For an outdoor seating area of a restaurant heated by 'non-glow' electric radiant panel heaters (in winter) what is a minimum acceptable globe temperature reading in the area?
marko
Hello,
I am trying to write a standard spec. for a fan coil unit fan speed controller. Speed controllers on fan coils are potentiometer operated for balancing air flow. The fans we use are normally two speed(then BMS controlled). FCU's are single phase and 240V mains powered. The fans are up to...
Hello!
Where you have ESR cabling "Earth Sheath Return" on a 3phase wye system, am i correct in saying that you cannot tong test each phase and read the correct current flow?(unless the load is balanced..)
This is because the neutral current is travelling back up the sheath?
To get an accurate...
Hello all!
When you install an earthing electrode for a LV M.E.N distribution system, what sort of backfill should you use around it? Does it depend on the soil makeup to the area?
I am told to use bentonite and i dont know what it is and cannot find much about it. Is there a better material...
Hi list,
Can a human eye distinguish between 350 and 400 lux lighting levels?
I can understand that between 0 and 50 lux, there is a big difference between illumination, but as you go higher in lighting level over an area, will a human eye notice that some areas are at 400 lux and other areas...
Hello,
If you have a setup where there is a 11kv/415V transformer feeding into a main circuit breaker, then on to a switchboard, what is the advantage of having an earth leakage CT on the neutral at the main circuit breaker point. The CT operates the shunt trip of the main circuit breaker.
Is...
Hello,
I understand that with 'low pressure hot water' (hydronic) heating systems fed from water heaters (boilers) it is not good practice to have a mixture of forced draft fan convectors (i.e. heating coil with fan- as per Dunham Bush units) on the same piping circuit as flat panel radiators...
Hi all,
Should a roof space (attic) be ventilated in a commercial single storey building (maximum/minimum design ambient temps of 36 / 4 oC) containinng air conditioning ductwork if both the ceiling and roof areas are well insulated and provided with moisture barriers.
Is it possible that...
Hello,
A cable that requires sheilding for EMC has, if it is a multi-core cable, an earthed sheild around it, and several earth conductors it in, but if your using single core cables, with several in parallel, can you install the single active cores in an earthed steel duct? Assuming the duct...
Hello all!
Are all EMC cables multicore?
Im not entirely sure how an EMC cable works, but can you have several single core cables per phase running from a VSD to a motor that are EM sheilded? Or do you have to use several multi-core cables that are connected in some special formation...
60hzhmmmm, i do not fully understand what you mean. could you please explain a little more? Are you saying that in the area of the motor, there will be 45kW of heat? I am trying to estimate a heat load for a HVAC calc
I agree that a 45 kW motor will turn that 45kW of energy into some mechanical...
Hello.
If I have a 45kW 3-phase electric motor, can I estimate how much heat is generated from it?
For example, if I know that the power factor is 0.78, is it reasonable to assume all the inefficiencies eventually translate to heat? So that I can say about 10kW of heat is generated...
I agree.
How can you then calculate how long a cable will last being overloaded but not at a short circuit fault level.
For example, back to our 100amp rated cable (lets say pvc insulated), can you determin how long it will last for running continuously at say 140amps?
I know of a way to...
Hello,
If you have a cable that is rated to, say 100amps, how long will it last for, running at 100A??
Will it run forever, or is there some sort of degredation as it is run at its limit?
Does a cable have a let through energy rating of sorts that can be calculated from current and time...
Hello!
Does anyone know why high voltage discharge lighting is limited to 15 000V?? Is there a simple practical reason, or is there a saftey issue with higher voltages?
Thankyou,
Marko T
I understand that rubber vibration isolations units are widely used as they offer a high degree of noise and vibration isolation. Is it the case that neoprene units are less effecient?
Hello.
Do cables that sit in water have to be derated?
The situation I am refering too, is where i have a submains cable that is installed underground in heavy duty conduit. The conduit is filled up with water completely and the water is not draining anywhere.
Should the cable current rating...
Hi!
What the advantages and dis-advantages are in either fitting 'rubber' flexible connections to items of vibrating pant (ie pumps) or 'neoprene' (synthetic rubber) flexible connections.
Thank you.
Hello!
Would anyone know if an 11kV/415V substation rated at 3000kVA would have the same heat load as a 415V switchboard also rated at 3000kVA.
Do the 11kV transformers give off the same amount of heat as the 415V switchboard? They are both rated to 3000kVA however, when i stood next to each...
