equipment or socket outlets rated at more than 10A for the connection therof.
In their first example(C2.3.2) the 1000w heater is just included in Load Group B(i) and calculated as just another point.
My question is,
is the 10A limit for each fixed heater, or the total sum of all the fixed heaters?
eg. 1 x fixed wired 1kw heater falls into load group B(i), what if we have 5 x 1kw heaters around a house? Would that then just be calculated as 5 points in load group B(i) or has it now moved into load group D and we take 75% of the total load of heating?
Max demand Table C1
Re: Max demand Table C1
It's for each point.
- for a single residential unit (column 2); count each item of p.c. equipment as if it were a socket point (10 A for 1st 20 points, 5 A for next 20, etc)
So if you have eg 5 1 kW fixed heaters, that haven't been included in another load group, then it's 5 more points counted in B1.
- for a single residential unit (column 2); count each item of p.c. equipment as if it were a socket point (10 A for 1st 20 points, 5 A for next 20, etc)
So if you have eg 5 1 kW fixed heaters, that haven't been included in another load group, then it's 5 more points counted in B1.
- Rating: 16.67%
Re: Max demand Table C1
Thanks Aleck,
I thought that was how I read it, but it just didn't seem right to me, so started to doubt myself.
I have looked at a few jobs lately where there is over 10kw of fixed space heaters getting installed, yet because each individual heater is less than 10A, they are calculated as just another point, ending up having little more effect on the max demand calculation other than adding another 5 or 6 points to B(i).
I thought that was how I read it, but it just didn't seem right to me, so started to doubt myself.
I have looked at a few jobs lately where there is over 10kw of fixed space heaters getting installed, yet because each individual heater is less than 10A, they are calculated as just another point, ending up having little more effect on the max demand calculation other than adding another 5 or 6 points to B(i).
Re: Max demand Table C1
remember MD can be done by any of the methods listed.
For a single house there's usually little point in doing a calculation; as we can rely on "limitation"
ie whatever the overcurrent protection for the mains is, the applied load can't exceed that value for long enough to cause damage.
Of course, if the actual load is well up; we may need to use higher protection rating and therefore bigger cable; and that's likely to put the customer into a higher price bracket for fixed charges.
For a single house there's usually little point in doing a calculation; as we can rely on "limitation"
ie whatever the overcurrent protection for the mains is, the applied load can't exceed that value for long enough to cause damage.
Of course, if the actual load is well up; we may need to use higher protection rating and therefore bigger cable; and that's likely to put the customer into a higher price bracket for fixed charges.
Re: Max demand Table C1
B(i) includes "Permanently connected electrical equipment not exceeding 10 A and not included in other load groups"
How is the strip heater not included in group D?
And would B(i) also apply to an airconditioner less than 10A?
How is the strip heater not included in group D?
And would B(i) also apply to an airconditioner less than 10A?
Re: Max demand Table C1
Yes, this would also apply for an airconditioning unit < 10A.
see note i.
Example 1 [ C 2.3.2.1] includes a 1000W strip heater as 1 point in load group B(i).
Example 2 [ C2.3.2.2 includes a 4 kw airconditioner in load group D
Accordingly for any fixed appliance: < = 10 A use load group B(i); > 10 A use another load group
see note i.
Example 1 [ C 2.3.2.1] includes a 1000W strip heater as 1 point in load group B(i).
Example 2 [ C2.3.2.2 includes a 4 kw airconditioner in load group D
Accordingly for any fixed appliance: < = 10 A use load group B(i); > 10 A use another load group