Hedges
I See Electromagnetic Fields!
- Joined
- Mar 28, 2020
- Messages
- 20,059
Lots of us have legacy systems from earlier years without the same version of NEC, to the fireman just has to take his chances/use his judgement.
If he puts a fire ax through a PV panel or steps on it, more likely to be a problem.
Even the walkway to access roof is interpreted differently in different places.
If he walks on the eves which overhang beyond the wall of a 2 story house, might that collapse?
One location incudes that in 3' walkway, another say 3' inside the supporting wall.
Newest code only requires a walkway on the side fireman would climb, the North East side in my case closest to the street. That lets me panel over to the eves on South West side.
Also, 3' wide area straddling the ridge 18" on either side, so he can choose which side to vent (depending on wind direction) rather than 3' clear on both sides like previous revision NEC.
I think the code should have allowed no RSD so long as wires outside the array are run in metal conduit.
There are some model RSD good for 4 panels per unit. Depending on voltage/current limits that might be the most economical.
If I relocate some 120W 12V panels from ground mounts onto roof, I'm thinking 3 in series for 360W 67 Voc, and 4 of those strings into one RSD.
Then I'll only need 2 RSD per 24 panel 2700W string.
If you can do without RSD, so much the better.
Arc-fault is probably a more useful feature to protect your house from having a fire in the first place.
If he puts a fire ax through a PV panel or steps on it, more likely to be a problem.
Even the walkway to access roof is interpreted differently in different places.
If he walks on the eves which overhang beyond the wall of a 2 story house, might that collapse?
One location incudes that in 3' walkway, another say 3' inside the supporting wall.
Newest code only requires a walkway on the side fireman would climb, the North East side in my case closest to the street. That lets me panel over to the eves on South West side.
Also, 3' wide area straddling the ridge 18" on either side, so he can choose which side to vent (depending on wind direction) rather than 3' clear on both sides like previous revision NEC.
I think the code should have allowed no RSD so long as wires outside the array are run in metal conduit.
There are some model RSD good for 4 panels per unit. Depending on voltage/current limits that might be the most economical.
If I relocate some 120W 12V panels from ground mounts onto roof, I'm thinking 3 in series for 360W 67 Voc, and 4 of those strings into one RSD.
Then I'll only need 2 RSD per 24 panel 2700W string.
If you can do without RSD, so much the better.
Arc-fault is probably a more useful feature to protect your house from having a fire in the first place.